Comparison of the severity of sleep-disordered breathing in Asian and Caucasian patients seen at a sleep disorders center

Race can be considered a risk factor for sleep-disordered breathing (SDB), with higher prevalences and greater severity of the disorder documented among persons of certain racial groups compared with others. Based on clinical observation, it was hypothesized that, other risk factors being equal, Asian patients with SDB have greater severity of their illness compared to Caucasian patients. A cross-sectional study was conducted at a sleep disorders clinic involving 105 Asian patients diagnosed as having SDB after undergoing polysomnography and 99 similarly diagnosed Caucasian patients matched for the following variables: age, gender and body mass index (BMI). The main outcome measure of interest was objective assessment of severity based on polysomnographic data of respiratory disturbance index (RDI) and minimum oxygen saturation (SaO(2)) during sleep. Symptom scores between patients of the two racial groups were also compared. There were significantly larger proportions of Asians compared to Caucasians with severe obstructive sleep apnea (OSAS) as defined by respiratory disturbance index (RDI) greater than or equal to 50 (25.0% vs 11.1%; P = 0.0288) or minimum oxygen saturation (SaO(2)) less than or equal to 69% (20.6% vs 4.2%; P = 0.0113). The mean minimum SaO(2) was significantly lower (P = 0.0001) while the mean (log transformed) esophageal pressure (Pes) value was significantly higher (P = 0.0090) in the Asian group. Logistic regression analysis showed that race was associated with severe SDB (RDI greater than or equal to 50) independent of age, sex and BMI. The estimated odds ratio for Asians having severe OSAS compared with Caucasians was 2.51 [95% Confidence Interval (CI) 0.98-6.64]. There was no significant difference in the severity of questionnaire-based symptoms of snoring, apneas during sleep and the median Epworth scores between Asian and Caucasian patients. Based on objective polysomnographic results, Asian patients with OSAS have greater severity of their illness compared to Caucasian patients matched for age, gender and BMI. There was, however, no significant difference in severity of questionnaire-based symptoms between Asian and Caucasian patients with SDB.