Non-reproducibility of wearable accelerometer methods in protective association between physical activity and cardiovascular disease: a cohort study.

BackgroundThe selection of accelerometer processing methods may influence the shape of the dose-response association between wearable-measured physical activity and health outcomes. We compared the association of stroke and myocardial infarction with Moderate-Vigorous Physical Activity (MVPA) assessed by three accelerometer-generated metrics: modified Euclidean Norm Minus One (ENMO), Machine learning (ML), and activity counts. MethodsWe computed MVPA durations in the UK Biobank accelerometer sub-cohort between 2013 and 2015. The outcomes, incident stroke and myocardial infarction, were followed up until December 2022. We used Cox regression and a restricted cubic spline to estimate the dose-response association for each of the three MVPA metrics. ResultsThere were 90,237 cardiovascular disease-free participants at baseline. We observed 1,298 incident strokes and 2,031 myocardial infarctions. For stroke, a linear decrease in hazard ratio was observed with ML, but not with ENMO and activity counts. For myocardial infarction, ML and ENMO showed a curvilinear decrease in hazard ratios, whereas activity counts showed a linear decrease. ConclusionThe dose-response associations between MVPA and cardiovascular disease varied markedly across the three accelerometer-derived MVPA metrics. Research using a single accelerometer metric may caution about the interpretation of the association.