Lower BMI is a predictor of obstructive sleep apnea in elderly Thai hypertensive patients

The prevalence of both hypertension and obstructive sleep apnea (OSA) are increased in patients with age greater than 60 years. We studied the clinical differences of OSA in hypertensive patients with age greater or less than 60 years. In addition, rate of OSA-induced hypertension in Thai population is limited.

We retrospectively reviewed medical records of patients treated at the hypertension/sleep clinic at Srinagarind Hospital, Khon Kaen University, between 2010 and 2011. The inclusion criteria used were hypertensive patients who had at least one symptom of OSA and had been tested for the sleep study. Rate and clinical features of OSA were studied and categorized by age of 69 years. Factors associated with likelihood of having OSA in hypertensive patients age over 60 years were identified by multiple logistic regression analysis.

During the study period, 49 patients met the criteria. Of those, 42 patients (85.71 %) had an apnea-hypopnea index (AHI) of more than 5/h. The average AHI was 22.22 ± 13.86 times/h. The common symptoms of OSA were snoring (100 %), daytime sleepiness (28.57 %), unexplained nocturia (28.57 %), and gastroesophageal reflux disease (28.57 %). The numbers of patients with age less than 60 years and more than 60 years were 20 and 22 cases, respectively. Most patients (88.10 %) had well-controlled blood pressure level. Only BMI was significantly associated with OSA-induced hypertension in patients aged over or equal to 60 years. The adjusted odds ratio was 0.743 (0.560, 0.985).

OSA is very common in Thai hypertensive patients aged 40-70 years who have at least one symptom of OSA. Lower BMI is a predictor of obstructive sleep apnea in elderly Thai hypertensive patients.