Orthostatic hypotension in genetically related hypertensive and normotensive individuals

OBJECTIVES: Prevalence and determinants of orthostatic hypotension remain largely unexplored in younger individuals without significant burden of chronic diseases. METHODS: We investigated frequency and main associations of impaired orthostatic response in a cohort of 469 middle-aged hypertensive patients and 453 of their normotensive first-degree relatives. RESULTS: 13.4% of hypertensive and 5.5% of normotensive study participants were found to have orthostatic hypotension. In a backward logistic regression the following determinants of orthostatic hypotension were identified: sex female, odds ratio (OR) 2.45, 95% confidence interval (CI) 1.14-5.25, P=0.022, reduced glomerular filtration rate OR (per ml/min/1.73 m2) 0.97, 95% CI 0.94-0.99, P=0.002, systolic OR (per mmHg) 1.02, 95% CI 1.00-1.05, P=0.047 and diastolic blood pressure OR (per mmHg) 1.04, 95% CI 1.00-1.09, P=0.033, and antihypertensive treatment (OR 0.41, 95% CI 0.18-0.93, P=0.034). In hypertensive patients use of angiotensin-converting enzyme inhibitors was related to lower orthostatic hypotension frequency. Percentage of orthostatic hypotension-positive patients in the highest blood pressure stratum (> or = 160 mmHg) decreased from 20.2 to 7.6, when diagnostic criteria of orthostatic hypotension were adjusted for mean systolic orthostatic reaction (2 SD value: 30 mmHg) . During follow-up (t=6.6 years) individuals with impaired orthostatic response showed a trend towards increased total mortality (OR 2.16, 95% CI 0.97-4.80, P=0.06) in a crude model. CONCLUSION: Prevalence of orthostatic hypotension in hypertensive patients is higher than in their normotensive first-degree relatives. Independently of age, sex, and elevated blood pressure, orthostatic hypotension may be additionally determined by impaired renal function. Antihypertensive treatment seems to protect from orthostatic hypotension, in particular, use of angiotensin-converting enzyme inhibitors in hypertensive patients. The diagnostic criteria of orthostatic hypotension may need adjustment for initial supine systolic blood pressure to increase clinical accuracy. The prognostic value of impaired orthostatic response regarding risk of cardiovascular disease and mortality remains uncertain and requires further studies.