Multiple antihypertensive use and risk of mortality in residents of aged care services: a prospective cohort study

Aims The objective of this study is to investigate the association between multiple antihypertensive use and mortality in residents with diagnosed hypertension, and whether dementia and frailty modify this association. Methods This is a two-year prospective cohort study of 239 residents with diagnosed hypertension receiving antihypertensive therapy across six residential aged care services in South Australia. Data were obtained from electronic medical records, medication charts and validated assessments. The primary outcome was all-cause mortality and the secondary outcome was cardiovascular-related hospitalizations. Inverse probability weighted Cox models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause mortality. Covariates included age, sex, dementia severity, frailty status, Charlson's comorbidity index and cardiovascular comorbidities. Results The study sample (mean age of 88.1 +/- 6.3 years; 79% female) included 70 (29.3%) residents using one antihypertensive and 169 (70.7%) residents using multiple antihypertensives. The crude incidence rates for death were higher in residents using multiple antihypertensives compared with residents using monotherapy (251 and 173/1000 person-years, respectively). After weighting, residents who used multiple antihypertensives had a greater risk of mortality compared with monotherapy (HR 1.40, 95%CI 1.03-1.92). After stratifying by dementia diagnosis and frailty status, the risk only remained significant in residents with diagnosed dementia (HR 1.91, 95%CI 1.20-3.04) and who were most frail (HR 2.52, 95%CI 1.13-5.64). Rate of cardiovascular-related hospitalizations did not differ among residents using multiple compared to monotherapy (rate ratio 0.73, 95%CI 0.32-1.67). Conclusions Multiple antihypertensive use is associated with an increased risk of mortality in residents with diagnosed hypertension, particularly in residents with dementia and among those who are most frail.