Veröffentlichungsreihe der Forschungsgruppe Gesundheitsrisiken und Präventionspolitik Wissenschaftszentrum Berlin für Sozialforschung
ISSN-0935-8137
P92-203
Evaluation of work-related intervention studies to prevent chronification of back disorders
von
Gustav Wickström
Berlin, März 1992
Gustav Wickström ist Professor am Regional Institute of Occupational Health in Turku, Finnland.
Publications series of the research group
"Health Risks and Preventive Policy"
Wissenschaftszentrum Berlin für Sozialforschung D—1000 Berlin 30, Reichpietschufer 50
Tel.: 030/25491-577
Abstract
Da die Berufstätigkeit einen wesentlichen Einfluß auf Entste
hung und Verlauf von Rückenschmerz hat, ist die Modifikation von Einflußfaktoren am Arbeitsplatz ein wichtiger Ansatz zur Prävention des Rückenschmerzes. Die Studie trägt den epidemio
logischen Wissensstand zusammen und gibt einen Überblick über seit den 80er Jahren in verschiedenen Ländern durchgeführte ar beitsplatzbezogene InterventionsStudien. Es wird zwischen Pri
mär- , Sekundär- und Tertiärformen der Prävention sowie zwi
schen verschiedenen Methoden unterschieden (Schulung und Trai
ning der Beschäftigten, praktische Übungen zu den Arbeitsver
richtungen, Ergonomie sowie kombinierte Ansätze zur Verbesse
rung der Arbeitsbedingungen). Auch wenn die Gründe bzw. Risiko faktoren für Rückenschmerzen bisher nur teilweise bekannt sind gibt es bereits hinreichende Kenntnisse für Aktivitäten, deren Auftreten zu reduzieren. Der Arbeitsplatz kann als geeigneter Ort für eine effiziente Entwicklung von Gesundheitsförderung angesehen werden. Vorliegende Studien werden hinsichtlich Stu
diendesign, Ergebnisvariablen und Interventionsmaßnahmen evalu iert und Hinweise zur Anlage zukünftiger Studien gegeben.
TABLE OF CONTENTS Page
FOREWORD 1
1 INTRODUCTION 2
1.1 Risk factors 3
1.2 Forms of prevention 8
2 REPORTED INTERVENTION STUDIES 20
2.1 Educational approach 25
2.2 Physical exercise approach 34 2.3 Improvement of work methods 43
2.4 Combined approach 46
3 EVALUATION OF THEIR DESIGN AND EFFECTIVENESS 62
3.1 Study design 62
3.2 Outcome variables 64
3.3 Intervention measures 67
3.4 Simultaneously acting other factors 70 3.5 Possibilities to draw conclusions 71
4 DISCUSSION AND CONCLUSIONS 76
5 RECOMMENDATIONS 81
5.1 Present action 81
5.2 Further research 86
6 BIBLIOGRAPHY 89
1
Foreword
The preparation of this report has been a difficult task, as prevention of back disorders does not fall only into the domains of the natural sciences. The lack of thorough intervention studies in this field may, to a great part, be due to the difficulties encountered when trying to combine different scientific disciplines. Most of the literature in this field has been published in the last decade, which indicate a growing interest in this matter.
Attempts to present back disorders have been reported primarily from Northern Europe, Canada, the United States and Australia.
The United Kingdom and the Netherlands have also contributed to the development of the present knowledge. In Germany, the interest in this question seems to have been quite limited so far, as measured by the number of reports published in scientific journals.
I wish to thank Taru Koskinen and Ritva Lehto for typing this report and Jacqueline Välimäki for checking the language.
Hopefully it will be of use when considering possibilities to further develop activities to reduce the occurrence of low-back disorders.
Turku, February 1992
Gustav Wickström
2
1 INTRODUCTION
The understanding of the mechanisms behind back disorders has developed step by step over this century. Studies on autopsy material gave the anatomical and histological basis for further investigation of physiological function. Experiments with autopsy material and evaluation of the effectiveness of various forms of pharmacological and surgical treatment have added to our knowledge, as have short-term human experiments and long
term experiment with animals. Since the 50s several epidemiological studies on the occurrence of back disorders in various populations have been carried out. The occurrence of disorders has been related to the risk factors these populations have been exposed to.
Thanks to the results of anatomical, physiological, biochemical, biomechanical, epidemiological, psychological and social studies we have today a picture of the risk factors predisposing to back disorders. However, due to the complicated structure of the back and to the lack of methods for continuous registration of changes in the soft connective tissues and the nervous tissues of the spine, many important questions still remain open.
Techniques, such as magnetic resonance, will add to our knowledge of the development of morphological changes in the spine during the present decade. And further development in measuring capacity is sure to come. There is, however, already now enough of a consensus on the significance of several important risk factors to allow purposeful attempts to reduce the occurrence of back disorders.
The evidence for pain-avoidance as a consequence of back pain is growing. It is no longer reasonable to look upon back pain as a benign, self-limiting conditon. Instead, it has to be recognised as what Waddell (1987) describes as a biopsychosocial model of illness behaviour, of epidemic proportions. The value in this pattern of behaviour appears to be the fear of pain.
3
Once the individual has suffered an initial attack, the next episode becomes three or four times more likely, and for two or three years recurrent spells of pain or repeated injuries are common. During this phase the individual tends to restrict his activities and is at risk of becoming fractionally weaker and stiffer. From that point onwards, he or she does that little bit less even though the musculoskeletal trouble becomes stabilised.
This is generally true of the back-pain patient (Troup 1988).
1.1 Risk factors
Episodes of low back pain can occur already at school age, but are most common between the ages of 20 and 40 years. Lumbar disc prolapses occur most commonly at 25 to 45 years of age.
Prolapsed lumbar discs are 1.5 - 2 times more common in males than females (Kelsey et al 1990).
Posture and flexibility
Body height was related positively to the prevalence of sciatica (Heliövaara et al 1991), while the influence of body weight is small or negligent.
Moderate postural discrepancies, such as lateral curvature of the spine or pelvic tilt, do not appear to increase the risk of low back pain. Restricted forward flexibility is associated with a decreased risk of subsequent low back pain, probably indicating that a more stable lumbar spine is less susceptible to injury.
Trunk muscle strength
Back and abdominal muscle strength and fitness seem to protect against back injuries by alleviating at least part of the mechanical stresses on the spine.
4
Creep
During the recumbency of sleep, the loading on the intervertebral discs is reduced. They absorb fluid and increase in volume. The absorbed fluid is expelled during the day when the loading of the spine is increased. There is, thus, a diurnal variation in the fluid content and height of the discs which causes a variation in the mechanical properties of the spine.
Light manual labour for six hours causes disc height to decrease by 1.5 mm. The height loss is rapid at first but much slower by the end of the six hours. If the compressive force is increased, the height loss is greater. The average diurnal variation in human stature is about 19 mm, which corresponds to a change of about 1.5 mm in the height of each lumbar disc. Changes in disc height are caused by fluid exchange and creep deformation of the annulus fibrosus. Creep loading increases the disc's compressive stiffness. It determines how much the disc and surrounding soft tissues deform during physiological dynamic loading of the spine. In extended postures, compressive creep loading can result in stress of the apophyseal joint surfaces (Adams et al 1990).
Heavy loads
Workers, handling heavy weights manually, are more likely to experience low back pain and prolapsed lumbar disc than other workers. An occupation with an exceptionally high rate of back injuries is truck driving. More than half of the injuries occur in association with loading and unloading trucks. Another occupation at high risk is that of nurses, who lift seriously ill patients in hospital wards.
It appears that freguent lifting of objects weighing 15 kg or more is associated with an increase in risk. Evidence from biomechanical studies is consistent with epidemiologic findings,
5
in that the likelihood that a disc will fail is increased when torsion is superimposed on annular fibers already under tension from compression of the nucleus of the disc.
Sitting
The studies on sedentary occupations and back pain are difficult to interpret. Some studies, but not others, show an association between jobs that require prolonged sitting and risk of low back pain or prolapsed disc.
Driving
Many studies have found that driving motor vehicles is associated with an increased risk of low back pain and prolapsed disc. Possible mechanisms for this association include vibratory stress on the spine, lack of proper support for the back, poor positioning of the legs, shifting of gears, and the driver's lack of freedom to alter substantially the position of the spine.
Injury
Underfoot accidents are a continuous and epidemic cause of back injury. Slipping is a major cause of injury to the lumbar spine.
Outdoor accidents on snow and ice occur during winter time.
Indoor injuries are caused by objects and liquids on the floor.
The fractions of sciatica and LBP attributable to back injuries have been estimated to be 17 % and 14 %, respectively
(Heliövaara et al 1991).
Smoking
Several studies indicate that people who smoke cigarettes have an increased risk of low back pain and prolapsed disc. Current
6
smokers have almost twice the risk of prolapsed lumbar disc compared with those who have never smoked or who are former smokers. Greater disc degeneration is present in the lumbar intervertebral discs of smokers, compared with nonsmokers. The effect is present throughout the lumbar spine, implying a mechanism that acts systemically (Battie et al 1991).
Psychosocial Factors
Psychosocial factors affect the reporting of low back pain and recovery from low back pain. However, the role of psychosocial factors in the etiology of low back pain is less clear.
Psychosocial characteristics such as anxiety, depression, psychological stress, alcohol and tranquilizer use, feelings of monotony at work, and dissatisfaction with a job are associated with low back pain. But it is not known whether these psychosocial characteristics predispose to low back pain or whether having low back pain contributes to the development of these attributes.
In cases of tissue injury pain, when pain behaviours persist past healing time or in the absence of significant physical findings, the tendency has been to attribute this to personality or motivational factors within the patient. The term psychogenic pain is usually invoked and the inference is drawn that the pain problem now arises from processes within the person's mind.
Socioeconomical factors
In determining factors that promote or inhibit chronicity, claimants of chronic disability (90 days or more) were contrasted with claimants of short-term disability (14 days or le s s ) . Women were less likely to file a claim, but when they did they were more likely to be chronic claimants.
7
As age increases, so does the chance of chronicity, while wage level is inversely related to chronicity. Thus socioeconomic factors are clearly implicated in chronic back sprain:
* Age (claimants over 40 years of age ran twice the risk of claimants 25 years old or younger)
* Monthly wage (claimants earning $ 1.000 or less in 1984 ran twice the risk of claimants earning more than 2.000 USD)
* Family status (divorced or widowed claimants with no children ran twice the risk of single claimants with no children).
Compensation
Insurance policies regarding back injury attributed to work vary greatly from one country to another, and even inside some countries.
Back sprain may be diagnosed once fracture, infection, neoplasm, and ruptured disc are excluded. The diagnosis depends on the patient's complaint of low-back pain and the absence of neurologic and mechanical signs. The tissue damage that might occur at the time of onset of a back sprain cannot persist for years as the cause of disability, as the human body heals its wounds. On the other hand, signs of myofascial pathology have been described in chronic back pain patients. The relationship between any physical findings and chronicity of back sprain remains problematic.
In the State of Washington, U.S.A., 2 % of the total covered
labor force filed a claim for back sprain. 16 % of all
industrial insurance claims were for back sprain; 107 million
USD was disbursed to back sprain claimants and their health care
providers (Volinn et al 1991).
8
1.2 Forms of prevention
Many of the risk factors for low back pain and prolapsed disc identified to date are amenable to preventive measures, either through modification of the environment or through changes in personal behaviour. Because occupational activities contribute substantially to the development and course of low back pain, modification of factors in the work site is an important approach to the prevention of low back pain.
One approach is careful selection of workers for jobs that involve heavy manual work. Although low back x-rays and medical examinations have not proved useful as routine screening tests for selection of workers, some studies suggest that selection on the basis of muscular strength testing for specific jobs can reduce the likelihood of a back injury.
Another important aspect of prevention is reducing the likelihood of chronic disability in people with low back pain.
Although no definitive evaluations have been carried out, available evidence suggests that back schools are effective for patients with back pain of recent onset, but not for those with chronic back pain. It is important that most people return to work as soon as possible after the onset of the back pain. When they return, however, they should in the beginning avoid lifting heavy objects, bending, twisting, sitting in low chairs, and maintaining in the same position for long periods of time
(Kelsey et al 1990).
The main goal of a Swiss national program is to investigate the process leading to chronic low back pain. The rapid increase of disabling low back pain in the recent decades is considered to prove that factors outside the spine are responsible for this process. These factors are changes in lifestyle and interpersonal relations, as well as in society and the health-
9
care system. From these factors means of prevention will be derived (Keel et al 1990).
However, the evidence that musculoskeletal pain can be prevented is epidemiologically slim. Of the recognised preventive approaches, ergonomics is beyond doubt the most fundamental.
Only recently, however, has any convincing evidence emerged that this approach can bring cost benefits. The costs should be balanced by savings arising from increased productivity, reduced job turnover, fewer work stoppages and lower medical costs. It is now accepted that it is a waste of time to train only recruits and ignore supervisers and managers. And it is axiomatic that the practical instruction should be at the place of work and not in a classroom (Troup 1988).
A study designed to explore the value of anamnestic and clinical data to predict recurrence of low back trouble has shown that the determinants have complex interrelationships, variously acting in combination to influence the course of the disorder.
Even so, a high level of predictability can be achieved in nonspecific LBT.
Primary prevention
The Cochrane Report by the Working Group on Back Pain (Cochrane 1979) noted that whilst primary prevention of back pain would be the ideal method of controlling the problem, such an approach is hampered by the generally unsatisfactory state of present knowledge. Although instruction on manual handling and lifting is fairly widely believed to have prophylactic value, there is no scientific evidence that it is, in fact, effective in reducing the frequency or severity of back pain.
So far as back pain is concerned, the first attack is the ideal
time for active and perhaps aggressive treatment. But if it is
tacitly assumed that the vast majority of patients recover from
10
back pain, whether or not they are treated, then the opportunity nay be nissed. The problem rests with those who have a duty to offer primary care - the general practitioners and the occupational health physicians, as well as the physiotherapists working in community and occupational health. And the main problem is time.
Once it is appreciated that many of the commoner musculoskeletal disorders have a multifactorial aetiology, that often they are manifestations of illness behaviour, the need for a full and comprehensive diagnosis rather than a mere diagnostic label becomes obvious.
Patients must be listened to and a clear picture elicited of what their activities normally consist of, and of how the pain affects them. Patients appear to welcome what they perceive to be a thorough examination. And this takes time, a diminishing commodity in the health services of today. Yet the investment in time for these patients, particularly in primary care, is likely to be cost-effective. For the health services this will be a major challenge. The need for a rapid expansion of physiotherapeutic services in occupational health and in the community is now clear (Troup 1988).
The methods to prevent low back disorders vary somewhat according to the age of the target group. As back pain may be experienced already in childhood, preventive efforts should begin in elementary school by arranging some physical exercise every day, by avoiding continuous sitting and by acquiring chairs and tables adjustable to the height of the pupils. In vocational training, active attention should be paid to the loads on the low back in all trades which involve hazards to the back tissues.
As low-back disorders are especially common in working age, and symptoms are often related to work in one way or another, most
11
attempts to reduce the occurrence of LBP have been made in occupational settings. According to Snook (1987) two different but interdependent strategies of measures have been developed to prevent low-back pain in industry:
a) measures to assure that the worker who performs activities that stress back tissues significantly is appropriately evaluated and trained for such work, and
b) measures to assure that the work place and work tasks are arranged in ways that minimize injurious stresses to the low back.
Also Chaffin (1987) emphasizes the two different, but dependent strategies that must be developed to prevent low-back pain in industry. One is of an administrative nature and is concerned with whether the worker who performs activities that stress back tissues is appropriately evaluated and trained for such work.
The second strategy is of an engineering type, dealing with methods to ensure that the workplace and work tasks are specified in ways that minimize injurious stresses to the low back. He underlines that both of these strategies rely on knowledge of the biomechanical requirements of a job.
The measures directed toward workers consist of selection and placement, education, and fitness training. All these activities require knowledge also of the work and the back loads it involves.
Selection and placement
Reported previous back symptoms and pathological clinical findings are used in health examinations to exclude people with clearly elevated risk of back symptoms from occupations known to involve risks of low back pain. However, the criteria for
"elevated risk" are not very clear.
1 2
Testing for muscular strength can be used as a preventive approach, at least for low back injuries, as people with weak muscles have been found to run a three times higher risk of low back pain than people with strong muscles, in jobs requiring lifting and carrying. The testing procedure should preferably be specific to the job (Chaffin et al 1978).
For pre-employment medical screening, there is no epidemiological evidence. There are few tests of working capacity that have predictive value for the first attack: either anthropometric or strength tests. One exception is an endurance test of back-muscle strength and another is the 'situp' test of dynamic trunk flexor strength, though neither test has been studied in an industrial environment (Troup 1988).
The radiographic methods in routine use at present are not suitable as screening tools. In addition, the correlation between radiographic abnormalities identified on x-rays and the risk of low back pain is weak, with the exception of severe degenerative changes and spondylolisthesis. The examination exposes the work applicant to ionizing radiation. Thus radiographic examination should be used only when indicated by anamnestic and/or clinical findings.
Education
The basic structure and function of the lumbar spine should be explained to everyone entering a job which involves risks of low back pain, and not only to those who are required to do heavy lifting.
The importance of lifting heavy loads with straight back and bent knees has been emphasized over the years, while some have criticized this approach as too simple. Nowadays the idea of lifting with a straight back is not adhered to as an absolute
13
principle, as, in certain circumstances, it may cause higher loads on the spine than lifting with bent back. The present recommendations for reducing hazards in heavy lifting may be summed up as follows (Chaffin 1987):
- do not lift from floor level
- avoid twisting and lateral bending when lifting - keep the load close to the torso
- move the load in a planned way, to minimize unexpected motion.
The aims of training for safety in lifting is to make the workers aware of the dangers of careless and unskilled lifting and to show them how to avoid unnecessary stress. Training at the workplace should include the use of the particular tools and machines employed in the job and instructions on how to use them with minimum risk for the back.
Advice as to postural loads and vibration is seldom given.
Without being able to base guide-lines on solid scientific evidence, recommendations could at present tentatively be formulated as follows:
- prolonged sitting, especially while driving a vehicle, should be interrupted once an hour by standing up, stretching, and preferably walking, to enhance the nutrition of the lumbar tissues,
- prolonged working in awkward postures should be interrupted at suitable intervals to permit restoration of muscle and ligament function,
- the gravitational load on the lumbar discs should be relieved
by lying down in the middle of the day for 5 - 1 0 minutes.
14
Active exercise
Continuous sitting at work, travelling to and from work, as well as at home, results in weak trunk muscles and short hip flexor muscles. Active exercise is required to improve the function of these muscles and to enhance nutrition of the intervertebral discs. Even ordinary walking is beneficial, while active training of abdominal, back and hamstring muscles probably further diminishes the risk of low back disorders.
Ergonomic measures
The work should be planned and arranged in such a way that frequent or prolonged adoption of forward-leaning, forward-bent and/or rotated postures can be avoided. In manual handling of materials and goods the demands on the working postures are even greater. Special attention to the carrying and lifting conditions should be paid when the weights handled weigh 20 kg or more. When feasible, mechanical equipment to transport the material should be used.
For those working in standing postures, possibilities to walk, sit and/or lie down at times should be provided. When the work is carried out sitting, possibilities to vary sitting postures are important. Any vibration of the seat should be as small as possible.
To sum up, work should involve alternating dynamic and static back loads. If alternation of loads is not feasible, short periods of rest and/or suitable exercise should be introduced in the work cycle.
Over-exertion injuries and disorders, such as low back pain, have been associated with six ergonomic risk factors which are found in a broad spectrum of manufacturing and service jobs: 1) forceful exertions, 2) awkward work postures, 3) localized
1 5
contact stresses, 4) whole-body or segmental vibration, 5) temperature extremes, and 6) repetitive motions or prolonged activities. A structured job analysis procedure has been developed by Keyserling et al (1991) to assist occupational health and safety professionals. The purpose of the job documentation is to develop a complete description of how the job is performed. This description serves two major functions:
1) to assist the job analysis team in identifying risk factors and 2) to establish baseline measurements which can be used to evaluate the effectiveness of ergonomic changes. Because work methods and job demands usually change over time, it is essential to record the date and time of the analysis.
It is important to use consistent job identification methods including:
- job title
- job code number - department
- physical location in plant
- any other identifying information.
On some jobs, the ergonomic stresses may differ from hour to hour or from day to day, depending on the specific part that is being handled or produced.
Description of the major purpose of a job, the work schedule, the number of work cycles per shift, possible job rotation, the workstation layout, tools, equipment and materials used, as well as the work methods is desirable.
Once the significant risk factors have been identified, the next step is to reduce these risks to acceptable levels. The appropriateness of different intervention strategies, such as the redesign of equipment, processes, and/or work methods, will vary between and within facilities. Changes which are practical
16
and economically feasible at one workstation may not be appropriate for other workstations. Alternative solutions must be evaluated in order to determine the best intervention strategy for each situation.
Selection of a method for reducing or eliminating ergonomic stresses does not end the job analysis process. It is frequently necessary to modify the recommended changes in workstation layout and/or work methods to ensure that the proposed solution works as intended. Where feasible, the proposed solution should first be implemented on a prototype basis. The job analysis procedures described above should then be used to make certain that all ergonomic stresses have been ameliorated as intended and that no new stresses have been introduced. After the control measures have been fine-tuned and implemented on an operational basis, another job analysis should be performed to ensure that the solution is working effectively (Keyserling et al 1991).
Accident prevention
External forces causing sudden, unexpected rotation, compression or shear of the lumbar tissues should be avoided as far as posible. To achieve this, it is not enough only to reduce the risks of severe injury, such as blows and falls. Also smaller injuries, arising from stumbling or slipping on uneven or slippery surfaces, should be prevented. As the risks of unexpected sudden movements is greater when handling weights, attention should be paid to the grip of the hand to the weight and the grip of the feet to the floor.
For low back injuries, intervention efforts should centre on prevention of falls. This approach would have the additional benefit of reducing other potentially serious injuries in addition to those of the low back. The most frequent contributory factors for falls resulting in low back injuries include slippery work surfaces, loss of balance, and the need to
17
climb. Each of these risks suggests specific countermeasures.
When planning prevention it is important to focus on the injury event ’’falls” rather than on injury of a specific body site
(Clemmer et al 1991).
Controlling the cost of back injuries in the workplace depends on controlling or preventing the small proportion of high-cost injuries. However, data suggest that it may not be feasible to target high-cost injuries selectively because, for the most part, they are indistinguishable in their genesis from low-cost injuries. Rather than attempting to control high-cost back injuries, it would be more feasible to focus on subsets of back injuries defined, by an injury event (eg. a fall) or an activity (eg. lifting sacks). These injuries might be controlled through modification of the work environment, equipment, or specific work procedures (Clemmer et al 1991) .
Secondary prevention
Prevention of possible future back pain in people who never have experienced any at all is difficult to motivate, whereas people who have personal experience of back pain are usually interested in learning ways to avoid further trouble. Too much emphasis on primary prevention may thus be a waste of resources which instead could be directed to early, and intensive secondary prevention. This activity goes hand in hand with therapeutic efforts or starts immediately the period of treatment finishes.
Active secondary prevention would probably save many patients from being afflicted with chronic low-back disorders.
Pain from tissue injury persists into chronicity largely because of failures of the health care system to apply what is known about the healing process and the adverse effects of disuse.
These failures in turn interact with patient misconceptions about the nature of pain and healing. The result is a
18
confounding of pain with suffering and an unnecessary persistence of pain and disability (Fordyce 1987).
The perception of tissue damage requires that the brain both record that there are incoming nociceptive signals from the injured body part and interpret or attach a meaning to those signals. Were there suddenly to be unexpected and not immediately identifiable noise close by (e.g. a helicopter hovering over the building), instantly, I could not continue my task. As soon as the noise has been identified as not posing a threat, I can put the sound into the background and continue with the business at hand. This illustrates that the cortex can override incoming signals if it can identify them as not holding dire consequences for the future.
Consider the example of an American football player being knocked flat by a defensive tackle. Is there pain? Of course there is and yet the player gets up and is ready to continue within 15 sec. This sequence can be repeated 20 - 30 times in a game, without significant limitation of function. There is pain, but not suffering or limitation. This illustrates that intensely painful stimuli do not necessarily have a widespread influence on subsequent behaviour. In the special case of the football player, long years of experience have taught him that the pain he feels does not imply threatening structural or tissue damage.
Programs designed to prevent back injuries must reach the total
work force. However, only about 2 % of an average work force
report a back injury yearly, and only 10 % of those injured
(2/1000 workers) make up 80 % of the costs. Thus, even with an
effective means of preventing back injuries, it may be difficult
to show cost effectiveness. To date, scientific efforts indicate
that the greatest opportunity to reduce the impact of back
problems on individuals and society probably lies with the
prevention of back pain disability through appropriate medical
care.
19
According to Bigos and Battie (1987), the collective use of proven treatment methods during the acute stage of back symptoms markedly reduces the period of time patients are disabled by back problems. Effective early intervention should centre around: (1) teaching patients about back care, including how to control symptoms through improved body mechanics; (2) applying these educational principles, specifically to the patient's livelihood; (3) avoiding the debilitation that results from overusing bed rest and medication.
In the absence of bone or joint instability, it is ideal to begin programs to increase endurance and stamina as soon as possible. Activities for cardiovascular endurance training, such as speed walking, cycling, swimming, or even jogging at therapeutic intensities can usually be done early in the recovery period.
Informing patients about the benefits of endurance training, beyond helping to avoid long-term back problems, can be used to help motivate patients to comply with their exercise programs.
Regular endurance exercise has been shown to improve cardiopulmonary function, sleeping habits, and mental alertness, as well as reduce psychologic stress, depression, and pain complaints. Conversely, psychologic consequences associated with inactivity, including depression and lowered self-esteem, can be avoided. The patient should understand that the goal is to condition the back and improve overall health through regular, moderate, aerobic activity.
Recommendations on how to keep the back tissues fit and how to best use the back have been published in popular form by clinicians with through experience of rehabilitation and ambulatory treatment (Cailliet 1984, Imrie 1983). The latter author has introduced a standardized fitness test to evaluate
2 0
progress in back tissue function. The concomitant exercise program requires:
- exercise for five to ten minutes daily, for at least two weeks - marking number of exercises in charts
- weekly retesting of back fitness.
2 REPORTED INTERVENTION STUDIES
There are quite few work-related intervention studies aimed at reducing the occurrence of low back disorders to be found in the scientific literature. The articles to be found are not easy to classify according to level of prevention (primary, secondary, tertiary) or to method of approach (educational, physical exercise, ergonomics).
Most of the published studies deal with the possibilities to teach nurses ergonomic working methods. Very few studies have been carried out in industry. Nearly all reported studies have been carried out in the 80s or 90s, which indicates a growing interest in prevention.
Not all the studies reviewed have been carried out in occupational settings, but all of them should be of interest when considering the possibilities to prevent work related low back disorders. The studies will be presented according to measures of intervention. Thus, they are divided into those emphasizing educational methods, those emphasizing physical exercise (combined or not combined with other forms of education), and those emphasizing improvement of the working conditions (combined or not combined with education and/or physical exercise). See Table 1.
Table 1. Reported intervention studies aimed at reducing the occurrence of low back disorders Author(s);year Design
Berwick et al;
1989
Dehlin et al;
1978
Donchin et al;
1990
Elnaggar et al;
1991
Randomized trial;
two intervention g r o u p s , one
control group
Trial; two inter
vention groups and one control group
Randomized trial;
two intervention g r o u p s , one
control group
Randomized trial;
two intervention groups
Population ;N Intervention measures
Outcome variables
Results
Adults with at least 2 weeks duration of low back pain;
74,72,76
Psychoeducational back school
Pain (visual analogue scale) Sickness (impact profile)
No measur
able ef
fects on comfort or functional status
Nursing aides;
13,14,14
Information, muscle training
Back symptoms, psychological perception of work
Increased muscle
strength, more posi
tive per
ception of work
Hospital em
ployees with at least three epi
sodes of low back pain;
46,46,50
Flexion exercises Back School
"Painful months"
(reported)
Reduced occurrence of low back pain
Patients with chronic mechani
cal low back pain; 28,28
Flexion and extension exer
cises
Severity of low back pain
Reduced se
verity of low back pain.
Increased thoraco
lumbar mobility
to
A u t h o r (s );year Design Population;N Intervention measures
Outcome variables
Results
Greenwood et al; Randomized trial; Coal miners; Counseling, Length of sick- No signi-
1990 experimental and
control group
121,163 coordinate care, special services
leave disability benefits paid, medical benefits paid
ficant results
Keijsers et al;
1989
Randomized trial;
intervention and control group
General popula
tion volunteers with low back pain; 14,16
Information on pain, anatomy and psychology
Pain Increased
capacity to cope with pain Kellett et al; Randomized trial; Kitchen furni- Regular group Short-term sick Decrease
1991 intervention and
control group
ture workers;
58,53
exercise leave in sick-
leaves Kraus et al;
1983
Pre- and post
testing, no control group
Volunteers with long experience of low back pain;
11809
Regular physical exercise
Pain Reduced
occurrence of pain Linton et al; Randomized trial; Nurses with back Physical and Pain intensity, Reduction
1989 intervention and
control group
pain; 36,30 behavioural therapy
fatigue and anxiety
in pain intensity, fatigue a m anxiety Manniche et al; Randomized trial; Patients with Back muscle Pain, disability Reduction
1988 two intervention
groups and one control group
low back pain;
32,31,27
exercise and physical impairment
of pain a m physical
impairment
hJ
A u t h o r (s);year Design Population;N Intervention measures
Outcome variables
Results
Reilly et al;
1989
Trial; one in
tervention and one control group
Patients with low Physical exercise back pain;
20,20
Pain, aerobic fitness, muscu
lar strength
Decrease in pain
Ryden et al;
1988
Unclear Hospital
employees; only rates presented
Education, light duty alternative
Incidence and costs of back injuries
Decrease in inci
dence and costs of injuries Sirles et al; Trial; no control City employees Education in back Trunk muscle Increased
1991 group with low back
injury; 74
structure and function, physi
cal exercise
strength flexi
bility, pain, psychological well-being
muscle strength and flexi
bility, decreased anxiety Stubbs et al; Trial; no control Student nurses; Training in Intra-abdominal No effects
1983 group 8 patient-handling pressure, back
pain
observed Versloot; Trial; one in Bus drivers; Education on Back problems, Increase in
1989 tervention and
two control groups
200,200,100 coping, body mechanics, relaxation, training
sick-leave sick-leaves in control g r o u p , but not in in
tervention group
Wollenberg; T r i a l ; one in Industry Education physi Body mechanic Improvement
1989 tervention and
two control groups
employees;
31,13,14
cal exercise performance in some groups
N)
GJ
A u t h o r (s);year
Design
Population;N Intervention measuresOutcome variables
Results
Wood;
1987
Two trials;
control group
Hospital
employees with low back injury approx. 700
Administrative changes, ergono
mic counseling
Back injury claims
Videman et al;
1989
Wickström et al;
1991
Trial; one in
tervention and one control group
Trial; five in
tervention and two control groups
Student nurses;
138,105
Training in patient-handling
Pat ient-handling skill, back
injuries
Reduced accident rate in both inter
vention and control groups No clear effects
Metal industry employees;
76,74,70, 155,119, and control group
Improvement of working condi
tions, physical exercise,
education
Reported pain, sick-leave, physical work load
Improved work m e t hods , redu
ced physi
cal work load, redu
ced occur
rence of pain
to
25
2.1 Educational approach
Pain is a subjective experience and can only be perceived by the sufferer. The experience of pain can be described by location, intensity, temporal aspects, quality, impact, and meaning.
Factors that contribute to the experience of pain include psychosocial, economic, and cultural contexts. The life experience of a person influences the verbal and nonverbal expression of pain.
An individual experiencing nonmalignant chronic low back pain may exhibit preoccupation with pain, passivity, inability to deal with anger and hostility, feelings of isolation and loneliness, and use of pain as a symbolic means of communication. Pain and suffering may become an integral part of a patient's personality (Aronoff, cited by Smith et al 1990).
In chronic nonmalignant pain nociception is no longer the driving force, because healing of soft tissue has occurred.
Often viewed as "not real pain", health care practitioners are frequently less sensitive to the needs of this group of people.
Traditional pharmacologic management is no longer totally effective in pain relief, since nociception is not a primary issue. The pain experience at this time is influenced to a great extent by the levels of endogenous opiates and the interpretation of the pain experience.
The key to understanding chronic non-malignant pain is to appreciate the relationship of pain to suffering (Figure). The events occurring at the cortical and thalamic level can be modulated by non-traditional approaches such as relaxation and distraction.
Suffering is a process whereby the unrelenting pain perception produces fear and anticipation of pain. This leads to worry, depression, and ego-centricity, which further contributes to the
2 6
perception of pain intensity. The individual is often trapped in a powerless cycle of worry and anticipation, that manifests in patterns of pain behavior characterized by low motivation, manipulation, inactivity, and narcissism. The pain has taken control of the patient. The goal of the treatment must be for the patient to take control of the pain.
Non-traditional interventions
Non-technologic modalities include the use of distraction, relaxation, therapeutic touch, enhancement of spirituality, maximizing social support and behavioural therapies. These
interventions are not costly and can be integrated into one's daily activities following appropriate instruction. Nurses are in key positions to influence these patients and stress to them the need for taking control of their pain through the use of these non-technological modalities.
Support groups provide patients experiencing chronic pain with the opportunity to share their experiences, receive information on the supraspinal modalities, and practise these techniques with supervision and peer support. The support groups for individuals with chronic pain can achieve results in an 8- session period. The priority in beginning group sessions is to encourage individuals to share their pain situations and perceptions of suffering. This not only facilitates socialization but also highlights to the participating individuals that they are not alone and that others are experiencing similar situations. There is a cathartic therapeutic effect in verbalizing one's stressful story of suffering. Individuals may compare their situation to that presented by others. This social comparison can provide relief as group members compare and contrast their individual circumstances (Smith et al 1990).
2 7
Chronic low back pain (pain that lasts longer than 6 months) is increasingly being regarded as a problem that develops and is maintained by the interaction of physical, psychological and social factors. These factors are of equal importance in terms of treatment. In the United States a number of pain management programs have been developed where patients actually "learn to live" with their pain problem. Many of these programs have produced fair to good results. Cognitive and behavioural elements constitute an aspect of these pain management programs.
The cognitive element is directed at thinking about pain, the behavioural element at what the patient and his environment do with the pain.
The importance that an individual attaches to a particular situation, and his/her present psychological state contribute significantly to the pain experience. The gate-control theory describes the pain experience as the result of a complex interaction of sensory-discriminative, affective-motivational and cognitive-evaluative systems. In addition, the physiological mechanisms of pain have multiple afferent and efferent effects;
the ascending and descending neuronal systems modulate the nociceptive input. The theory offers a neurophysiological basis for the role of psychological factors in the pain experience. In the behavioural approach to chronic pain it is assumed that these psychological factors are partly responsible for the maintenance of pain.
A distinction must be made between pain and pain behaviour. Pain is an unpleasant sensory and emotional experience which is associated with real or potential tissue damage, or which is described in terms of such damage. A pain experience is something which one can only recognize indirectly by observing the facial expression, posture and speech of the person who is in pain. These are the pain behaviours and they, like any other form of behaviour, are determined by the consequences they produce. If pain behaviour is "rewarded", it eventually becomes
28
controlled by the rewarding consequences. Rewards for pain behaviour include receiving attention, support, and care when one has pain. The avoidance of unpleasant events can also be a reward for pain behaviour, since pain often means no more threatening social contacts and fewer responsibilities.
Coping behaviour refers to the manner in which someone reacts behaviourally, cognitively, and emotionally to circumstances that require adjustment or adaptation. Though somewhat over
simplified, one could say that the experiencing and expressing of chronic pain complaints is, itself, a sort of coping behaviour. The patient reacts by means of pain to circumstances that require adjustment.
Of considerable importance in the maintenance of chronic low back pain, is the activity level of the patient. The most important physical deficiency is, in many cases, the deconditioning syndrome that is caused by prolonged inactivity of the back muscles and joints.
The Maastricht Back School offers an education and skills program in a group setting for patients with chronic low back pain. The program consists of eight lessons, concerning pain history, pain, back structure/causes back pain, posture and psychological factors.
In an environment, which reacts in a less concerned way, somatic fixation decreases. Patients are able to cope more actively with their pain and seek less social support. The severity of the pain is diminished and pain seems to interfere less with daily
life (Keijsers et al 1989).
The patients who reacted favourably to a back school programme could be described as emotionally well adjusted, showing relatively good cognitive capacity with undisturbed reality testing. Patients showing spontaneous recovery in the control
29
group were also characterized by a more lively and less controlled way of expressing emotions and effects (Julkunen et al 1988).
Back schools in industry have to be tailor-made for particular groups of employees, not only with regard to the contents but also to the language used, the time spent, practice and slides.
Slides used as examples worksites, so that the identification with the
have to be made at the particular employees recognize themselves and back school programme occurs. The information has to be stimulating and entertaining. Positive reinforcers have to be used; for example, if you use your back correctly you will have more energy left for leisure, or if you train and exercise you will have a better physical condition and you will do your job more easily.
Classes, to be given in company time preferably at the beginning of a shift and if possible at the worksite, should not exceed 15 employees. The programme should include:
(a) Anatomy of the back and good posture.
(b) Body mechanics during rest and activities at work and at home.
(c) Practice of job specific activities.
(d) Psychological factors, such as motivation, stress, accident- proneness.
To be really effective regular refresher classes should be given every 6 months (van Akkerveeken 1985).
In a study designed to evaluate a back school training programme on life style and nutrition, back care and physical fitness, and stress and relaxation, 200 bus drivers were chosen at random to serve as the experimental group. Another 200 drivers were chosen to serve as a control group and a further 100 were selected to form an extra control group to find out if the regular control group was affected by the "Hawthorne-effeet". The back school
3 0
programme was presented three times to the experimental group with a six month interval between the sessions. Three months after each session the status of both the experimental and the control group was assessed by means of a questionnaire.
The bus drivers were interviewed using a mixed open and structured technique. They were also observed during their work, with the aid of photography. The sessions treated responsibility for one's own health, mind-body interaction in relation to illness, body mechanics, sport, working posture, etc. How to recognise and how to cope with stress was discussed and relaxation-training was given.
Because bus drivers are not accustomed to teaching situations, a relaxed and informal atmosphere was created. The language used was related to their level of education. The process of influencing attitudes is greatly affected by the person who gives the training. Other situations and trainers will yield other results.
We conclude that the change in the difference between the incidences of sickness leave is due to the back school p r o gramme.
After the training programme the drivers more frequently changed sitting posture when driving the bus, and increased walking around and doing some exercises during the short breaks in the shift. The incidence of sick leave did not decrease in the experimental group, but it increased in the control group. This result was probably achieved by the training programme (Versloot 1989) .
In a prospective trial, 222 adults with low-back pain of at least 2 weeks' duration were randomly assigned to a) usual care, b) 4-hour back school or c) 4-hour back school plus a 1-year
"compliance package" program designed to encourage appropriate
31
self-management for back pain. With or without follow-up encouragement, back school instruction given in one 4-hour session had no measurable impact on either comfort of functional status. The lack of interest in participation was seen already in the pilot phase. It was considered to be due to the low level of pain experienced by most subjects. Poor attendance at the initial plan of four successive 2-hour sessions resulted in them being replaced by a single 4-hour session (Berwick et al 1989).
Harber and co-workers carried out a study focusing on the attitudes and beliefs of nurses themselves about the causation and prevention of back pain. Four nursing units were selected for participation to provide a representative sample of in
patient nursing activities; these included a medical, a surgical and a pediatric unit. A semi-structured format was utilized for the interviews with 68 nurses. Interviewees were asked to identify tasks which they believed could produce back pain, in addition to those tasks which actually produced it in the individual respondent. Two general types of questions concerning prevention were asked: "What do you do...", and "What should be done ..." to prevent occupational low back p a i n ? . Three summary categories were developed: personal actions, specific work practices, and environmental change. Personal practices at the workplace and at home constitute the majority of the preventive methods which the nurses report they "do". These included personal exercise, relaxation drug treatment, support shoes, and health practitioner visits. Work practices produced nearly as many responses, including mentions of body mechanics and of seeking assistance. The "should" responses emphasized work practices, with most suggestions including more staff, better training, more men and more exercise.
Nurses believe that tasks involving patient transfer account for occupational back pain. Prevention is believed to be primarily a function of personal practices rather than addressing environmental determinants of back pain. Many nurses focus on
32
administrative controls such as staffing changes to decrease the impact of back pain. This emphasis on the worker's own responsibility for preventing back pain either by work practices or personal choices contrasts with a more balanced approach generally suggested by empirically based research studies and recommendations for injury prevention. Unlike many industrial workers, nurses must complete task-specific training in nursing school prior to beginning their job. This training, which is a major part of the process of socialization into the health care enterprise, might introduce a set of beliefs which is retained throughout the professional career.
Nurses' credence in prevention through personal actions may also reflect a general orientation of nurses as health professionals, rather than as "industrial workers". Nurses often counsel patients to modify their personal health practices to improve their health; this approach may be generalized by the nurses to their own occupational health. As health professionals, the nurses may consider the care of the patient to be so overwhelmingly important that any focus on changing patient care practices to affect their own discomfort level would be socially, ethically, and professionally unacceptable (Harber et al 1988).
To produce a cascade effect of information, nurses who attended a two-day course in patient handling became "back care facilitators" within their ward team and were awarded certificates of competence in patient handling techniques. The facilitators were asked to teach back awareness and patient handling techniques to all members of their ward team. This proved difficult to accomplish, as nurses were reluctant to admit that they had back pain, or had suffered back pain previously (Gonet and Kryzwon 1991).
In New Zealand, the Accident Compensation Corporation, faced with mounting back injury statistics, decided to mount a bold
33
experiment in an attempt to change p e o p l e 7s indifference to good lifting and bending techniques, and the way people thought about their backs. A nationwide television campaign, aimed at increasing awareness of the importance of back care, was carried out. It introduced the whole population, particularly school- children, to better bending and lifting, without making them apprehensive about these activities. And it motivated public acceptance towards a sense of personal responsibility for back injury prevention. The most important elements in safe lifting and bending were first determined. The result was simplified into a short message, which could be utilized as an easily remembered catchy slogan: "Bend your knees, your back is not a cr a n e ."
The first phase consisted of interviews with 1,000 subjects randomly selected. The second phase was a series of one minute advertisements shown at peak viewing periods during the day, motivating people to bend their knees whenever they go towards the floor, regardless of whether it is to lift objects or put them down, and then promoting some simple exercises. The advertisements ran for three months. Television interviewers, who used "bend your knees" as a theme for public discussion added excitement to the campaign. The final phase was again interviewing the original 1,000 subjects to determine whether any of the old attitudes towards back injury prevention and lifting and bending techniques had changed. 97 % recalled promotion or information, 92 % said they had seen it on television. The corresponding figure preceding the campaign was only 22 %. 88 % claimed that seeing or hearing promotional material had affected the way in which they treated their backs.
The national television network was so impressed with the value of the program that they donated a great deal of air time to free advertising as a public service (Ring 1989).
34
2.2 Physical exercise approach
Kraus et al (1983) have reported the results of a nation-wide exercise program to reduce the occurrence of back pain. A six- week program was established at the Young Men's Christian Associations (YMCAs) throughout the United States. 11,809 people completed the exercise program in 800 YMCAs in 50 states. The classes met twice weekly and were conducted by specially trained instructors. Each class was limited to 15 people so that the instructor could be sure that each person exercised correctly.
On days when the class did not meet, each participant exercised at home, performing only those exercises taught by the instructor.
The program included relaxation exercises - which are usually not a component of prescribed back exercises - and a gradually increasing sequence of limbering, strengthening and stretching exercises, all limited to three repetitions at a time. The exercises provided a warm-up and culminated in a workout or, by reversing the sequence, served as a cool-off. New exercises were added one by one over a 12-session period.
Before the first exercise session, each person was evaluated by means of a six-item test and a pain questionnaire eliciting information about the intensity of pain, its frequency and the degree of interference in daily living.
At the end of the six-week exercise program, 81 % reported less pain. The duration of the low back pain did not significantly influence the outcome, 80 % of the subjects with pain for two years or less reported improvement, as compared with 82 % of those with pain for as long as 10 to 15 years. Most of the subjects whose trunk muscles improved substantially had improved perceptions about their back pain.
3 5
There are more than a thousand professional instructors conducting back exercise programs in the YMCA organizations throughout the U.S.A. Each course instructor must satisfactorily complete a two-day training workshop covering the theoretical and practical aspects of the program. A medical advisory committee is responsible for the overall direction of the program, "The Y's Way to a Healthy Back.” It determines operating policies, provides direction, monitors research and structures the program to make certain that the highest possible standards of safety are met. This effort represents the largest organized, low-cost approach to dealing with back pain in people who do not require surgery or who have not experienced
satisfactory relief after surgical intervention.
The effect of trunk and quadriceps muscle training on the psychological perception of work and on the subjective assessment of low-back symptoms has been studied in three groups of nursing aides with lumbar spine symptoms. One group took part in the muscle training programme, another group was given a series of informal lectures and a third group served as a control group. Muscle strength increased significantly in the training group compared to the group given lectures, whereas the difference compared to the control group was less pronounced.
Compared to a group of nursing aides without back symptoms, those with lumbar spine symptoms had significantly lower quadriceps muscle strength, whereas their trunk muscle strength was similar. After the study the training group showed a significant positive difference for three of the seven scales used to evaluate the psychological perception of work compared to the group given lectures and the control group. The subjective assessment of low-back symptoms was influenced only as regards the duration of symptoms, which became shorter in the training group compared to the group given lectures, but not compared to the control group. The effect of training on the psychological perception of work seemed to be independent of an increase in muscle strength (Dehlin et al 1978).
