Author Affiliation: Division of Cardiology, St Luke's–Roosevelt Hospital Center, Columbia University College of Physicians & Surgeons, New York, New York.
The study by Odden et al1 describes the risk-modifying effect of frailty (as assessed by walking speed) on the association of hypertension and all-cause mortality in elderly persons. The results of the study should be viewed in the context of 2 important epidemiologic phenomena: selective survival and competing risk. The apparent lack of detrimental effect of hypertension or even “protective” effect in very elderly persons is likely explained by the “natural selection” of individuals who are relatively immune to adverse cardiovascular effects of elevated high blood pressure.2 Their peers with normal blood pressure are likely to carry a higher burden of comorbidities that are associated with lower blood pressure values (including frailty), since the expected association of systolic blood pressure with age is linear. As the burden of comorbidities increases, the attributable risk of hypertension in all-cause mortality decreases, which was demonstrated in the study by walking speed stratification, a crude measure of frailty.
Argulian E. Hypertension and Mortality in the Elderly: Further Insights. JAMA Intern Med. 2013;173(4):325. doi:10.1001/jamainternmed.2013.1642