Effects of biological age on the associations of blood pressure with cardiovascular and non-cardiovascular mortality in old age: A population-based study

Background/objectivesWhether chronological or biological age may play a role in the association between blood pressure and cause-specific mortality in old age is unclear. We seek to investigate the associations of blood pressure with all-cause, cardiovascular, and non-cardiovascular mortality among older people and to explore whether chronological age and biological age may modify the associations.MethodsThis cohort study included 3014 participants (age ≥ 60 years, 64.0% women) from the Swedish National study on Aging and Care in Kungsholmen, Stockholm. In 2001-2004, data were collected through interviews, clinical examinations, and inpatient register. Survival status and causes of deaths till 2011 for all participants were ascertained from Swedish death register. Data were analyzed with Cox proportional hazard models for all-cause mortality, and Fine-Gray competing risks models for cause-specific mortality.ResultsDuring 23,788 person-years of follow-up (median per person, 8.4 years), 933 (31.0%) participants died. Systolic blood pressure < 130 mmHg (vs. 130-139 mmHg) was significantly associated with decreased all-cause mortality (hazard ratio = 0.59, 95% confidence interval = 0.40-0.87) and non-cardiovascular mortality (0.59, 0.36-0.98) in biologically young people (persons with neither cognitive impairment nor mobility limitation), but with increased all-cause mortality (1.63, 1.22-2.16) and non-cardiovascular mortality (2.18, 1.27-3.75) in biologically old people (persons with either cognitive impairment or mobility limitation). The hazard ratio of cardiovascular mortality was increased with increasing levels of systolic blood pressure (ptrend = 0.009) and diastolic blood pressure (ptrend = 0.008) in biologically young people.ConclusionsBiological age plays a pivotal role in the associations of blood pressure with cardiovascular and non-cardiovascular mortality in old age.