Frequency Distribution of Orthostatic Hypotension, Nocturnal Hypertension, and Postprandial Hypotension in Patients with Parkinson's Disease: A Case- Control Study

Orthostatic hypotension is a common autonomic dysfunction in Parkinson's disease. Major hypotheses proposed in the etiology of orthostatic hypotension include sympathetic denervation and treatment with dopaminergic drugs. The purpose of this study was to determine the contribution of each of the above factors in the incidence of orthostatic hypotension in patients with Parkinson's disease. The current study was conducted as a case-control study in the second half of 2008 and first half of 2009. The study population included patients with Parkinson's disease. Individuals who had received more than 500 mg/day levodopa for over 6 months were placed in the case group. Patients who had not received any levodopa until the time of the study were placed in the control group. Exclusion criteria were having a concomitant disease or taking medications that cause orthostatic hypotension. Study variables included demographic characteristics, severity of the disease, orthostatic hypotension, postprandial hypotension, and nocturnal hypertension. Using a mercury sphygmomanometer, the presence or absence of orthostatic hypotension was determined in all patients. Postprandial hypotension and nocturnal hypertension were identified using a portable device for ambulatory blood pressure monitoring. Hoehn and Yahr staging scale was used in order to identify the severity of the disease. The data was analyzed using appropriate descriptive and analytical tests (chi-square test and t-test) in SPSS16. Overall, 50 patients were studied in two groups of 25. No significant differences were observed between the two groups in terms of age, sex, and the severity of the disease. Therefore, the patients in the control group were appropriately matched with those in the case group (P > 0.05). The frequency distribution of orthostatic hypotension was 12% and 20% in the case and control groups, respectively. The corresponding values were 12% and 24% for the frequency distribution of postprandial hypotension and 40% and 56% for the frequency distribution of nocturnal hypertension. None of these frequency distributions were significantly different between the two groups. The severity of the disease was strongly related with the frequency distributions of orthostatic hypotension and postprandial hypotension (P < 0.001 and P = 0.015, respectively). However, it was not associated with the frequency distribution of nocturnal hypertension. Although the prevalence of orthostatic hypotension was different between the case and the control groups, the difference was not significant. On the other hand, the severity of the disease was strongly correlated with the prevalence of orthostatic hypotension and postprandial hypotension in patients with Parkinson's disease.