O5A.6 Objectively assessed arm elevation and the course of neck and shoulder pain during a 2-year follow-up: a compositional approach. (April 2019) - Merkus, Suzanne
Abstract : Purpose: To use a compositional data analysis approach to study the association between the work/rest cycles of arm elevation and the course of neck and shoulder pain (NSP) during a 2 year follow-up in physically demanding occupations. Methods: Construction (n=59) and healthcare (n=59) employees wore accelerometers on the dominant upper-arm during a full working day at baseline. At baseline and every 6 months for two years, participants reported on NSP (scale 0–3). Duration of arm elevation within predefined ranges (<30°; 30–60°; 60–90°; and ≥90°) formed the parts of the composition. The work/rest cycles were defined as duration arm elevation in the parts≥30° relative to elevation <30°; the rest/work cycle was the duration arm elevation <30° relative to the total duration ≥30°. The isometric log-ratio transformed work/rest and rest/work cycles were associated to NSP at baseline (main effects; p-value<0.05) and changes in NSP over the 2 year follow-up (interaction effects with time; p-value<0.1) using linear mixed models, adjusted for confounders. Results: At baseline, the rest/work cycle was associated with higher pain (ß=0.22; p=0.063); the work/rest cycles were associated with lower pain (arm elevation 30–60° (ß=−0.27; p=0.080); 60–90° (ß=−0.14; p=0.295);≥90° (ß=−0.13; p=0.170) relative to <30°). None were statistically significant. Over the 2 year follow-up, there was a tendency for the rest/work cycle to be associated with a reduction in NSP (ß=−0.07; p=0.071), and the work/rest cycles to be associated with increased NPS (arm elevation 30–60° (ß=0.05; p=0.274); 60–90° (ß=0.09; p=0.032);≥90° (ß=0.02; p=0.445) relative to <30°). Conclusion: Having NSP at baseline likely shortened time-use with elevated arms, which may have contributed towards a reduction in NSP over the 2 year follow-up. Having lower NSP at baseline likely extended time-use with elevated arms, which may have contributed towards increased NSP over the 2 year follow-up.