Describing the burden of upper-extremity musculoskeletal disorders in newspaper workers: What difference do case definitions make?

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