Prevalence, predisposing factors, and prognostic importance of postural hypotension.

OBJECTIVES: To determine the prevalence and predisposing factors of postural hypotension and to evaluate the effect of postural hypotension on 10-year vascular mortality in an elderly population.
METHODS: A random sample of 480 subjects aged 65 years or older was obtained in 1982. The participation rate of the subjects in the study was 72%, for a total of 347 subjects. Orthostatic testing and continuous ambulatory electrocardiographic recording, as well as comprehensive clinical evaluation, including medical history, physical examination, standard electrocardiography, chest radiography, blood pressure measurement, routine biochemical analysis, and determination of body mass index, were performed. In 1992, the 10-year mortality of subjects and causes of death were recorded from the mortality statistics. Of the participants, 184 (53%) had died and 163 were still alive. To determine the effect of postural hypotension on the 10-year mortality, the subjects who were alive and those who had died of vascular or nonvascular causes were compared. All of the examinations had been completed in 156 subjects who were still alive, in 109 subjects who had since died of vascular causes, and in 64 subjects who had died of nonvascular causes.
RESULTS: An abnormal postural systolic blood pressure drop (-20 mm Hg or less) after standing for 3 minutes was demonstrated in 28.0% of subjects. There were no sex or age differences between the subjects with and without postural hypotension. No predisposing factors for postural hypotension other than elevated blood pressure were found. Chronic cardiovascular diseases, disability, body mass index, medication, and abnormal findings in ambulatory electrocardiographic monitoring were not associated with postural hypotension. In the univariate analysis, the extent of systolic or mean blood pressure change predicted neither vascular nor nonvascular death during the 10-year follow-up. On the other hand, diastolic blood pressure drop, in particular after standing for 1 minute, was associated with increased vascular mortality (odds ratio, 2.7; 95% confidence interval, 1.3 to 5.6). In the multivariate analysis, however, this association disappeared.
CONCLUSIONS: Postural hypotension was common in an unselected elderly population. No predisposing factors for postural hypotension other than elevated blood pressure were found. The 10-year follow-up showed that postural diastolic, but not systolic, blood pressure drop predicted excess vascular mortality. However, this association disappeared in the multivariate analysis, thus being related to background factors such as cardiovascular diseases.