The following letter is published as a response to the article, “Repetitive Stress Injury: Diagnosis or Self-Fulfilling Prophecy?” (82-A: 1314-1322, Sept. 2000), by Szabo and King.
To The Editor:
I am
writing with regard to the Current Concepts Review entitled “Repetitive Stress
Injury: Diagnosis or Self-Fulfilling Prophecy?” (82-A: 1314-1322, Sept. 2000),
by Szabo and King. The authors of the article review a specific legal case of
keyboard use as a cause of repetitive stress injury (RSI) and also discuss the
topic of overuse injuries in the workplace in general. It is undoubtedly true
that the evidence associating keyboard use with specific injuries is weak, that
the benefit of ergonomically motivated changes in keyboard design is unknown,
and that the use of the term RSI as a specific diagnosis is ill-advised. However,
in generalizing from a specific case of keyboard use as a cause of a specific
entity called RSI to the larger issues of repetitive activity as a cause of injury
in the workplace and the role of ergonomics in understanding and reducing such
injuries, Szabo and King move from firm to far shakier ground.
First, they greatly overstate the magnitude and locus of the problem, possibly because they use outdated data. The data that they cite are from 1992 and were obtained from Bureau of Labor Statistics (BLS) reports. These annual reports track all work-related musculoskeletal disorders (WRMSDs), from fractures and lacerations to the dreaded RSI. The most recent data are from 1998. According to these reports, both the rate and the absolute number of WRMSDs peaked in 1993 and have been diminishing, in all categories, ever since1. The number of cases of carpal tunnel syndrome (CTS) resulting in lost work days, for example, has dropped by more than 30%, to roughly 26,000 in 1998, for a rate of three per 10,000 workers1. The rate of such cases in which repetitive motion was implicated has likewise decreased, to 7.4 per 10,000 workers (less than 5% of all WRMSDs reported in the 1998 BLS data)1. Acute transient injury such as back strain was the most common category of WRMSD, representing more than one-half of the total, followed by injuries due to falls, injuries due to machinery, fractures, and lacerations. Furthermore, clerical workers had few WRMSDs of any sort; the most common occupations cited in the BLS list were truck drivers, laborers, and hospital orderlies, with secretaries ranked last at forty-third. Thus, rather than “an epidemic of so-called work-related musculoskeletal problems,” the BLS data demonstrate a moderate and steadily diminishing number of cases, concentrated in just the sorts of jobs that one would expect: occupations requiring heavy lifting, gripping, and high-force/high-repetition work, which often are associated with awkward postures as well. One can only speculate with regard to the reason for the decrease in reported work-related musculoskeletal problems, but ergonomic improvements in the workplace seem to be a logical candidate, as will be discussed below. Other explanations are unlikely. The decrease began long before the keyboard cases received broad public attention, and the decline did not coincide with a change in the legal status of certain WRMSDs, as occurred in Australia.
The second issue relates to the documentation--or rather the lack of it, as no references are cited--for the strong statements that ergonomists have recommended legislation “on the basis of the unproved claim that work-related musculoskeletal disorders are disabling physical conditions” and that “they have not lowered the prevalence of these disorders.” As noted in the recent report by the Steering Committee of the National Academy of Sciences (NAS) Workshop on Work-Related Musculoskeletal Disorders, “one feature of the discourse around musculoskeletal disorders is that it sometimes involves individuals from one discipline (or subdiscipline) who reject entirely the legitimacy of research from another.”2 Perhaps it was unintended, but the use of strongly worded, undocumented statements such as those above and headings such as “Ergonomics Unchained” suggest at least the possibility that Szabo and King are questioning the legitimacy of ergonomics as a scientific discipline. If so, this is unjust. The data cited above clearly show that the prevalence of WRMSDs has gone down, and, as the BLS definition of WRMSDs includes fractures, lacerations, carpal tunnel syndrome, and a variety of other specific conditions, perhaps we can agree that at least some WRMSDs are disabling. But we can also use sources cited by Szabo and King, provided that we are willing to read a bit further in the sources themselves. For example, they refer to the “stark observations” of the NAS report, which raises questions regarding the quality of the data supporting repetition as an etiology of musculoskeletal injury. The four bulleted items quoted by Szabo and King do indeed appear on page 15 of the NAS report2. The very next, and concluding, sentence of that section was, however, not included in the quote. It states: “Despite these limitations, the steering committee reached the following conclusions: restricting our focus to those studies involving the highest levels of exposure to biomechanical stressors . . . the positive relationship between the occurrence of musculoskeletal disorders and the conduct of work is clear,” and “there is compelling evidence from numerous studies that as the amount of biomechanical stress is reduced, the prevalence of musculoskeletal disorders in the affected body region is likewise reduced.”2 Nor do Szabo and King make any mention of the final conclusions of the NAS report, which are listed on pages 27 and 28 of that document. These are:
(1) There is a higher incidence of reported pain, injury, loss of work, and disability among individuals who are employed in occupations where there is a high level of exposure to physical loading than for those employed in occupations with lower levels of exposure.
(2) There is a strong biological plausibility to the relationship between the incidence of musculoskeletal disorders and the causative exposure factors in high exposure occupational settings.
(3) Research clearly demonstrates that specific interventions can reduce the reported rate of musculoskeletal disorders for workers who perform high risk tasks. No known single intervention is universally effective. Successful interventions require attention to individual, organizational and job characteristics, tailoring the corrective actions to those characteristics2.
Thus, although Szabo and King are correct in stating that the NAS report found the literature on the subject to be imperfect (and what scientific literature is not?), they fail to convey the fact that the NAS report clearly concluded that the available evidence was quite sufficient to tie certain injuries to repetitive activity and that ergonomic interventions (that is, interventions designed to reduce biomechanical stress) were effective in reducing these injuries.
There are similar problems with other citations. For example, Szabo and King cite the article by Atroshi et al.3 to support the statement that “the prevalence of carpal tunnel syndrome is the same whether or not people perform repetitive activities.” Yet Atroshi et al. reported that the prevalence of CTS was 5.4% for those doing as little as one hour of repetitive work per day compared with 1.8% for those doing no repetitive work, a highly significant difference (p < 0.001). Atroshi et al. further noted that excessive wrist flexion and exposure to vibration also were associated with a significantly higher prevalence of CTS in their population-based study.
As a final observation, it is ironic that this article appeared at the same time as an article in BMJ by Macfarlane et al., who reported that a prospective analysis of nearly 2000 individuals showed that both repetitive activity (relative risk, 4.1) and workplace dissatisfaction (relative risk, 4.7) were important risk factors for the work-related musculoskeletal symptom of forearm pain4. It seems reasonable to conclude that both repetitive work and psychosocial factors are important predictors of musculoskeletal symptoms in the workplace, such as those experienced by the workers in the keyboard lawsuits. Moreover, numerous studies of humans2,3,5-12 and animals13-16 have shown that repetitive loading13-16, vibration7,9,12, and awkward posture3,17 can produce a host of musculoskeletal pathologies, including disc degeneration15, tendon degeneration13,16, rotator cuff disease14, and carpal tunnel syndrome3,8,11,18, as well as regional pain such as that studied by Macfarlane et al.4, which in many cases may be due to exercise-induced muscle injury5,19-22.
In short, although this paper is certainly a well-documented summary of the keyboard/RSI legal defense, I found it rather disappointing in its attempt to serve as a Current Concepts Review of the broader topic of repetitive activity in the workplace and in its broad, poorly documented critiques of repetition as a potential cause of musculoskeletal injury and of the field of ergonomics in general. This broader subject deserves more thorough coverage in the pages of The Journal of Bone and Joint Surgery.
Peter C. Amadio, MD
Mayo
Clinic
200 First Street S.W.
Rochester, MN 55905
E-mail address: pamadio@mayo.edu
To
The Editor:
Dr. Szabo and Atty. King’s Current Concepts Review, “Repetitive
Stress Injury: Diagnosis or Self-Fulfilling Prophecy?” (82-A: 1314-1322, Sept.
2000), raises a number of important issues for all orthopaedists. Their position
is cause for concern for three reasons. First, their attempt to debunk computer
keyboards as a cause of a work-related musculoskeletal disorder (WRMSD) might
lead the reader to decide that there is little scientific information about the
causation or prevention of all WRMSDs. That simply is not true. Second, like the
American Academy of Orthopaedic Surgeons, they assert that there currently is
insufficient scientific information about WRMSDs. This statement puts our profession
in a tenuous position and raises the question, “Do we apply a different standard
regarding the scientific basis for many of our diagnoses and treatments compared
with that for WRMSDs?” Third, they infer that many of these syndromes are “functional
somatic symptoms” and cite the Australian experience. Perhaps some WRMSDs have
a “functional somatic component,” but if we generalize that bias to most of our
patients with WRMSDs we risk losing our hard-earned position as their advocate.
This article comes at a time when the Academy has taken the public position that there is inadequate scientific information for the Occupational Safety and Health Administration (OSHA) to increase the regulation of American industries by including more ergonomic interventions. As a former CEO of a large health-care organization, I experienced firsthand the negative impact of OSHA’s overbearing policies. It is difficult to separate the science from the public policy debate, but as orthopaedists we need to take a more even-handed approach.
In 1986, Dr. Vert Mooney and I co-authored a Current Concepts Review entitled “Occupational Orthopaedics.”23 We summarized the then-available literature and concluded that the data on many (but not all) upper-extremity and spinal disorders were sufficiently convincing to ascribe the workers’ symptoms to workplace causality. Furthermore, these conditions appeared to result from repetitive loads. Although a precise “dose-response” could not be quantified, a relationship did exist between symptoms, load, posture, and repetitions over time. Since that time, there has been a great deal of additional basic-science, epidemiological, and interventional research on this topic. Despite these data, Dr. Szabo and Atty. King iterate that there is insufficient scientific evidence for the determination of causality or prevention efficacy. Are we applying a double standard to how we view scientific merit?
A great deal of our diagnostic and therapeutic decisions in the day-to-day practice of orthopaedics are based on information that could be considered insufficient. For example, in 1992, Turner et al. synthesized the then-available data about spinal fusion24. Their study-selection criteria were far less stringent than the criteria used by the National Research Council in its deliberations on “Work-Related Musculoskeletal Disorders.”2 In the report by Turner et al., “articles were selected only if they reported at least 1 year follow-up data enabling the classification of clinical outcomes as satisfactory or unsatisfactory for at least 30 patients.” Only forty-seven articles met their criteria, and there were no randomized trials. Only four articles compared the outcomes for patients who had fusion with those for patients who had no fusion. Spinal fusion is often performed for patients receiving Workers’ Compensation. The clinical criteria that lead to the therapeutic decision often are vague, with the procedure being performed for such conditions as “degenerative disc disease,” “black disc disease,” and “segmental instability.” In population-based studies, the clinical outcomes are generally poor25. The truth is that a great deal of our clinical decisions still are based on retrospective, uncontrolled data that are no better, and quite possibly are less scientific, than the data supporting WRMSDs.
It is not my intention to debunk spinal fusion but to point out that, in comparison, the literature on WRMSDs includes a great deal of epidemiological data and prospective, randomized, controlled studies as well as documented case studies. It is perplexing that a profession that embraces “overuse syndromes” in athletes has difficulty accepting the notion that chronic repetitive trauma can cause symptoms, disorders, and even injuries in the workplace. One trip to an assembly plant will convince most observers that the “exposures” are at least as demanding as most athletics. In short, are we using a double standard to evaluate the literature?
The notion that many of these conditions are clouded by somatization puts us, as orthopaedists, in an awkward position as our patients’ advocates. The evolution of our understanding of disease usually starts with a description of symptoms. Often much later, physical signs or other sophisticated tests become available and the pathophysiology is then understood. One definition of somatization is the description of physical symptoms that cannot be confirmed by physical examination or other tests. Another definition adds the requirement for a likely psychological cause, of which depression and anxiety are common antecedents. Regardless of its definition, somatization is separable from malingering and factitious disorders, which are uncommon and for which the authors of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition: Primary Care Version (DSM-IV-PC) have established specific criteria. Somatization, depression, and anxiety (but not malingering) are common attributes of patients with chronic, disabling musculoskeletal conditions related or unrelated to the workplace. It is also true that compensation is associated with a greater risk for later disability26 as well as later litigation27. Whether intended or not, the context of the authors’ remarks might lead the reader to conclude that the majority of WRMSDs are minimally related to physical exposures and are predominantly due to psychological dysfunction. The Academy’s, and I presume the authors’, legitimate concerns about OSHA’s often misguided application of public policy cannot be allowed to override our more fundamental concern for our patients.
To the four responsibilities listed by the authors, I would add a fifth. As clinicians treating patients, we need to better understand the environment in which patients work and the physical and psychosocial stresses to which they are subjected. One trip to an assembly line or a construction site will convince most that many workers experience major physical stresses. If we believe that our patients’ recovery is impeded by significant psychosocial issues, isn’t it is our responsibility to direct the patients to the appropriate health professionals? To paraphrase Sir William Osler, we should be more concerned about the patient who has a disease than we are about the disease that the patient has.
Note: The author of this letter serves on the second Institute of Medicine Task Force. The opinions represented here are solely his own.
John Frymoyer,
MD
1450 Braeloch Road
Colchester, VT 05446
E-mail address: tofrys@aol.com
Dr. Szabo and Atty. King reply:
We agree with Dr.
Amadio that “it is undoubtedly true that the evidence associating keyboard use
with specific injuries is weak, that the benefit of ergonomically motivated changes
in keyboard design is unknown, and that the use of the term RSI as a specific
diagnosis is ill-advised.” But, having made this concession, Dr. Amadio falls
prey to the same faulty logic and unsupported assertions that have so often characterized
the debate on this issue while, in the meantime, patients continue to be misdiagnosed
with “repetitive stress injuries” attributed to poor ergonomics. In his letter,
Dr. Amadio prefaces purported scientific conclusions regarding the curative power
of ergonomics and the evils of repetition with tepid phrases such as “one can
only speculate” and “it seems reasonable to conclude that.” The use of such phrases
demonstrates the lack of scientific support for the points he makes. As one who
holds himself out as a scientist, Dr. Amadio should know better. We address several
of his more flagrant misstatements in turn.
Dr. Amadio confidently declares that we “greatly overstate the magnitude and locus of the problem, possibly because [we] use outdated data.” However, he then mischaracterizes the very data upon which his statement is based. For example, a review of the same data to which he refers reveals that the number of “disorders associated with repeated trauma” increased from 22,600 in 1982 to 332,100 in 1992 and then declined modestly to 253,300 in 1998 (the most recent estimate). All reported illnesses associated with any specific work or activity rose from 105,600 in 1982 to 514,700 in 1992 and similarly declined to 392,000 in 1998. When one considers that the events attributed to repeated trauma have risen from 21% to 65% of all reported illnesses from 1982 to 1998, we believe that we stated accurately the “magnitude” as well as the “locus” of the problem.
Similarly misguided is Dr. Amadio’s reliance on the conclusions of the National Academy of Sciences (NAS) report. As we state quite clearly in our article, the NAS rendered its conclusions about “biomechanical loads and biomechanical stressors” notwithstanding what it acknowledged to be severe limitations in the literature. Our point, which Dr. Amadio apparently missed, is that the conclusions drawn by the NAS committee are not supported by meaningful data, and its concession that it is “difficult to make strong causal references on the basis of the evidence from any individual study” admits just that. When we last checked, science is not based on leaps of faith but on meaningful data. There are simply no studies, and Dr. Amadio has cited none, that show that ergonomics prevents injury28.
At a minimum, Dr. Amadio’s mixing of definitions and concepts illustrates how individual studies are often misinterpreted in this area to serve one’s own ends. Thus, Dr. Amadio states that “there are similar problems with other citations” and cites an example where we accurately reported that Atroshi et al. found that “the prevalence of carpal tunnel syndrome is the same whether or not people perform repetitive activities.”3 More specifically, Atroshi et al. reported that the prevalence of carpal tunnel syndrome (CTS) was 2.4% for workers who performed activities involving repetitive hand or wrist motion compared with 2.7% for those who performed activities involving nonrepetitive motion (95% confidence interval for the difference, –2%, to –1.5%; p = 0.69)3. However, Dr. Amadio misrepresents Atroshi’s study with his statement that “Atroshi et al. reported that the prevalence of CTS was 5.4% for those doing as little as one hour of repetitive work per day compared with 1.8% for those doing no repetitive work” [italics added]. Actually, Atroshi et al. reported that the prevalence of CTS was 5.4% for working subjects who self-reported that they used the hand for activities involving excessive force for more than one hour per day compared with 1.8% for those who reported less frequent or no such use3. The amount of occupational exposure that corresponds with excessive force is not described, but excessive force is nevertheless a different measure than repetition.
We do not mean to denigrate the validity and benefits of ergonomics, and we regret if Dr. Amadio was left with that impression. Nonetheless, Dr. Amadio’s statement that the “definition of WRMSDs includes fractures, lacerations . . . and a variety of other specific conditions” is misleading and not germane to the discussion of whether or not ergonomics has reduced the incidence of “disabling conditions.” In our opinion, it is an injustice to the patient to rely on ergonomics to treat medical conditions. “Repetitive stress injury” is not a diagnosis, and the failure to make a correct diagnosis by labeling a patient with RSI is very harmful as witnessed in the numerous “repetitive stress injury” legal cases described in our report. The purpose of our article was to educate those physicians, particularly orthopaedists, who blindly get caught in the trap of labeling any upper extremity pain syndrome as a work-related “repetitive stress injury,” thereby embroiling the patient in the medicolegal Workers’ Compensation system and, consequently, providing a disincentive for the patient to get better. This serves neither the patient nor society.
Ergonomics cannot take credit for decreasing the incidence of well-recognized chronic disorders of the upper extremity such as carpal tunnel syndrome. Furthermore, there have been no reasonable interventional studies (that is, studies in which both outcome and exposure are measured and reported before and after an intervention) that have demonstrated a decrease in the prevalence of injuries to the upper extremity after the institution of ergonomic measures. An interventional study should by definition be designed like any prospective, randomized, controlled study. We have had the opportunity to review the literature and, to the best of our knowledge, there have been no such studies. This does not mean, as Dr. Amadio asserts, that we “reject entirely the legitimacy of research from another” discipline or that we are “questioning the legitimacy of ergonomics as a scientific discipline.” Rather, we recognize that ergonomics has some serious limitations. For example, we reported the results of a specific interventional study that clearly demonstrated that customary ergonomic measures such as keyboard design, splinting, rest periods, and workstation modifications did not relieve the incidence of “repetitive stress injury.” Before recommending ergonomic intervention legislation addressing mechanical factors in the workplace, which would cost society billions of dollars29, we believe that it is not too much to ask that these interventions be shown to be effective.
Perhaps most disappointing is Dr. Amadio’s touting of ergonomics as the reason for any decline in WRMSDs. Regarding the Bureau of Labor and Statistics (BLS) data, Dr. Amadio proclaims that “one can only speculate with regard to the reason for the decrease in reported work-related musculoskeletal problems, but ergonomic improvements in the workplace seem to be a logical candidate.” Not only do we disagree, but we further note the complete lack of a scientific approach to this “speculation,” which is characteristic of Dr. Amadio’s purported analysis of our manuscript. A complete review of the very BLS data he cites belies his theory. For example, not only was there a decrease in reported work-related musculoskeletal problems from 1992 to 1998, but there also was a parallel decline in cases of respiratory illnesses as well as in cases of poisoning and skin diseases. Similarly, there has been a decline in the rate of nonfatal injuries and illness among full-time workers in the agriculture, forestry, fishing, and construction industries30. Does Dr. Amadio speculate that these declines are also to be credited to ergonomic improvements? Simply put, Dr. Amadio’s logic is faulty and fails to distinguish between an association on one hand and causation on the other. Just because two variables are correlated does not mean that one causes the other. For instance, ice cream sales and the number of shark attacks on swimmers are correlated. Yet, in this case, both variables respond to changes in some unobserved third variable: ice cream sales and shark attacks both increase during the summer.
Are there competing hypotheses to explain the decline? As Susser stated: “Insofar as epidemiology is a science which by definition aims to discover the causes of health states, the search includes all determinants of a health outcome.”31 According to Linda Rosenstock, MD, director of the National Institute of Occupational Safety and Health (NIOSH), the workforce is aging and the incidence of injury decreases with age32. The shift from manufacturing to less hazardous service industries is creating safer working conditions32. Underreporting of actual workplace injuries and illnesses to avoid visits by Occupational Safety and Health Administration (OSHA) compliance officers has been proposed by some to explain at least part of the decline32, although others have refuted this explanation33. In short, we did not “speculate” as to which of these competing hypotheses is best supported by the data.
In his “final observation,” Dr. Amadio asserts that “it is ironic” that our paper was published simultaneously with the article in BMJ by Macfarlane et al. Yet in that study, it was found that workplace dissatisfaction was associated with a higher relative risk for forearm pain than was repetitive activity and that “no increased risk was associated with typing for more than 30 minutes without a break.”4 From these findings, Dr. Amadio confidently states that “it seems reasonable to conclude that both repetitive work and psychosocial factors are important predictors of musculoskeletal symptoms in the workplace, such as those experienced by the workers in the keyboard lawsuits.” Had Dr. Amadio had the benefit (as did one of the authors) of reviewing the medical records of the numerous plaintiffs who brought those lawsuits, he undoubtedly would have observed a myriad of medical factors associated with those symptoms. He also would have observed countless instances of patients mired in the Workers’ Compensation system who had been misdiagnosed with a “work-related repetitive stress injury” and been told that proper ergonomics could have prevented or even cured their condition. What we find ironic is that participants in Macfarlane’s study “who believed that they could rarely make their own decisions at work had double the risk of new onset of forearm pain.”4 While Dr. Amadio apparently acknowledges that psychosocial factors can account for such a large percentage of musculoskeletal symptoms in the workplace, he fails to acknowledge that these factors act as confounders and must be controlled for in studies that seek to establish causation.
Putting aside the fact that the ambiguous diagnoses of forearm pain and musculoskeletal symptoms are not synonymous with injury, we found it extremely troublesome that Dr. Amadio (and Dr. Frymoyer) do not acknowledge that low-force repetitive activities such as typing (which, as indicated by Macfarlane’s study, do not cause injury) are different from high-force/high-impact athletic activities. We also find it disappointing that Dr. Amadio failed to mention Macfarlane’s conclusions: “Psychological distress, aspects of illness behaviour, and other somatic symptoms are important predictors of onset of forearm pain in addition to work related psychosocial and mechanical factors. Misleading terms such as ‘cumulative trauma disorder’ or ‘repetitive strain injury,’ implying a single etiology should be avoided.”4
Kuhn, in his thesis on scientific revolutions, argued that the evidence that scientists draw upon is determined by an overriding contemporary paradigm that dictates the way in which a causal sequence is construed34. As studies like Macfarlane’s reveal the overriding role that psychosocial factors play in musculoskeletal symptoms associated with low-force repetitive jobs, we are likely to see a paradigm shift that will lead to more accurate diagnoses and better treatment and outcomes for our patients. If we want our patients to feel better, we must address the real causes of their pain. After all, would not Dr. Amadio and Dr. Frymoyer agree that this is what makes us better patient advocates?
Robert
M. Szabo, MD, MPH
Department of Orthopaedics
University of California,
Davis, School of Medicine
4860 Y Street
Sacramento, CA 95817
E-mail
address: rmszabo@ucdavis.edu
Kenneth J. King, JD
Brobeck, Phleger & Harrison
1633 Broadway,
47th Floor
New York, NY 10019
E-mail address: kking@brobeck.com
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