Objective: Heart rate (HR) was recommended by the European hypertension guidelines for risk assessment. Among unresolved issues in relation to HR as a risk factor, body position may be critical. We therefore investigated HR in the supine and sitting positions as predictors of mortality in an elderly population.
Methods: Our elderly (≥60 years) participants were recruited from a suburban town of Shanghai. HR in the supine and sitting positions was measured with two different validated automated oscillometric blood pressure monitors. Information on total and cardiovascular mortality was collected during follow-up.
Results: In the 4051 participants (44.6% of men, mean age of 68.6 years), HR at baseline was slower in the supine than sitting position (72.2 ± 13.9 vs. 76.3 ± 11.9 bpm, P < 0.0001). During 5.9 years (median) of follow-up, the cumulated number of person-years was 20 529, and total and cardiovascular deaths occurred in 376 and 186 participants, respectively. In a Cox regression model adjusted for covariates and mutually one for another, HR in the supine but not sitting position predicted total and cardiovascular mortality (both P < 0.0001). The hazard ratios associated with HR in the supine position were 1.19 (95% confidence interval, 1.11-1.29) and 1.25 (1.13-1.38) for 1-SD increase, respectively, and 1.53 (1.19-1.98) and 1.69 (1.19-2.40) for at least 75 vs. less than 75 bpm, respectively. The mortality risk increased continuously and significantly with HR in the supine position starting from 63 bpm.
Conclusion: Resting HR in the supine position may be preferred for risk assessment in the elderly.