- Email: [email protected]
Can some upper extremity disorders be defined as work-related?
Letters to the Editor
Can Some Upper Extremity Disorders Be Defined as Work-Related? To the Editor: It was with interest and concern that we reviewed the article by Vender et al. (Vender M[, Kasdan ML, Truppa KI.: Upper extremity disorders: a literature review to determine work-relatedness. J Hand Surg 20A:534-541, 1995). The article is faulty because it does not use standard criteria for causahty in evaluating scientific studies. It also uses inadequate methods for selecting and evaluating the literature as discussed below, and it ignores the widely accepted multi factorial model of causation for work-related disorders. For example, the Susser criteria for assessing causality include not only epidcmiologic studies but "also evaluating the coherence with existing knowledge supporting a specific hypolhesis, including biological plausibility. 1 The authors do not discuss any of these issues or review any of the science and literature underlyfi~g this important occupational health issue. The authors' inclusion of articles for review was a three-stage process, consisting of a check of three inclusion criteria: (I) that the title musl mention upper extremity disorder and work risk factors and that the authors should "be active" in the field or frequently cited in the literature, (2) a "medical review" of the outcome variable used, and (3) a validity review according to Stuck. 2 These inclusion criteria resulted in the exclusion of many relevant and informative studies. Moreover, the "medical review," emphasizing the importance of diagnosis versus symptoms and that the diagnosis should be acceptable to current medical practice of the authors (although the authors give no diagnostic criteria), rcslricted the re,~'icw to only 14 articles. It was only after lifts step that the Stock 9~.~aliditycriteria were applied, resulting in no acceptable studies on the relationship between clinical dis~ orders and physical work load factors. This approach eliminates many studies with good exposure assessmenl of work factors. For example, the study of Barnhart et al.,3 which included electro-
diagnosis as well as symptoms in their case definition of carpal tmmel syndrome, had detailed exposure assessment of ski equipment-manufacturing workers. The authors omitted studies that used published standardized clinical case delhaitions for epidemiologic studies (eg, Wafts et al.a) or clinically diagnosed cases. For example, Viikari-Juntura et al.s provided clinical definitions for epieondylitis in a study of meat-processing workers, as did Kurppa et al.~ in a prospective cohort study. Franklin et al5 used accepted workers' compensation claims with ICD-9 354.0 in studying the incidence of occupational carpal runnel syndrome. Some of the studies included as acceptable were case series rather than epidemiologic studies. Theh" inclusion greatly weakens the review since case series are not representative of working populations. To then apply epidemiologic criteria: to evaluate articles that are not epidemiologic studies (eg, Katz et al.~)--even if they happen to have workers in the clinical population--is irrelevant and inappropriate. In ending their review, the authors write that it is their opinion "that sufficient evidence does not exist in the medical literature to conclude that work is the sole cause of so-called 'cumulative trauma'." It is easy to agree with them, as we think that nobody has that opinion. Work is one of several factors. What is important is that work has modifiable risk factors that, when changed, often give long-lasting results. The World Health Organization 9 has specifically differentiated "work-related" from occupational diseases; work-related conditions have multifactorial etiologies, with work activities o1" conditions significandy contributing to the development, exacerbation, or acceleration of disease, but not acting as the sole cause. The term work-related musculoskeletal disorder, therefore, is appropfate nomenclature for the constellation of disorders that have bcen shown to have strong associations with one or more workplace exposures. It does not imply any specific causal mechanisms (eg, "repetitivc strain" "cumulativc trauma"). We agree with the authors that it is improper to label patients with eat ICD-9 diagnosis of a specific disorder in the absence of clirfical findings. Accordi ng The Iourna] of Hand Surgery
727
728
Letters t.o the Editor
to the authors, this may lead to unnecessary surgery and in some cases to permanent disability. The best effects m'e to be expected from preventive actions (ie, g o o d workplace and equipment design) that may eliminate the need for surgery. There are both ample evidence and mmaerous good reviews in the literature to support physical work-load factors as the risk factors for tenosynovitis, peritendinitis, and carpal tunnel syndrome. Lo-t3These reviews include epidemiologic studies as well as the underlying mechanisms that are biologically plausible. More research is always needed on exposure-effect relationships for the intensity, duration, and frequency of various exposures in order to more precisely target resources for intervention. Finally, we are puzzled by the authors' criticism of guidance and regulations that would require employers to record work-related musculoskeletal disorders and use this irfformation to identify and control associated tools, equipment, and methods. D o the authors 'advocate treating musculoskeletal disorders without consideration of what the patients do for 4 0 - 6 0 hours per week? Should we c o n f n u e to debate the issues of causality when the control of most associated work factors is technically and econotnically feasible?
7Jmmas Armstrong, Phi) Peter Buckle, PhD Lawrence Fine, MD, DrPH Mats Hagberg, MD, PhD Marie Haring Sweenev, PhD .ll~.a Kilbom, MD, DrMedSci Thomas LdublL MD Laura Punnett, ScD Gisela SjOgaard, PhD, DrMedSci Eira Viikeri-Juntura, MD, DrMedSci Correspondence to: Barbara Silverstein, PhD, MPH Research Director for SHARP Washington State Department of Labor and Industries P O. Box 44330 Olympia, WA 93504-4330
References 1. Susscr M. What is a cause and how do we know one? A grammea" for pragmatic epidemiolog3". Am J Epidemiol 1991;133:635~548.
2. Stock S Workplace ergontJmic factors and the dcvclopmerit of musculoskeletat disorders of the neck and upper limbs: a met&analysis. Am J Ind Met 1991 ;I 9:87-107. 3. Bamhart S, Demers P e t al. Carpal tunnel syndrome among ski manufacturing workers. Stand J Work Environ Health 1991. 4. W~is P, Kuorinka 1, Kurppa K et al. Epidemiologic screening of occupational neck and upper limb disorders: methods and criteria. Stand J Work Environ Health 1979:5(suppl. 3):25-38. 5. Viikari-Juntura E, Kurppa K et al. Prevalence of epicondylitis and elbow pain in the meat processing industry. Stand J Work Eeviron Health 1991; 17:38-45. 6. Kurppa K, VSkari-Junmra E et al. Incidence of tenosynovifis or peritendinitis and epicondylitis in a meat processing factory. Stand J Work Environ Health 1991;t7:32-37. 7. Franklin G, Hang Jct al, Occupationat carpal tunnel syndrome in Washingl.on state, 1984-1988. Am J Pub Health 1991 ~Sl '.741-746. 8. Ka~z J, Larstm Met al, Validation of a surveillance definition of carpal tunnel syndrome. Am J Pub Heakh 1991 ;8] :189-193. 9. WHO, Identilication and control tff work-related diseases. 1985; Technical Report 714, Geneva. 10. Hagberg M, Morgenstern H, Kelsh. Impact of occupations mid jeb tasks oa the prevalence of carpal tunnel syndrome: a review. Scand J Work Environ Healtt~ 1992;]8:337-345. 11, Hagberg M, Silverstein Bet al. In: Kuorinka 1, Fourcier L, cds. Wo&-related musculoskeletat disorders: a reference manual for prevention. London: Taylor and Francis, 1995:17-137, 12. Gerr F, Lctz R, Landa'J_gan R Upper extremity nmscuIoskeletal disorders of occupational origirt. Annu key Pub Health 1991:543-566. 13. Moore JS. Ftmct~on,strttctnre and response of compollents of the muscle-tendon unit. Occup Met 1992;7:713-740.
ln Reply: We were pleased to see the interest in our paper by 11 members of the official-sounding "Scientific Committee for Mnsculoskeletal Disorders within the International Commission of Occupational Health." This brings to mind the collection of essays by 100 physicists attempting to discredit one of our greatest Nobel laureates, One Hundred Authors AgairL~t Einstein. He reputedly responded, "Were m y theory wrong, it would have taken but one person to show it.''1 The authors of this letter suffer from a cumulative lack of clinictd experience, ff they wish to give credence to their future efforts, then they shouM have experienced hand surgeons on their investigative team. Collectively, our public will be served well only when the epidemiotogists, ergonomists, and clinicians cooperate to produce some truly meaningful data. All the rest is paper without just purpose.
Can Some Upper Extremity Disorders Be Defined as Work-Related? To the Editor: It was with interest and concern that we reviewed the article by Vender et al. (Vender M[, Kasdan ML, Truppa KI.: Upper extremity disorders: a literature review to determine work-relatedness. J Hand Surg 20A:534-541, 1995). The article is faulty because it does not use standard criteria for causahty in evaluating scientific studies. It also uses inadequate methods for selecting and evaluating the literature as discussed below, and it ignores the widely accepted multi factorial model of causation for work-related disorders. For example, the Susser criteria for assessing causality include not only epidcmiologic studies but "also evaluating the coherence with existing knowledge supporting a specific hypolhesis, including biological plausibility. 1 The authors do not discuss any of these issues or review any of the science and literature underlyfi~g this important occupational health issue. The authors' inclusion of articles for review was a three-stage process, consisting of a check of three inclusion criteria: (I) that the title musl mention upper extremity disorder and work risk factors and that the authors should "be active" in the field or frequently cited in the literature, (2) a "medical review" of the outcome variable used, and (3) a validity review according to Stuck. 2 These inclusion criteria resulted in the exclusion of many relevant and informative studies. Moreover, the "medical review," emphasizing the importance of diagnosis versus symptoms and that the diagnosis should be acceptable to current medical practice of the authors (although the authors give no diagnostic criteria), rcslricted the re,~'icw to only 14 articles. It was only after lifts step that the Stock 9~.~aliditycriteria were applied, resulting in no acceptable studies on the relationship between clinical dis~ orders and physical work load factors. This approach eliminates many studies with good exposure assessmenl of work factors. For example, the study of Barnhart et al.,3 which included electro-
diagnosis as well as symptoms in their case definition of carpal tmmel syndrome, had detailed exposure assessment of ski equipment-manufacturing workers. The authors omitted studies that used published standardized clinical case delhaitions for epidemiologic studies (eg, Wafts et al.a) or clinically diagnosed cases. For example, Viikari-Juntura et al.s provided clinical definitions for epieondylitis in a study of meat-processing workers, as did Kurppa et al.~ in a prospective cohort study. Franklin et al5 used accepted workers' compensation claims with ICD-9 354.0 in studying the incidence of occupational carpal runnel syndrome. Some of the studies included as acceptable were case series rather than epidemiologic studies. Theh" inclusion greatly weakens the review since case series are not representative of working populations. To then apply epidemiologic criteria: to evaluate articles that are not epidemiologic studies (eg, Katz et al.~)--even if they happen to have workers in the clinical population--is irrelevant and inappropriate. In ending their review, the authors write that it is their opinion "that sufficient evidence does not exist in the medical literature to conclude that work is the sole cause of so-called 'cumulative trauma'." It is easy to agree with them, as we think that nobody has that opinion. Work is one of several factors. What is important is that work has modifiable risk factors that, when changed, often give long-lasting results. The World Health Organization 9 has specifically differentiated "work-related" from occupational diseases; work-related conditions have multifactorial etiologies, with work activities o1" conditions significandy contributing to the development, exacerbation, or acceleration of disease, but not acting as the sole cause. The term work-related musculoskeletal disorder, therefore, is appropfate nomenclature for the constellation of disorders that have bcen shown to have strong associations with one or more workplace exposures. It does not imply any specific causal mechanisms (eg, "repetitivc strain" "cumulativc trauma"). We agree with the authors that it is improper to label patients with eat ICD-9 diagnosis of a specific disorder in the absence of clirfical findings. Accordi ng The Iourna] of Hand Surgery
727
728
Letters t.o the Editor
to the authors, this may lead to unnecessary surgery and in some cases to permanent disability. The best effects m'e to be expected from preventive actions (ie, g o o d workplace and equipment design) that may eliminate the need for surgery. There are both ample evidence and mmaerous good reviews in the literature to support physical work-load factors as the risk factors for tenosynovitis, peritendinitis, and carpal tunnel syndrome. Lo-t3These reviews include epidemiologic studies as well as the underlying mechanisms that are biologically plausible. More research is always needed on exposure-effect relationships for the intensity, duration, and frequency of various exposures in order to more precisely target resources for intervention. Finally, we are puzzled by the authors' criticism of guidance and regulations that would require employers to record work-related musculoskeletal disorders and use this irfformation to identify and control associated tools, equipment, and methods. D o the authors 'advocate treating musculoskeletal disorders without consideration of what the patients do for 4 0 - 6 0 hours per week? Should we c o n f n u e to debate the issues of causality when the control of most associated work factors is technically and econotnically feasible?
7Jmmas Armstrong, Phi) Peter Buckle, PhD Lawrence Fine, MD, DrPH Mats Hagberg, MD, PhD Marie Haring Sweenev, PhD .ll~.a Kilbom, MD, DrMedSci Thomas LdublL MD Laura Punnett, ScD Gisela SjOgaard, PhD, DrMedSci Eira Viikeri-Juntura, MD, DrMedSci Correspondence to: Barbara Silverstein, PhD, MPH Research Director for SHARP Washington State Department of Labor and Industries P O. Box 44330 Olympia, WA 93504-4330
References 1. Susscr M. What is a cause and how do we know one? A grammea" for pragmatic epidemiolog3". Am J Epidemiol 1991;133:635~548.
2. Stock S Workplace ergontJmic factors and the dcvclopmerit of musculoskeletat disorders of the neck and upper limbs: a met&analysis. Am J Ind Met 1991 ;I 9:87-107. 3. Bamhart S, Demers P e t al. Carpal tunnel syndrome among ski manufacturing workers. Stand J Work Environ Health 1991. 4. W~is P, Kuorinka 1, Kurppa K et al. Epidemiologic screening of occupational neck and upper limb disorders: methods and criteria. Stand J Work Environ Health 1979:5(suppl. 3):25-38. 5. Viikari-Juntura E, Kurppa K et al. Prevalence of epicondylitis and elbow pain in the meat processing industry. Stand J Work Eeviron Health 1991; 17:38-45. 6. Kurppa K, VSkari-Junmra E et al. Incidence of tenosynovifis or peritendinitis and epicondylitis in a meat processing factory. Stand J Work Environ Health 1991;t7:32-37. 7. Franklin G, Hang Jct al, Occupationat carpal tunnel syndrome in Washingl.on state, 1984-1988. Am J Pub Health 1991 ~Sl '.741-746. 8. Ka~z J, Larstm Met al, Validation of a surveillance definition of carpal tunnel syndrome. Am J Pub Heakh 1991 ;8] :189-193. 9. WHO, Identilication and control tff work-related diseases. 1985; Technical Report 714, Geneva. 10. Hagberg M, Morgenstern H, Kelsh. Impact of occupations mid jeb tasks oa the prevalence of carpal tunnel syndrome: a review. Scand J Work Environ Healtt~ 1992;]8:337-345. 11, Hagberg M, Silverstein Bet al. In: Kuorinka 1, Fourcier L, cds. Wo&-related musculoskeletat disorders: a reference manual for prevention. London: Taylor and Francis, 1995:17-137, 12. Gerr F, Lctz R, Landa'J_gan R Upper extremity nmscuIoskeletal disorders of occupational origirt. Annu key Pub Health 1991:543-566. 13. Moore JS. Ftmct~on,strttctnre and response of compollents of the muscle-tendon unit. Occup Met 1992;7:713-740.
ln Reply: We were pleased to see the interest in our paper by 11 members of the official-sounding "Scientific Committee for Mnsculoskeletal Disorders within the International Commission of Occupational Health." This brings to mind the collection of essays by 100 physicists attempting to discredit one of our greatest Nobel laureates, One Hundred Authors AgairL~t Einstein. He reputedly responded, "Were m y theory wrong, it would have taken but one person to show it.''1 The authors of this letter suffer from a cumulative lack of clinictd experience, ff they wish to give credence to their future efforts, then they shouM have experienced hand surgeons on their investigative team. Collectively, our public will be served well only when the epidemiotogists, ergonomists, and clinicians cooperate to produce some truly meaningful data. All the rest is paper without just purpose.