[A multi-center study on the association between sleep apnea and prevalence of hypertension]

To investigate the prevalence of hypertension among sleep apnea patients and the associated factors.

A total of 2297 patients (male 1310, female 211) from 20 teaching hospitals were enrolled in this study. Medical history interview, blood pressure measurement and an in-hospital polysomnogram were performed for all the patients. Questionnaires of sleep apnea and hypertension were finished by all the patients. SPSS 11.0 software package was used for data analyzing, and prevalence rates of hypertension were compared by chi-square test.

The prevalence of hypertension in the apnea hypopnea index (AHI) < 5/h group was 23.5%, but in AHI > or = 5/h group was 49.3%, the difference being significant. The prevalence of hypertension in the group with obstructive sleep apnea hypopnea syndrome (OSAHS) was 56.2%, but was 63.7% and 39.4% in the groups with and without hypertension family history, respectively. The odds ratio of hypertension in AHI > or = 5/h group was 3.167 times higher than in the AHI < 5/h group (OR = 3.167, 95% CI 2.953 - 5.426, P < 0.01). The prevalence of hypertension increased with AHI increases, and it was the highest in subjects with AHI of 16 - 20/h, but deceased slowly in subjects with AHI of 66 - 70/h. Two equations were formulated to show the relationship between AHI and the prevalence of hypertension: the prevalence of hypertension = 0.3199 + 0.0042 x AHI, and OR of the prevalence of hypertension = 1.018 + 0.017 x AHI. The AHI was an independent risk factor for the prevalence of hypertension after control for age, sex, BMI and family history of hypertension.

The prevalence of hypertension in subjects with sleep apnea was higher than those without sleep apnea. There was a close relationship between sleep apnea syndrome and the prevalence of hypertension. Sleep apnea was an independent factor for hypertension after control for the confounding factors.