Blood pressure and survival in the oldest old

OBJECTIVES: To determine the relationship between blood pressure (BP) and all-cause mortality in subjects aged 80 and older with hypertension. DESIGN: Retrospective cohort study with 5 years of follow-up. SETTING: Ten Veterans AFFAIRS (VA) sites. PARTICIPANTS: Four thousand seventy-one ambulatory patients aged 80 and older with hypertension. MEASUREMENTS: The outcome measure was likelihood of survival during the follow-up period. Vital status was obtained from VA and Social Security files. Variables collected for adjustment in Cox regression models were baseline BP, medications, demographics, diagnoses, and health-related quality of life (HRQoL); HRQoL information was available on 1,289 subjects based on Veterans Health Study Short From-36 (SF-36) questionnaire scores. RESULTS: Subjects with higher BP (up to a systolic BP (SBP) of 139 mmHg and a diastolic BP (DBP) of 89 mmHg) were less likely to die during follow-up than subjects with lower BP. After baseline adjustments, the hazard ratio for a 10-point increase in SBP was 0.82 (95% confidence interval (CI)=0.74-0.91), up to a SBP of 139 mmHg, and for DBP was 0.85 (95% CI=0.78-0.92), up to a DBP of 89 mmHg. There was no significant association between survival and BP levels in subjects with uncontrolled hypertension. CONCLUSION: In a cohort of very old, hypertensive veterans, in subjects with controlled BPs, subjects with lower BP levels had a lower 5-year survival than those with higher BPs. This suggests that clinicians should use caution in their approach to BP lowering in this age group.