The effects of stochastic galvanic vestibular stimulation on human postural sway

BACKGROUND: Orthostatic hypotension (OH) predicts mortality in hypertensive persons with diabetes mellitus, but no increase in mortality has been found among random samples of home-dwelling persons with OH. We examined the risks of nonvascular and vascular deaths according to different definitions of OH among home-dwelling elderly persons. SUBJECTS AND METHODS: The study population consisted of all persons aged 70 years or older living in 5 rural municipalities (N=969), of whom 833 (86%) participated. Orthostatic tests were successfully carried out in 792 persons by nurse examiners. Orthostatic hypotension was defined as a systolic blood pressure (BP) drop of 20 mm Hg or more or a diastolic BP drop of 10 mm Hg or more 1 minute or 3 minutes after standing up. Nonvascular and vascular deaths during the follow-up period were recorded. Data on diseases, symptoms, medications, the results of clinical examinations and tests, functional ability, and health behavior were collected at the beginning of the follow-up period. RESULTS: Of the sample, 30% had OH: the prevalence of systolic OH 1 minute and 3 minutes after standing up was 22% and 19%, respectively; that of diastolic OH 1 minute and 3 minutes after standing up was 6% for each. No differences in the occurrence of nonvascular deaths were found according to any of these definitions. By Cox multivariate regression analysis, the hazard ratio of vascular death associated with a diastolic BP reduction of 1 mm Hg 1 minute after standing up was 1.02 (P=.03), adjusted for systolic BP postural changes at 1 and 3 minutes and a diastolic BP change at 3 minutes. Adjusted for other significant factors associated with vascular death, the hazard ratio for vascular death associated with diastolic OH 1 minute after standing up was 2.04 (95% confidence interval, 1.01-4.15). The corresponding hazard ratio for systolic OH 3 minutes after standing up was 1.69 (95% confidence interval, 1.02-2.80). Using a cutoff point of 7 mm Hg or greater for a diastolic BP change 1 minute after standing up, the hazard ratio for vascular death was highest: 2.20 (95% confidence interval, 1.23-3.93). By logistic regression analysis, the baseline associates of diastolic OH 1 minute after standing up were dizziness when turning the neck (odds ratio [OR], 2.44), the use of a calcium antagonist (OR, 2.31), the use of a diuretic medication (OR, 2.29), a high systolic BP (OR, 2.23), and a low body mass index (OR, 2.26). The baseline associates of systolic OH 3 minutes after standing up were male sex (OR, 1.52), diabetes mellitus (OR, 1.92), a high systolic BP (OR, 2.91), and a low body mass index (OR, 1.68). CONCLUSIONS: The presence of diastolic OH 1 minute and systolic OH 3 minutes after standing up predict vascular death in older persons. They differ from each other in their prevalence and in several associates, suggesting different pathophysiologic backgrounds. Clinicians should prescribe vasodilating and volume-depleting medications with caution for elderly persons with diastolic OH 1 minute after standing up. Appropriate treatment of hypertension might be the best means to manage the different types of OH with poor vascular prognoses.