Orthostatic hypertension: profile of a Nigerian population
Background: The aim of this study was to determine the prevalence, age, sex distribution and blood pressure (BP) pattern of patients with orthostatic hypertension in a cohort of hypertensives.
Method: A total of 179 patients on follow-up treatment in a hypertension clinic were assessed for age, sex and BP in the seated position, and after two minutes in the erect position, on three consecutive visits. Orthostatic hypertension was defined as an increase in systolic blood pressure (SBP) of ≥ 20 mmHg on more than one occasion in the erect position. Orthostatic hypotension was defined as a decrease in BP on more than one occasion, between the seated and erect SBP, of ≥ 20 mmHg. The mean ages of the participants with and without orthostatic hypertension were compared by t-test for any significant difference. The means of the seated SBP of participants with and without orthostatic hypertension were also compared with the t-test. The effect of gender on orthostatic hypertension was tested with a chi-square (χ²). The differences between the mean seated and mean erect SBPs of participants with and without orthostatic hypertension were compared with the paired t-test.
Results: Thirty-eight (21.23%) of the participants had orthostatic hypertension. The mean age of those with orthostatic hypertension was not significantly different from that of the participants without orthostatic hypertension (p-value = 0.789). There was no significant effect of gender on orthostatic hypertension (p-value = 0.795). The mean of the seated SBP was significantly lower in the participants with orthostatic hypertension (p-value = 0.008). The mean seated SBP was significantly different from the mean erect SBP for those with orthostatic hypertension, compared to those without orthostatic hypertension (p-value = 0.000 vs. p-value = 0.169). Five (2.79%) of the participants had orthostatic hypotension.
Conclusion: Orthostatic hypertension, a form of BP dysregulation, may be more common among treated hypertensives than what is presently known.
Keywords: orthostatic hypertension, prevalence, BP, Nigerians