Hypertension, obesity, smoking habit and relationship with obstructive sleep apnea syndrome

Objectives: Obstructive sleep apnea syndrome (OSAS) is associated with high cardiovascular risk. We have compared, in hypertensive patients with and without OSAS, blood pressure profile and risk factors that may be associated with the presence of OSAS.

Material and methods: We studied 130 hypertensive patients referred to our Sleep Unit with suspected OSAS, randomly chosen, of which 95 were OSAS and 35 non-OSAS. Patients answered a questionnaire on cardiovascular health. After 3 days without farmacological antihypertensive treatment were determined anthropometric measurements, office blood pressure, 24-hour ambulatory blood pressure monitoring, and a blood test. Statistical analises were performed using SPSS version 17. In the univariated analysis were used T test and Chi square test depending on quantitative or cualitative variables. Also a logistic regression model was used to identify sex, body mass index (BMI) and smoking habit as possible risk factors.

Results: We obtained two groups (hypertensive OSAS/hypertensive non-OSAS). (93.7%/80% male, p < 0.02), with a mean age (54.4 ± 8/52.8 ± 8.8) (age range 35/65) and BMI (33.1 ± 4.5/29.5 ± 8.8 kg/m², p < 0.01). 38.9% of OSAS were smokers, compared with 14.7% of non-OSAS. There were no significant differences in analytical values. Determination of office blood pressure: systolic (154.9 ± 18.5/148.0 ± 13.5, p < 0.04), diastolic (97.2 ± 11.5/93.2 ± 10.3, p < 0.02) and pulse pressure (57.7 ± 14.0/54.6 ± 9.3, NS). 52.7% of hypertensive OSAS subjects were non-dippers, and 34.2% of hypertensive non-OSAS (p < 0,05). Finally we performed a logistic regression model to evaluate the effects of sex, smoking and BMI as risk factors to develop OSAS.

Conclusions: Hipertensive patients with OSAS had significantly higher overall and night time systolic blood pressure, with a reduction in the fall in nocturnal blood pressure (systolic and diastolic), compared with hipertensive patients without OSAS. Using the logistic regression model, we found that obesity is 8.7 times higher risk for developing OSAS; male sex 8 times, and smoking 4.15 times. This regression model correctly classified 94.6% of OSAS, 45.8% for non-OSAS and 84.3% of all patients. Therefore, in OSAS patients we must consider the need for diagnosis and treatment of cardiovascular risk factors.