Bolstering the Prognostic Utility of Coronary Risk Assessments with PAI: A Physical Activity Metric.

Purpose: Personal Activity Intelligence (PAI) translates heart rate during physical activity (PA) into a weekly score, that credits vigorous over low- and moderate intensity PA. We prospectively investigated the association between PAI and fatal and non-fatal coronary heart disease (CHD) in self-reported healthy participants from Norway, with specific reference to improving the accuracy of conventional coronary risk assessment.

Methods: We studied 40 961 healthy adults (56% women) from the population based Trøndelag Health Study (the HUNT study). Individual data were linked to hospital and cause of death registries. The weekly PAI score of each participant was divided into four groups (PAI scores of 0, ≤50, 51-99, or ≥ 100). Adjusted hazard ratios [aHRs] and 95% confidence intervals (CIs) for fatal and non-fatal CHD related to PAI were estimated using Cox proportional hazard regression analyses.

Results: During a median follow-up period of 13.1 years (IQR, 12.7-13.6), 3303 (3109 non-fatal, 194 fatal) CHD events occurred. Compared with the inactive group (0 PAI), weekly PAI scores at baseline of 51-99 and ≥ 100 were associated with a lower risk of CHD [0.80 (0.71-0.91) and 0.86 (0.78-0.95), respectively]. By adding PAI to traditional risk factors, the net reclassification improvement of CHD was 0.472 (P < 0.001).

Conclusions: PAI was inversely associated with CHD risk among healthy participants at baseline, and it's cardioprotective effect persisted across diverse risk factor profiles. A PAI score > 50 was substantially associated with a reduced risk of CHD. These findings have implications for improving the accuracy of conventional coronary risk assessments with PAI.