Transitions in self-reported musculoskeletal pain and interference with activities among newspaper workers

Active surveillance of symptoms and disability due to musculoskeletal disorders (MSD) in working populations can map individual transitions in symptom intensity or disability level. Using repeat surveys, this study examined if aetiological risk factors for new symptoms or disability, measured by interference with activities, were similar to prognostic risk factors for subsequent outcomes of symptoms and disability. This paper reports on 379 Toronto newspaper workers who completed questionnaires in 1996 and 1997. Questions on pain/discomfort during the last year, episode frequency and duration formed the basis for constructing three mutually exclusive symptom levels: noncases (Level 1); mild cases (Level 2); and more severe or frequent pain cases (Level 3). A similar construction of overall interference levels was based on the frequency with which musculoskeletal pain/discomfort interfered with daily, recreational, social and family activities, or ability to do one's job during the previous 12 months. The last was also examined as work interference alone. Levels of symptoms were cross-tabulated by overall and work interference at the two time points and Markov models of transitions between states were formulated. Results indicate that period prevalence of symptoms and overall interference increased between phases, though only significantly for symptoms (Levels 2 and 3, 65.7-70.7%, p = 0.04), while work interference was unchanged (17.9-17.0%). Equivalent proportions of workers improved as worsened in symptoms (21.1 and 22.4%, respectively), overall interference (16.7 and 17.8%), and work interference (7.4 and 6.6%). The only significant predictor for those without work interference at time one was job tenure, which was protective against work interference (Odds Ratio (OR) 1.06, 95% Confidence Interval (CI) 1.01-1.12). Among those who had more severe/frequent symptoms at time one, lack of improvement over time was predicted by longer job tenure (OR = 0.92 per year, CI: 0.87-0.97), greater psychological demands of work (OR = 0.65 per point, CI: 0.51-0.84) and marginally by greater upper extremity disability score. At time one, women with work interference were more likely to have persistent interference at time two (OR = 7.22, CI: 1.57-33.20). Suggestive findings included opposite effects of social support at work: reduced risk of development of new symptoms but increased risk of persistence at the highest symptom level.