Journal of Occupational Rehabilitation, Vol. 10, No. 1, 2000 Describing the Burden of Upper-Extremity Musculoskeletal Disorders in Newspaper Workers: What Difference do Case Definitions Make? Dorcas E. Beaton, 1,2,4 Donald C. Cole, 1,3 Michael Manno, 1 Claire Bombardier, 1,2 Sheilah Hogg-Johnson, 1,2 and Harry S. Shannon 1,3 Musculoskeletal disorders (MSD) of the upper limb are of growing concern, although there is no consensus on how to define a “case” of MSD. Varying the case definition has been shown to alter the description of the prevalence of the disorder. The purpose of this study was to compare the symptom description as well as the burden (disability costs, time off work) of MSD across four different published case definitions. A survey was conducted at a large urban newspaper, and 1003 (84% response rate) people responded. The questionnaire included measures of pain (intensity, frequency, duration), disability, work disability, and absence. Case definitions permitted creation of four overlapping samples, which were compared descriptively on the various measures of burden of MSD. The case definitions led to different descriptions of burden associated with MSD. Contrasting between the two extremes (Hunting and NIOSH), differences were found in prevalence (55% vs. 20%), overall disability (14.6 vs. 23.2/100, 100 = more disability) and difficulty at work (8 vs. 15.5/100), and proportion reporting pain interfering with work (27.3 vs. 16.2%). The various case definitions drew samples that were described by different experiences in terms of burden. Studies using different case definitions therefore lack comparability. The definition to use may depend on the study goals (primary or secondary prevention for example). However, consensus on a common definition would allow comparability across studies. KEY WORDS: repetition strain injury; classification; burden; disability survey; questionnaire. INTRODUCTION Work-related musculoskeletal disorders (WMSDs) are a group of disorders of muscles, tendons, and nerves, which are caused or aggravated by work (1). They include specific disorders such as tendinitis or nerve compression as well as more general syndromes or 1 Institute for Work and Health, Toronto, Ontario, Canada. 2 Faculty of Medicine, University of Toronto, Toronto, Canada. 3 Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada. 4 Correspondence should be directed to Dorcas Beaton, Institute for Work and Health, 250 Bloor St East, Ste 702, Toronto, Ontario, Canada M4W 1E6. Tel.: (416) 927-2027; e-mail: dbeaton@iwh.on.ca. 39 1053-0487/00/0300-0039$18.00/0 C  2000 Plenum Publishing Corporation