4 Can low back pain disability be prevented? J. W . F R Y M O Y E R
By all accounts the American health care system is in crisis. The issues of costs, accessibility and quality are central to this debate but for many the driving issue is cost. American health care consumes 12.8% of the gross national product, for a current expense of 682 billion dollars. Of greater concern is the trajectory of increase. Because of cost shifting produced by underpayment by federal insurers, annual increases in health care insurance have often exceeded 20%. The result is that more citizens are unable to obtain health insurance coverage; an estimated 37 million people are currently in this plight. A less publicized but equally profound change is occurring in workers' compensation. For the first time, major American insurers are withdrawing from the marketplace of workers' compensation, often involving coverage for major segments of an entire state. The social security administration also is profoundly concerned by its increasing costs, and has instituted stricter eligibility criteria. In other nations, most notably Sweden, a major reappraisal of the social benefits structure is underway, in part driven by the costs of disability which are out of control (A. Nachemson, personal communication). One of the major driving forces behind this change in compensation, social security and social benefits is low back pain disability, which is distinctly a twentieth century (post World War II) phenomenon. Hadler (1991) has concluded that Mixter and Barf's (1934) description of lumbar disc herniation gave credence to the notion that low back pain was commonly the result of injury. Workers' compensation and social entitlement programmes together with a legitimized injury paved the way for the current situation. Following World War II, a virtual explosion occurred in the population of patients who had disability from back pain, both in the United States and Europe. In the last decade a further increase may have occurred as the role of 'chronic repetitive trauma' has become legitimized. The resultant growth rate for low back disability has exceeded all other health conditions. Today there may be as many as 2.5 million Americans with chronic low back disability (DHHS, 1981). Similar trends have been observed in other countries. Although the epidemiological data are scant before World War II, there is little reason to believe this rapid escalation in disability has a basis in new industrial or recreational exposures. Bailli~re' s Clinical Rheumatology--
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The resultant costs, although incompletely understood, are of a staggering order of magnitude. Grazier et al (1984) calculated the direct and indirect costs of low back pain. The direct costs are those related to health care such as diagnostic tests, conservative medical care, operative treatment, hospitalization, etc., while indirect costs refer to work loss, lost productivity and compensation. Grazier et al estimated that the total costs were 14 billion dollars in 1984. A re-analysis of these data calculated that the 1990 costs had risen to at least 50 billion (Cats-Baril and Frymoyer, in press) (see T a b l e 1). Perhaps a m o r e astounding cost was the 11.1 billion dollars ascribed to workers' compensation for low back pain in that same year (Webster and Snook, 1990). Table 1. Estimated direct costs of spinal disorders. From Cats-Baril and Frymoyer (1991a), with permission. Services Hospital inpatient Outpatient and emergency room (ER) Outpatient diagnostic and therapeutic Physician inpatient Physician office, outpatient, and ER Other practitioner Drugs Nursing home Prepayment Non-health sector goods and services Total direct costs
Cost 1984" ($) 4462770000 259 690 000 1010 590 000 1075 750 000 1048120000 233630000 121 340 000 2 933 520 000 501530 000 1275800000 12 922 740 000
Cost 1990t ($) 6780462000 387 980 000 2 000 000 000 1707 080 000 2411690000 2825119000 191 697 000 4 952 394 000 615 080 000 1564651000 23 536153 000
*All figures from Grazier et al, 1984. t Inflated figures from Grazier et al (1984) plus other information (see text). W h a t factor drives these costs? World statistics indicate that 60-80% of all adults have experienced or will experience low back pain (lifetime) incidence (Frymoyer, 1988). Further, low back pain usually has a favourable prognosis for recovery, usually in a matter of days (15-45). The expenses attached to these episodes are usually minimal. The costs in all studies to date relate to a relatively small (5-10%) subset of individuals whose back pain b e c o m e s chronic and is associated with disability. Most economic analyses conclude 70-90% of the total costs (direct and indirect) relate to this small disabled subset (Snook and Jensen, 1984; Spitzer et al, 1987). F r o m the perspective of cost control, it is abundantly clear that the m a j o r focus must be on the prevention of low back disability. Definitions T h e r e are some unimportant differences in the definition of chronic low back pain. The Q u e b e c Study (Spitzer et al, 1987) defined chronic low back pain as continuous symptoms for over 7 weeks, whereas F r y m o y e r and G o r d o n (1989) suggested 12 weeks as an appropriate duration. Disability as used h e r e will m e a n the individual is unable to work (or p e r f o r m w o r k equivalents such as h o m e m a k i n g ) because of the low back symptoms.
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PREVENTION Prevention is usually divided into three categories (Frymoyer and CatsBaril, 1987). Primary prevention attempts to intervene before the individual has ever experienced the symptom. Secondary prevention represents interventions after the symptom has appeared. The goal is to minimize the duration of symptoms and disability, return the individual to full function, and prevent further episodes. Tertiary prevention techniques are those used when the individual has experienced the symptom and has become chronically disabled. Here, the goal is to maximize eventual function through non-medical or surgical rehabilitation, and to return the pe~son to the workplace at the maximal level of possible function. In some instances, this may require modification of the job or workplace.
Primary prevention Primary prevention programmes have evaluated the effects of preemployment evaluation, education and workplace redesign (Chaffin et al, 1978; Cady et al, 1985; Frymoyer and Mooney, 1986; Andersson and Troup, 1991; Chaffin et al, 1991; Nordin et al, 1991). The results have been variable. Pre-employment evaluations historically have included pre-employment physicals and, more recently, analysis of strength. A more sophisticated approach has been to analyse strength and then match the work requirements to the worker's capacity. Many of these strategies have had little impact as measured by prevention of future back pain events (e.g. preemployment radiographs) but continue to be used by some industries as protection against future litigation. Although an abundant literature has amassed in both the scientific and lay press about strength testing, the value of often expensive pre-employment testing remains controversial. In some instances, such as matching strength to job requirements, the evidence strongly suggests benefits (Chaffin et al, 1978). In other instances the results have been paradoxical. Battie (1989) measured the lifting strength of male workers before employment. The long-term surveillance revealed that low back disability was more likely to occur in those whose pre-employment testing showed them to be 'stronger'. Cady et al (1985) similarly analysed physical fitness of fire fighters. Although the more fit had fewer injuries, the cost of their injuries was higher. A plausible interpretation is that the more fit had the more severe, and thus more costly, injuries. Educational programmes have the appeal of being applicable to a large number of workers at low cost. However, such programmes are mainly assessed by comparison of educated workers with historical controls from the same industry. From the strict scientific perspective their value remains speculative. Finally, workplace modification has been promoted by some on the basis of comparative analyses of this strategy and other commonly used methods (education, pre-employment evaluation) (Snook and Jensen, 1984). Some workplace modifications can be simple, for example the placement of
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frequently used heavy tools in more accessible locations; some can be more complex such as lift hoists, tilt carts and vibration dampening devices; and some can involve major retooling, for example, redesigning machinery to minimize the awkward postures commonly assumed by workers as they operate bulky machines. One of the perceived benefits is that workplace modifications require minimum if any compliance. By comparison, to be successful educational programmes require ongoing compliance and memory of the educational 'lesson'.
Secondary prevention In a real sense secondary prevention is a measure of the efficacy of treatment. In the context of this chapter, the measure of efficacy is how soon the worker returns to the job site and then has no further recurrences. The Quebec Study (Spitzer et al, 1987) and other publications (Frymoyer, 1988) have analysed efficacy from this perspective. Although it is not the intent of this chapter to enumerate and analyse critically all possible treatment modalities, it is worth noting that very few treatments have particular efficacy when subjected to this definition. Included in the list are short-term bed rest (as opposed to long-term bed rest) (Deyo, 1986), a few manipulative treatments during acute pain (Haldeman, 1983), structured educational programmes, and selected exercise programmes. Few of these programmes have been subjected to the second measure of efficacy, i.e. the prevention of later episodes. In fact, educational programmes were shown to have no impact on later recurrence (Berquist-Ullman and Larrson, 1977). Two other strategies deserve particular attention. The first is an integrated system of early treatment developed by Nachemson et al (1989). Patients entering that programme had been out of work for 7 weeks and thus, by the Quebec Classification, were already in the early phase of chronic disability. The programme included intensive physical rehabilitation, aerobic reconditioning which in numerous studies has a beneficial effect on connective tissues (Frymoyer and Gordon, 1989), and short-term behavioural modification. Significant reductions in duration of work loss were recorded. The second approach might be termed 'case management' (Wiesel et al, 1984). Efficacy of the intervention was defined by reductions in lost work time, surgical interventions and economic cost compared with historical controls. Striking reductions in all measures were observed. This basis of the approach is close monitoring of the patient by an independent physician, recognized as knowledgeable in low back diagnosis and treatment. In the original study, the independent physician made his evaluations at the worksite. However, this same approach and variations on it have been made by other industries, where the physician is not on-site. A later version has monitored the injured worker's progress by comparing outcomes at multiple intervals following 'injury', comparing multiple parameters of recovery to established diagnostic, treatment, and recovery protocols. Although a true scientific study has not yet been reported, the results parallel those observed in the original cohort (Wiesel et al, 1984).
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Tertiary prevention When a worker becomes disabled, the potential for recovery directly relates to the duration of disability. Historical data indicate that when disability extends one year the potential for gainful employment is 20%, and by two years the potential is minimal. Treatment in those historical studies has been based on a variety of conventional rehabilitative and surgical interventions. In recent studies, comparisons have been made between individuals undergoing conventional treatment versus intensive rehabilitation. In one study (Hazard et al, 1989) the comparison group had an average duration of disability of one year; 20% returned to work, in other words, the prognosis was similar to the historical data. The other study reported a 40% return to work (Mayer et al, 1985) in a cohort whose average duration of disability was also in the range of one year. The reasons for this improved prognosis for untreated workers in the second were not apparent, although the investigators speculated on the possible causes. The treatment programmes used in both studies (Mayer et al, 1985; Hazard et al, 1989) were identical and included careful repetitive quantifications of function, short-term psychological intervention, grade work simulation, and aerobic as well as physical rehabilitation. The outcomes one year following the intervention exceeded 75% in both studies, suggesting substantial efficacy for the programme. Variations of this theme have been analysed with similar or near similar results (J. Weinstein, personal communication). The other major strategy used, whose goal should be tertiary prevention is lumbar spinal surgery. Here the debate is and should be intensive. A few statistics are noteworthy. Overall, the lifetime surgical incidence ranges from 1 to 3% (Deyo et al, 1986). In those with low back disability, the incidence is 10%. One of the final common pathways for these disabled, surgically treated individuals is pain clinics. In one study, 1541 patients were admitted to a centre; of these, 1032 had spinal pain as their admitting diagnosis. Of the 1032 with spinal pain, 826 had undergone one or more unsuccessful operations (Workmens' Compensation Board, 1986). Although there are multiple factors, including selection biases for that particular clinic, the statistics are suggestive. An even more damning conclusion was reached by an analysis of all patients in Oregon who had undergone laminectomy or chymopapain for a low back disorder (Norton, 1986). The striking findings were: (1) common absence of accepted criteria for surgical intervention in the surgically treated patients; (2) low rate of success as measured by return to work; and (3) the high costs attached to failure. Those results mimic those of others (Hanley and Levy, 1989; N. Kahanovitz, personal communication). Indeed, workers' compensation is associated with poorer results even when there is an unequivocal diagnosis of lumbar disc herniation. There is evidence that unequivocal diagnosis is less apt to be forthcoming when chronically disabled patients are analysed (Spengler and Guy, 1990). A counterpoint to this is that failure is the result of the wrong choice of operation based on the wrong diagnosis. Here the lines for debate are drawn around the interpretation of magnetic
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Table 2. Efficacy of prevention strategies for low back pain.
Pre-employment testing Radiographs Strength testing Questionnaires Education Workplace modification Case management Predictive models Quality management
Primary
Secondary
Tertiary
t ? t ?
?t t* t t t ?t ?
?t ? Requiredt ? t ?
* If the goal is to identify workers at risk, the simple question 'Have you been disabled in the past by low back pain?' has predictive value. However, the use of that question to eliminate potential workers from jobs is subject to legal interpretation. t New legislation requires businesses to make 'reasonable accommodations' for individuals with disability.
resonance images and discograms, the efficacy of surgical fusion, and the technique of fusions, such as anterior interbody, circumferential fusion, as well as the benefits of internal fixation. The most objective analysis would conclude that the necessary information is unavailable to prove or refute the efficacy or relative efficacy of such treatments. A summary of these interventions and their efficacy is demonstrated in Table 2. These data indicate that a variety of strategies are applicable to primary, secondary and tertiary prevention. Also, a great deal more analysis is necessary to define fully programmes of the cost-effective efficacy. The more vexing problem is that low back disability continues to rise, despite more diagnosis, more treatment, more work hardening, more rehabilitation, and more pain clinics. This has led students of the field of low back pain and disability in general to conclude that the problem is not medical but societal (Biering-Sorensen, 1984; Waddell et al, 1984; Waddell, 1987, 1990; Hadler, 1991). Some of the important factors are psychological dysfunction (Mixter and Barr, 1934; Deyo and Diehl, 1983; Roland and Morris, 1983; Cairns et al, 1984), adverse work environments (Hanley and Levy, 1989), difficulties of workers in relating to peers and supervisors (Battie, 1989; Bigos and Battie, 1991), demographic factors such as low income and lower level of education (Cats-Baril and Frymoyer, 1991a, in press), and the presence of legal counsel, i.e. the perception of compensable fault (Haddad, 1987). Many of these factors are shared with the broader societal issues about American workers voiced in the lay press, television commentaries, and most recently, in the negative comparison of the American worker with the Japanese counterpart. These same factors have led some analysts such as Hadler (1991) and Waddell (1987) to conclude that the traditional biological model is not applicable to the majority of patients with low back disability. Waddell attempted a determination of the contribution of physical and psychological distress and illness behaviour to low back disability, which according to his analysis were 40% and 31% respectively.
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P R E D I C T I O N OF DISABILITY
During the past 7 years our laboratory has attempted to analyse the multiple factors associated with disability. We have asked the question, 'Can low back disability be predicted early in the course of the patient's symptoms'? The corollary hypothesis has been: 'If low back pain disability can be predicted then early aggressive rehabilitation should be preventive and cost effective'. The details of this study design and some of its limitations have been reported elsewhere (Cats-Baril and Frymoyer, 1991b). The general approach has been to analyse from the literature all the factors thought to predict disability. Through a group interactive process involving a panel of experts, the multiple factors thought to be predictive have been weighted and ranked. These data are shown in Table 3. Test questions were
Table 3. Possible predictive factors for low back pain disability. Cats-B aril and Frymoyer (1991b), with permission. Organic
Nonorganic
Diagnosis Sciatica Acute treatment Operative intervention Muscle strength, endurance Aerobic capacity Age, gender Psychologic profile Illness behaviour Work environment Compensation and perception of injury Attorneys Duration of disability Education, income
developed to measure these factors, first in a computer-assisted model. Following preliminary analysis, less predictive variables were eliminated and eventually a pencil and paper version was derived. Data were analysed using the 'panel of experts' analyses to derive a predictive model. The data were then re-evaluated using a logistic regression model, to recalculate the weights of the various factors, the so-called 'empiric model'. Sensitivity, specificity and predictive, values were calculated. The overall predictive value of the test was 89% where the outcome measure was whether the patient is working or not working 6 months and one year later. In publication of these data, we urged caution, primarily because the sample included patients who had been disabled for as long as 3 months. As might be expected the duration of disability was the single most predictive factor. (If the recovery curve for low back pain (Haldeman, 1983) is analysed, it will be observed that with each passing week, the probability of disability significantly increases, even during the first 3 months.)
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The factors which predicted disability in this model are shown in Table 4. Note that the majority of factors relate to 'non-organic' factors, which tends to confirm but not prove much of the data regarding low back disability. The second hypothesis raised by this study, 'Will early intervention prevent future disability and be cost effective?' has yet to be studied. However, the Gothenberg studies (Nachemson et al, 1989) suggest strongly that early aggressive intervention is effective. More importantly, the early aggressive intervention they used is simply a restructuring and systematic use of lowcost treatments.
Table 4. Weights assigned to factors by the panel of experts. From Cats-Baril and Frymoyer (1991a), with permission. Factor
Job factors (total) Physical requirements of job Occupation Job satisfaction Self-employment Work history Employer's attitude towards limited duty Preference: Disability/work/retiring
Psychosocial factors (total) Psychological symptoms Self-efficacy Personality type Daily hassles
Injury factors (total) Compensability Perception of fault Lawyer involvement
Diagnostic factors (total) Pain Presence or absence of sciatica Physical findings
Demographic factors (total) Education
Age Household income Marital status Child-care responsibility
Medical history factors (total) Disability history Past hospitalizations
Health behaviours factors (total) Alcohol use Smoking Drug familiarity
Anthropometricfactors (total) Fitness level
Weight 20.1 5.5 3.3 2.8 2.8 2.8 2.2 .7 20.0 8.6 5.0 3.4 3.0 18.5 8.2 5.4 4.9 15.4 4.5 3.6 7.3 8.2 3.1 2.4 1.5 .9 .3 7.9 5.6 2.3 5.4 2.5 2.4 .5 4.5 4.5
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Table 5. Significant factors in predicting low back pain disability. From Cats-Baril and Frymoyer (1991a), with permission.
Injury Perception of fault PerCeption of compensability Lawyer involvement
Self-Efficacy Patient's prediction of continued disability
Demographics Household income Education
Pain History Has patient been back at work while suffering pain Duration of pain
Job Job satisfaction Employer's attitude toward limited duty Physical requirements
CONCLUSION The question posed by this chapter is: 'Can low back disability be prevented?' The conclusion is a guarded, 'Yes'. At each level of prevention (primary, secondary and tertiary), there appear to be effective strategies. Precisely how effective and at what cost remains an issue for continued scientific study. The more vexing issue is raised by the information and analyses which strongly suggest that disability is part of a larger societal problem. The solution to the problem ultimately may not be solvable by health professionals. Public policy bodies are addressing this issue through revision of social security eligibility criteria in the United States, and redefinitions of policies and benefits in Sweden. Market forces will also dictate change. Compensation carriers moving from large markets, and the new more costly alternatives, are already leading employers to reappraise their policies and state governments to address the workers' compensation law. One possible optimistic solution is new systems of employer-employee relationships embodied in 'Total Quality Management' or TQM for short. Amongst its many attributes, TQM seeks to 'empower' workers; the goal is for workers to identify themselves with solutions. The cynical perspective is that the battle will be joined by coalitions representing unions, civil libertarians and politicians. Although low back pain disability is not the only issue, it clearly is a substantial part of the problem as measured by economic impact and thus will be a natural focus.
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REFERENCES
Andersson GBJ & Troup JDG (1991) Worker selection. In Pope MH, Andersson GBJ, Frymoyer JW & Chaffin DB (eds) Occupational Low Back Pain, pp 239-250. St Louis: Mosby Year Book. Battie MD (1989) The reliability of physical factors as predictors of the occurrence of back pain reports: a prospective study within industry. Doctoral Thesis. Goteborg University. Berquist-UUman M & Larrson U (1977) Acute low back pain in industry: a controlled prospective study with special reference to therapy and confounding factors. Acta Orthopaedica Scandinavica 170 (supplement): 1. Biering-Sorensen F (1984) A one-year prospective study of low back pain in the general population: the prognostic value of low back history and physical measurements. Danish Medical Bulletin 31: 362. Bigos SJ & Battie MC (1991) The impact of spinal disorders in industry. In Frymoyer JW (ed.) The Adult Spine, Principles and Practice, pp 145--154. New York: Raven Press. Cady LD Jr, Thomas PC & Karwasky RJ (1985) Program for increasing health and physical fitness of fire fighters. Journal of Occupational Medicine 27: 110. Cairns D, Mooney V & Crane P (1984) Spinal pain rehabilitation: inpatient and outpatient treatment results and development of predictors for outcome. Spine 9: 91. Cats-Baril WL & Frymoyer JW (1991a) The economics of spinal disorders. In Frymoyer JW (ed.) The Adult Spine, Principles and Practice, pp 85-106. New York: Raven Press. Cats-Baril WL & Frymoyer JW (1991b) Identifying patients at risk of becoming disabled due to low back pain: the Vermont Rehabilitation Engineering Center predictive model. Spine 16: 605. Cats-Baril WL & Frymoyer JW (1992) Demographic factors associated with the prevalence of disability in the general population: analysis of the NHANES f database. Spine (in press). Chaffin DB, Herrin BD & Keyserling WM (1978) Preemployment strength testing: an updated position. Journal of Occupational Medicine 20: 403. Chaffin DB, Pope MH & Andersson GBJ (1991) Workplace design. In Pope, MH, Andersson GBJ, Frymoyer JW & Chaffin DB (eds) Occupational Low Back Pain, pp 251-265. St Louis: Mosby Yearbook. Deyo R A & Diehl AK (1983) Measuring physical and psychosocial function of patients with low back pain. Spine 8: 635. Deyo RA, Diehl AK & Rosenthal M (1986) How many days of bed rest for acute low back pain? A randomized clinical trial. New England Journal of Medicine 315: 1064. DHHS (1981). Prevalence of Selected Impairment, United States 1977. Hyattsville, MD: National Center for Health Statistics (DHHS publication (PHS) Series 10, No 134). Frymoyer JW (1988) Back pain and sciatica. New England Journal of Medicine 318: 291. Frymoyer JW & Cats-Baril (1987) Predictors of low back pain disability. Clinical Orthopaedics 221: 89. Frymoyer JW & Gordon SL (eds) (1989) New Perspectives in Low Back Pain. Chicago: American Academy of Orthopaedic Surgeons. Frymoyer JW & Mooney V (1986) Current concepts review, Occupational Orthopaedics. Journal of Bone and Joint Surgery 68A; 469. Frymoyer JW, Rosen JC, Clements J & Pope MH (1985) Psychologic factors in low-back pain disability. Clinical Orthopaedics 195: 178. Grazier KL, Holbrook TL, Kelsey JL & Stouffer RN (eds) (1984)The Frequency of Occurrence, Impact, and Cost of Musculoskeletal Conditions in the United States. Chicago: American Academy of Orthopaedic Surgeons. Haddad GH (1987) Analysis of 2932 workers' compensation back injury cases. The impact on the cost to the system. Spine 12: 765. Hadler NM (1991) Backache and humanism. In Frymoyer JW (ed.) The Adult Spine, Principles and Practice, pp 55-60. New York: Raven Press. Hakelius A (1970) Prognosis in sciatica: a clinical follow-up of surgical and non-surgical treatment. Acta Orthopaedica Scandinavica 129 (supplement): 1. Haldeman S (1983) Spinal manipulative therapy: a status report. ClinicalOrthopaedics 179: 62. Hanley EH & Levy JA (1989) Surgical treatment of isthmic spondylolisthesis: analysis of variables influencing results. Spine 14: 48.
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Hazard GG, Fenwick JW, Kalisch SM et al (1989) Functional restoration with behavioral support: a one-year prospective study of patients with chronic low back pain. Spine 14: 157. Hendler N, Mollett A, Talo S & Levin S (1989) A comparison between the Minnesota Multiphasic Personality Inventory and the Mensana Clinic Back Pain Test for validating the complaint of chronic low back pain. Journal of Occupational Medicine 30" 98. Herron L, Turner J & Weiner P (1988) Does the MMPI predict chemonucleolysis outcome? Spine 13: 84. Mayer TG, Gatchel R J, Koshino ? et al (1985) Objective assessment of spine function following industrial injury: a prospective study with comparison group and one-year follow-up. Spine 10: 482. Million R, Hall W, Nilsen KH et al (1982) Assessment of the progress of the back pain patient: 198l Volvo Award in Clinical Science. Spine 7: 204. Mixter WJ & Barr JS (1934) Rupture of the intervertebral disc with involvement of the spinal canal. New England Journal of Medicine 211: 210. Nachemson AL, Eek C, Lindstrom Iet al (1989) Chronic low back pain disability can largely be prevented: a prospective randomized trial in industry. Presented at the 56th Annual Meeting of the American Academy of Orthopaedic Surgeons, Las Vegas, Nevada, Feb. 9-14, 1989. Nordin M, Battie M, Pope MH & Snook S (1991) Education and training, in Pope MH, Andersson GBJ, Frymoyer JW & Chaffin D (eds) Occupational Low Back Pain, pp 266278. St Louis: Mosby Yearbook. Norton WL (1986) Chemonucleolysis versus surgical diskectomy: comparison of costs and results in workers' compensation claimants. Spine 11: 440. Ransford AO, Cairns D & Mooney V (1976) The pain drawing as an aid to the psychologic evaluation of patients with low back pain. Spine 1: 127. Roland M & Morris R (1983) A study of the natural history of back pain. Part I. Development of reliable and sensitive measure of disability in low back pain. Spine 8: 141. Schneider PL & Kahnovitz N (1990) Clinical testing in chronic low back pain. Surg. Rounds Orthop. 4: 19. Snook SH & Jensen RC (1984) Cost. In Pose MH, Frymoyer JW & Andersson G (eds) Occupational Low Back Pain. New York: Praeger. Sorensen LV & Mors O (1988) Presentation of a new MMPI scale to predict outcome after first lumbar diskectomy. Pain 34: 191. Spengler DM & Guy DP (1990) Industrial low back pain: a practical approach. In Weinstein JN & Wiesel SW (eds) The Lumbar Spine. Philadelphia: W.B. Saunders. Spengler DM, Freeman C, Westbrook R & Miller JW (1980) Low back pain following multiple lumbar spine procedures: failure of initial selections. Spine 4: 356. Spitzer WO, LeBlanc FE, Dupuis M e t al (1987) Scientific approach to the assessment and management of activity-related spinal disorders: a monograph for clinicians. Report of the Quebec Task Force on Spinal Disorders. Spine 12: 1. Svensson HO & Andersson GBJ (1983) Low back pain in 40 to 47 year-old men: work history and work environment factors. Spine i: 272. Troup JDG, Martin JW & Lloyd DCEF (1981) Back pain in industry: a prospective survey. Spine 6: 61. Vallfors B (1985) Acute, subacute and chronic low back pain: clinical symptoms, absenteeism, and working environment. Scandinavian Journal of Rehabilitation Medicine 1 (supplement): 1. Waddell G (1987) Clinical assessment of lumbar impairment. Clinical Orthopaedics 221: 110. Waddell G (1990) A new clinical model for the treatment of low back pain. In Weinstein JN & Wiesel SW (eds) The Lumbar Spine, pp 38-56. Philadelphia: W.B. Saunders. Waddell G, McCulloch JA, Kummel E & Wenner RM (1980) Nonorganic physical signs in low back pain. Spine 5: 117. Waddell G, Main CA, Morris EW et al (1984) Chronic low back pain, psychologic distress and illness behaviour. Spine 9: 209. Weber H (1983) Lumbar disc herniation: a controlled prospective study with ten years of observation. Spine 8: 131. Webster BS & Snook SH (1990) The cost of compensatable low back pain. Journal of Occupational Medicine 32: 13.
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Wiesel SW, Feffer H L & Rothman RH (1984) Industrial low back pain: a prospective evaluation of a standardized diagnostic and treatment protocol. Spine 9: 199. Workmens' Compensation Board (1986) Symposium on Low Back Pain: A multidisciplinary approach. Vancouver, Canada.,
By all accounts the American health care system is in crisis. The issues of costs, accessibility and quality are central to this debate but for many the driving issue is cost. American health care consumes 12.8% of the gross national product, for a current expense of 682 billion dollars. Of greater concern is the trajectory of increase. Because of cost shifting produced by underpayment by federal insurers, annual increases in health care insurance have often exceeded 20%. The result is that more citizens are unable to obtain health insurance coverage; an estimated 37 million people are currently in this plight. A less publicized but equally profound change is occurring in workers' compensation. For the first time, major American insurers are withdrawing from the marketplace of workers' compensation, often involving coverage for major segments of an entire state. The social security administration also is profoundly concerned by its increasing costs, and has instituted stricter eligibility criteria. In other nations, most notably Sweden, a major reappraisal of the social benefits structure is underway, in part driven by the costs of disability which are out of control (A. Nachemson, personal communication). One of the major driving forces behind this change in compensation, social security and social benefits is low back pain disability, which is distinctly a twentieth century (post World War II) phenomenon. Hadler (1991) has concluded that Mixter and Barf's (1934) description of lumbar disc herniation gave credence to the notion that low back pain was commonly the result of injury. Workers' compensation and social entitlement programmes together with a legitimized injury paved the way for the current situation. Following World War II, a virtual explosion occurred in the population of patients who had disability from back pain, both in the United States and Europe. In the last decade a further increase may have occurred as the role of 'chronic repetitive trauma' has become legitimized. The resultant growth rate for low back disability has exceeded all other health conditions. Today there may be as many as 2.5 million Americans with chronic low back disability (DHHS, 1981). Similar trends have been observed in other countries. Although the epidemiological data are scant before World War II, there is little reason to believe this rapid escalation in disability has a basis in new industrial or recreational exposures. Bailli~re' s Clinical Rheumatology--
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The resultant costs, although incompletely understood, are of a staggering order of magnitude. Grazier et al (1984) calculated the direct and indirect costs of low back pain. The direct costs are those related to health care such as diagnostic tests, conservative medical care, operative treatment, hospitalization, etc., while indirect costs refer to work loss, lost productivity and compensation. Grazier et al estimated that the total costs were 14 billion dollars in 1984. A re-analysis of these data calculated that the 1990 costs had risen to at least 50 billion (Cats-Baril and Frymoyer, in press) (see T a b l e 1). Perhaps a m o r e astounding cost was the 11.1 billion dollars ascribed to workers' compensation for low back pain in that same year (Webster and Snook, 1990). Table 1. Estimated direct costs of spinal disorders. From Cats-Baril and Frymoyer (1991a), with permission. Services Hospital inpatient Outpatient and emergency room (ER) Outpatient diagnostic and therapeutic Physician inpatient Physician office, outpatient, and ER Other practitioner Drugs Nursing home Prepayment Non-health sector goods and services Total direct costs
Cost 1984" ($) 4462770000 259 690 000 1010 590 000 1075 750 000 1048120000 233630000 121 340 000 2 933 520 000 501530 000 1275800000 12 922 740 000
Cost 1990t ($) 6780462000 387 980 000 2 000 000 000 1707 080 000 2411690000 2825119000 191 697 000 4 952 394 000 615 080 000 1564651000 23 536153 000
*All figures from Grazier et al, 1984. t Inflated figures from Grazier et al (1984) plus other information (see text). W h a t factor drives these costs? World statistics indicate that 60-80% of all adults have experienced or will experience low back pain (lifetime) incidence (Frymoyer, 1988). Further, low back pain usually has a favourable prognosis for recovery, usually in a matter of days (15-45). The expenses attached to these episodes are usually minimal. The costs in all studies to date relate to a relatively small (5-10%) subset of individuals whose back pain b e c o m e s chronic and is associated with disability. Most economic analyses conclude 70-90% of the total costs (direct and indirect) relate to this small disabled subset (Snook and Jensen, 1984; Spitzer et al, 1987). F r o m the perspective of cost control, it is abundantly clear that the m a j o r focus must be on the prevention of low back disability. Definitions T h e r e are some unimportant differences in the definition of chronic low back pain. The Q u e b e c Study (Spitzer et al, 1987) defined chronic low back pain as continuous symptoms for over 7 weeks, whereas F r y m o y e r and G o r d o n (1989) suggested 12 weeks as an appropriate duration. Disability as used h e r e will m e a n the individual is unable to work (or p e r f o r m w o r k equivalents such as h o m e m a k i n g ) because of the low back symptoms.
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PREVENTION Prevention is usually divided into three categories (Frymoyer and CatsBaril, 1987). Primary prevention attempts to intervene before the individual has ever experienced the symptom. Secondary prevention represents interventions after the symptom has appeared. The goal is to minimize the duration of symptoms and disability, return the individual to full function, and prevent further episodes. Tertiary prevention techniques are those used when the individual has experienced the symptom and has become chronically disabled. Here, the goal is to maximize eventual function through non-medical or surgical rehabilitation, and to return the pe~son to the workplace at the maximal level of possible function. In some instances, this may require modification of the job or workplace.
Primary prevention Primary prevention programmes have evaluated the effects of preemployment evaluation, education and workplace redesign (Chaffin et al, 1978; Cady et al, 1985; Frymoyer and Mooney, 1986; Andersson and Troup, 1991; Chaffin et al, 1991; Nordin et al, 1991). The results have been variable. Pre-employment evaluations historically have included pre-employment physicals and, more recently, analysis of strength. A more sophisticated approach has been to analyse strength and then match the work requirements to the worker's capacity. Many of these strategies have had little impact as measured by prevention of future back pain events (e.g. preemployment radiographs) but continue to be used by some industries as protection against future litigation. Although an abundant literature has amassed in both the scientific and lay press about strength testing, the value of often expensive pre-employment testing remains controversial. In some instances, such as matching strength to job requirements, the evidence strongly suggests benefits (Chaffin et al, 1978). In other instances the results have been paradoxical. Battie (1989) measured the lifting strength of male workers before employment. The long-term surveillance revealed that low back disability was more likely to occur in those whose pre-employment testing showed them to be 'stronger'. Cady et al (1985) similarly analysed physical fitness of fire fighters. Although the more fit had fewer injuries, the cost of their injuries was higher. A plausible interpretation is that the more fit had the more severe, and thus more costly, injuries. Educational programmes have the appeal of being applicable to a large number of workers at low cost. However, such programmes are mainly assessed by comparison of educated workers with historical controls from the same industry. From the strict scientific perspective their value remains speculative. Finally, workplace modification has been promoted by some on the basis of comparative analyses of this strategy and other commonly used methods (education, pre-employment evaluation) (Snook and Jensen, 1984). Some workplace modifications can be simple, for example the placement of
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frequently used heavy tools in more accessible locations; some can be more complex such as lift hoists, tilt carts and vibration dampening devices; and some can involve major retooling, for example, redesigning machinery to minimize the awkward postures commonly assumed by workers as they operate bulky machines. One of the perceived benefits is that workplace modifications require minimum if any compliance. By comparison, to be successful educational programmes require ongoing compliance and memory of the educational 'lesson'.
Secondary prevention In a real sense secondary prevention is a measure of the efficacy of treatment. In the context of this chapter, the measure of efficacy is how soon the worker returns to the job site and then has no further recurrences. The Quebec Study (Spitzer et al, 1987) and other publications (Frymoyer, 1988) have analysed efficacy from this perspective. Although it is not the intent of this chapter to enumerate and analyse critically all possible treatment modalities, it is worth noting that very few treatments have particular efficacy when subjected to this definition. Included in the list are short-term bed rest (as opposed to long-term bed rest) (Deyo, 1986), a few manipulative treatments during acute pain (Haldeman, 1983), structured educational programmes, and selected exercise programmes. Few of these programmes have been subjected to the second measure of efficacy, i.e. the prevention of later episodes. In fact, educational programmes were shown to have no impact on later recurrence (Berquist-Ullman and Larrson, 1977). Two other strategies deserve particular attention. The first is an integrated system of early treatment developed by Nachemson et al (1989). Patients entering that programme had been out of work for 7 weeks and thus, by the Quebec Classification, were already in the early phase of chronic disability. The programme included intensive physical rehabilitation, aerobic reconditioning which in numerous studies has a beneficial effect on connective tissues (Frymoyer and Gordon, 1989), and short-term behavioural modification. Significant reductions in duration of work loss were recorded. The second approach might be termed 'case management' (Wiesel et al, 1984). Efficacy of the intervention was defined by reductions in lost work time, surgical interventions and economic cost compared with historical controls. Striking reductions in all measures were observed. This basis of the approach is close monitoring of the patient by an independent physician, recognized as knowledgeable in low back diagnosis and treatment. In the original study, the independent physician made his evaluations at the worksite. However, this same approach and variations on it have been made by other industries, where the physician is not on-site. A later version has monitored the injured worker's progress by comparing outcomes at multiple intervals following 'injury', comparing multiple parameters of recovery to established diagnostic, treatment, and recovery protocols. Although a true scientific study has not yet been reported, the results parallel those observed in the original cohort (Wiesel et al, 1984).
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Tertiary prevention When a worker becomes disabled, the potential for recovery directly relates to the duration of disability. Historical data indicate that when disability extends one year the potential for gainful employment is 20%, and by two years the potential is minimal. Treatment in those historical studies has been based on a variety of conventional rehabilitative and surgical interventions. In recent studies, comparisons have been made between individuals undergoing conventional treatment versus intensive rehabilitation. In one study (Hazard et al, 1989) the comparison group had an average duration of disability of one year; 20% returned to work, in other words, the prognosis was similar to the historical data. The other study reported a 40% return to work (Mayer et al, 1985) in a cohort whose average duration of disability was also in the range of one year. The reasons for this improved prognosis for untreated workers in the second were not apparent, although the investigators speculated on the possible causes. The treatment programmes used in both studies (Mayer et al, 1985; Hazard et al, 1989) were identical and included careful repetitive quantifications of function, short-term psychological intervention, grade work simulation, and aerobic as well as physical rehabilitation. The outcomes one year following the intervention exceeded 75% in both studies, suggesting substantial efficacy for the programme. Variations of this theme have been analysed with similar or near similar results (J. Weinstein, personal communication). The other major strategy used, whose goal should be tertiary prevention is lumbar spinal surgery. Here the debate is and should be intensive. A few statistics are noteworthy. Overall, the lifetime surgical incidence ranges from 1 to 3% (Deyo et al, 1986). In those with low back disability, the incidence is 10%. One of the final common pathways for these disabled, surgically treated individuals is pain clinics. In one study, 1541 patients were admitted to a centre; of these, 1032 had spinal pain as their admitting diagnosis. Of the 1032 with spinal pain, 826 had undergone one or more unsuccessful operations (Workmens' Compensation Board, 1986). Although there are multiple factors, including selection biases for that particular clinic, the statistics are suggestive. An even more damning conclusion was reached by an analysis of all patients in Oregon who had undergone laminectomy or chymopapain for a low back disorder (Norton, 1986). The striking findings were: (1) common absence of accepted criteria for surgical intervention in the surgically treated patients; (2) low rate of success as measured by return to work; and (3) the high costs attached to failure. Those results mimic those of others (Hanley and Levy, 1989; N. Kahanovitz, personal communication). Indeed, workers' compensation is associated with poorer results even when there is an unequivocal diagnosis of lumbar disc herniation. There is evidence that unequivocal diagnosis is less apt to be forthcoming when chronically disabled patients are analysed (Spengler and Guy, 1990). A counterpoint to this is that failure is the result of the wrong choice of operation based on the wrong diagnosis. Here the lines for debate are drawn around the interpretation of magnetic
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Table 2. Efficacy of prevention strategies for low back pain.
Pre-employment testing Radiographs Strength testing Questionnaires Education Workplace modification Case management Predictive models Quality management
Primary
Secondary
Tertiary
t ? t ?
?t t* t t t ?t ?
?t ? Requiredt ? t ?
* If the goal is to identify workers at risk, the simple question 'Have you been disabled in the past by low back pain?' has predictive value. However, the use of that question to eliminate potential workers from jobs is subject to legal interpretation. t New legislation requires businesses to make 'reasonable accommodations' for individuals with disability.
resonance images and discograms, the efficacy of surgical fusion, and the technique of fusions, such as anterior interbody, circumferential fusion, as well as the benefits of internal fixation. The most objective analysis would conclude that the necessary information is unavailable to prove or refute the efficacy or relative efficacy of such treatments. A summary of these interventions and their efficacy is demonstrated in Table 2. These data indicate that a variety of strategies are applicable to primary, secondary and tertiary prevention. Also, a great deal more analysis is necessary to define fully programmes of the cost-effective efficacy. The more vexing problem is that low back disability continues to rise, despite more diagnosis, more treatment, more work hardening, more rehabilitation, and more pain clinics. This has led students of the field of low back pain and disability in general to conclude that the problem is not medical but societal (Biering-Sorensen, 1984; Waddell et al, 1984; Waddell, 1987, 1990; Hadler, 1991). Some of the important factors are psychological dysfunction (Mixter and Barr, 1934; Deyo and Diehl, 1983; Roland and Morris, 1983; Cairns et al, 1984), adverse work environments (Hanley and Levy, 1989), difficulties of workers in relating to peers and supervisors (Battie, 1989; Bigos and Battie, 1991), demographic factors such as low income and lower level of education (Cats-Baril and Frymoyer, 1991a, in press), and the presence of legal counsel, i.e. the perception of compensable fault (Haddad, 1987). Many of these factors are shared with the broader societal issues about American workers voiced in the lay press, television commentaries, and most recently, in the negative comparison of the American worker with the Japanese counterpart. These same factors have led some analysts such as Hadler (1991) and Waddell (1987) to conclude that the traditional biological model is not applicable to the majority of patients with low back disability. Waddell attempted a determination of the contribution of physical and psychological distress and illness behaviour to low back disability, which according to his analysis were 40% and 31% respectively.
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P R E D I C T I O N OF DISABILITY
During the past 7 years our laboratory has attempted to analyse the multiple factors associated with disability. We have asked the question, 'Can low back disability be predicted early in the course of the patient's symptoms'? The corollary hypothesis has been: 'If low back pain disability can be predicted then early aggressive rehabilitation should be preventive and cost effective'. The details of this study design and some of its limitations have been reported elsewhere (Cats-Baril and Frymoyer, 1991b). The general approach has been to analyse from the literature all the factors thought to predict disability. Through a group interactive process involving a panel of experts, the multiple factors thought to be predictive have been weighted and ranked. These data are shown in Table 3. Test questions were
Table 3. Possible predictive factors for low back pain disability. Cats-B aril and Frymoyer (1991b), with permission. Organic
Nonorganic
Diagnosis Sciatica Acute treatment Operative intervention Muscle strength, endurance Aerobic capacity Age, gender Psychologic profile Illness behaviour Work environment Compensation and perception of injury Attorneys Duration of disability Education, income
developed to measure these factors, first in a computer-assisted model. Following preliminary analysis, less predictive variables were eliminated and eventually a pencil and paper version was derived. Data were analysed using the 'panel of experts' analyses to derive a predictive model. The data were then re-evaluated using a logistic regression model, to recalculate the weights of the various factors, the so-called 'empiric model'. Sensitivity, specificity and predictive, values were calculated. The overall predictive value of the test was 89% where the outcome measure was whether the patient is working or not working 6 months and one year later. In publication of these data, we urged caution, primarily because the sample included patients who had been disabled for as long as 3 months. As might be expected the duration of disability was the single most predictive factor. (If the recovery curve for low back pain (Haldeman, 1983) is analysed, it will be observed that with each passing week, the probability of disability significantly increases, even during the first 3 months.)
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The factors which predicted disability in this model are shown in Table 4. Note that the majority of factors relate to 'non-organic' factors, which tends to confirm but not prove much of the data regarding low back disability. The second hypothesis raised by this study, 'Will early intervention prevent future disability and be cost effective?' has yet to be studied. However, the Gothenberg studies (Nachemson et al, 1989) suggest strongly that early aggressive intervention is effective. More importantly, the early aggressive intervention they used is simply a restructuring and systematic use of lowcost treatments.
Table 4. Weights assigned to factors by the panel of experts. From Cats-Baril and Frymoyer (1991a), with permission. Factor
Job factors (total) Physical requirements of job Occupation Job satisfaction Self-employment Work history Employer's attitude towards limited duty Preference: Disability/work/retiring
Psychosocial factors (total) Psychological symptoms Self-efficacy Personality type Daily hassles
Injury factors (total) Compensability Perception of fault Lawyer involvement
Diagnostic factors (total) Pain Presence or absence of sciatica Physical findings
Demographic factors (total) Education
Age Household income Marital status Child-care responsibility
Medical history factors (total) Disability history Past hospitalizations
Health behaviours factors (total) Alcohol use Smoking Drug familiarity
Anthropometricfactors (total) Fitness level
Weight 20.1 5.5 3.3 2.8 2.8 2.8 2.2 .7 20.0 8.6 5.0 3.4 3.0 18.5 8.2 5.4 4.9 15.4 4.5 3.6 7.3 8.2 3.1 2.4 1.5 .9 .3 7.9 5.6 2.3 5.4 2.5 2.4 .5 4.5 4.5
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Table 5. Significant factors in predicting low back pain disability. From Cats-Baril and Frymoyer (1991a), with permission.
Injury Perception of fault PerCeption of compensability Lawyer involvement
Self-Efficacy Patient's prediction of continued disability
Demographics Household income Education
Pain History Has patient been back at work while suffering pain Duration of pain
Job Job satisfaction Employer's attitude toward limited duty Physical requirements
CONCLUSION The question posed by this chapter is: 'Can low back disability be prevented?' The conclusion is a guarded, 'Yes'. At each level of prevention (primary, secondary and tertiary), there appear to be effective strategies. Precisely how effective and at what cost remains an issue for continued scientific study. The more vexing issue is raised by the information and analyses which strongly suggest that disability is part of a larger societal problem. The solution to the problem ultimately may not be solvable by health professionals. Public policy bodies are addressing this issue through revision of social security eligibility criteria in the United States, and redefinitions of policies and benefits in Sweden. Market forces will also dictate change. Compensation carriers moving from large markets, and the new more costly alternatives, are already leading employers to reappraise their policies and state governments to address the workers' compensation law. One possible optimistic solution is new systems of employer-employee relationships embodied in 'Total Quality Management' or TQM for short. Amongst its many attributes, TQM seeks to 'empower' workers; the goal is for workers to identify themselves with solutions. The cynical perspective is that the battle will be joined by coalitions representing unions, civil libertarians and politicians. Although low back pain disability is not the only issue, it clearly is a substantial part of the problem as measured by economic impact and thus will be a natural focus.
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