COMPARISON OF SELF-REPORTED AND EXPERT-OBSERVED PHYSICAL ACTIVITIES AT WORK IN A GENERAL-POPULATION

Concerns about exposure assessment quality have impeded research to id entify risk factors for ergonomic disorders. We compared self-reported and expert-observed estimates of work-related physical factors for pa rticipants in a study of carpal tunnel syndrome (CTS). We analyzed dat a from 61 subjects, including 28 CTS cases and 33 controls randomly sa mpled from a case-central study with 417 participants. For 11 posture and manual materials handling factors, the median difference in mean e xposure between self-reported and expert-observed exposure at work was less than 1/2 hour a day. Measurements by the two methods in this stu dy agreed more often than expected by chance (median kappa 0.31 in cas es and 0.28 in controls). Kappa differed significantly by case-control status for two factors: bending at the waist (kappa 0.79 in cases ver sus 0.28 in controls, P = 0.01) and twisting of the forearm (kappa 0.4 5 in cases versus -0.02 in controls P = 0.02). Although imperfect expo sure information collected from workers' self-reports is useful far ma ny ergonomic epidemiology studies. (C) 1998 Wiley-Liss, Inc.