Clinical Correlates of Low Blood Pressure in Very Old People: The Importance of Cognitive Impairment

OBJECTIVE: To identify the medical conditions associated with low blood pressure in very old people. DESIGN: A population-based, cross-sectional study. SETTING: Two neighboring communities in Stockholm, Sweden. SUBJECTS: Participants were 319 male and 1070 female participants, with the mean age of 85.0 years (SD = 5.8). MEASUREMENTS: Blood pressure recording, pulse rate counting, and Mini-Mental State Examination (MMSE) were conducted by trained nurses. Information on illness condition and activities of daily living (ADL) status was self-reported or gathered from proxy respondents. The computerized inpatient register system was also used for collecting the data of illness condition. Systolic pressure less than 130 mm Hg and diastolic pressure less than 70 mm Hg were defined as low systolic and diastolic pressure, respectively. MMSE score less than 24 was considered to indicate cognitive impairment. MAIN RESULTS: In multiple logistic regression analyses, low systolic pressure was related to slower pulse rate (< or = 60 per minute), heart failure, ADL limitation, and cognitive impairment, and low diastolic pressure was related to increasing age, slower pulse rate, cardiac dysrhythmia, ADL limitation, and cognitive impairment. People with diabetes mellitus were less likely to be in the low systolic pressure group. 34.9% of the prevalence of low systolic pressure, and 17.9% of the prevalence of low diastolic pressure was associated with cognitive impairment. CONCLUSIONS: Low blood pressure in the very old may be associated with poor functional status, cardiac insufficiency and, more importantly, cognitive impairment. It would be expected that low blood pressure is associated with increased mortality in this age group.