[Analysis of clinical characteristics and risk factors of obstructive sleep apnea hypopnea syndrome with hypertension].

OBJECTIVE To study the risk factors contributing to the development of hypertension in patients with obstructive sleep apnoea hypopnea syndrome (OSAHS), and the clinical characteristics of OSAHS with hypertension. METHODS A total of 2397 OSAHS patients aged above 30 years old and diagnosed by the sleep-disordered breathing center of Guangxi between July 2012 and August 2015 were recruited. OSAHS patients with new-onset hypertension (OSAHS with hypertension group) and those without hypertension (simple OSAHS group) were identified and their clinical data, including general status, family history of hypertension or snoring, Epworth Sleepiness Scale (ESS) score for daytime sleepiness, physical examination findings, and polysomnography monitoring data were collected. OSAHS patients with new-onset hypertension (n=101) and OSAHS patients without hypertension (n=202) matched by age and body mass index (BMI) (age difference, 2 years; BMI difference, 1.5 kg/m(2)) were recruited in the OSAHS with hypertension group and the simple OSAHS group. A case-control study was used to compare the clinical characteristics of these two groups, and univariate and multivariate Logistic regression were used to analyze all the factors contributing to hypertension development besides age and BMI. RESULTS The average age and BMI of the OSAHS with hypertension group and the simple OSAHS group were respectively (46.2±9.3), (46.2±9.2) years old and (28.2±2.8), (28.2±2.8) kg/m(2). Patients in the two groups were well-matched with respect to age and BMI (P>0.05). The systolic blood pressure (SBP) and diastolic blood pressure (DBP) in the OSAHS with hypertension group were significantly higher than those in the simple OSAHS group at the first admission to the clinic and before and after the PSG examination. ESS values in the OSAHS with hypertension group and the simple OSAHS group were respectively 10.0±6.4 and 9.2±6.3 (P>0.05). There was no significant intergroup difference in neck circumference, waist circumference, duration of snoring, family history of snoring, and family history of hypertension (P>0.05) either. The apnea-hypopnea index (AHI) and apnea index (AI) in the OSAHS with hypertension group were higher than those in the simple OSAHS group (P<0.05); the longest apnea duration (LAD), mean apnea duration (MAD), and the total time spent with oxygen saturation below 90% (T90%) in the OSAHS with hypertension group were significantly longer than those in the simple OSAHS group (P<0.05). The minimal pulse oxygen saturation (MinSpO2) in the OSAHS with hypertension group was significantly lower than that in the simple OSAHS group (P<0.05). Six factors were identified to be associated with OSAHS with hypertension through univariate analysis: AHI (OR=0.985, P=0.001), AI (OR=0.983, P<0.001), LAD (OR=0.955, P=0.013), MAD (OR=0.874, P=0.015), MinSpO2 (OR=0.874, P=0.015), T90% (OR=0.997, P=0.036). Only MinSpO2 (P<0.001, OR=0.894) was closely related to OSAHS hypertension development in the multivariate Logistic regression model. CONCLUSIONS OSAHS patients with hypertension may show lower MinSpO2, higher AHI and AI, and longer LAD, MAD, and T90% than OSAHS patients without hypertension. MinSpO2 is probably closely related to OSAHS hypertension development.