Combined effects of cognitive impairment and hypertension on total mortality in elderly people: the Kangwha Cohort study

Abstract

BACKGROUND: Previous studies have shown links between cognitive impairment and hypertension as well as mortality. However, combined effects of these two conditions on mortality have not been fully explored.

OBJECTIVE: To assess the combined effect of cognitive impairment and hypertension on all-cause mortality among the elderly people.

METHODS: We followed a cohort of 2,496 residents in Kangwha County, ranging in age from 64 to 101 years as of March 1994, for all-cause mortality for 11.8 years up to December 31, 2005. We calculated hazard ratios (HR) for all-cause mortality by cognitive status and blood pressure using the Cox proportional hazards model after having controlled for confounding factors.

RESULTS: 1,189 people (47.6%) died during the 11.8 years of follow-up. The HR associated with severe cognitive impairment increased from 2.15 (95% CI: 1.30, 3.54) for prehypertension over 2.68 (95% CI: 1.60, 4.48) for stage 1 hypertension to 3.60 (95% CI: 1.99, 6.49) for stage 2 hypertension in women. A mortality risk of 3.67 (95% CI: 2.05, 6.57) was observed among men who had both mild cognitive impairment and stage 2 hypertension.

CONCLUSION: Individuals with coexisting cognitive impairment and hypertension are at an increased risk of all-cause mortality compared with those with cognitive impairment or hypertension alone.