Objectively measured versus self-reported occupational physical activity and multisite musculoskeletal pain: a prospective follow-up study at 20 nursing homes in Denmark

PURPOSE: To explore the prospective association of objectively measured and self-reported occupational physical activity (OPA) with multisite musculoskeletal pain (MSP) among Danish eldercare workers. METHODS: The study population consisted of eldercare workers in 20 Danish nursing homes (N = 553, response rate 59%, 525 female). Baseline data were collected in 2013–2014 and the 1-year follow-up was completed in 2016. At baseline, we measured objective OPA by a thigh-worn ActiGraph GT3X + accelerometer during work and self-reported OPA by a questionnaire survey. Information on musculoskeletal pain during the past four weeks in seven different body sites was reported by a structured questionnaire at baseline (n = 389) and by SMS and telephone interview during follow-up (n = 284). MSP was defined as having pain in two or more body sites. Using log-binomial models we calculated risk ratios (RRs) with their 95% confidence intervals (CIs) to estimate the association between objectively measured and self-reported OPA and MSP. RESULTS: We found statistically significant positive associations between self-reported OPA (RR for high OPA 1.24, 95% CI 1.05–1.46) and MSP while there was no significant association found between objective OPA and MSP. CONCLUSION: Our study indicates that self-reported, but not objectively measured OPA is positively associated with MSP. This finding highlights the need for better understanding, use, and interpretation of self-reported and objectively measured OPA in the study of MSP.