Polysomnographic comparison between Chinese and Caucasian patients with obstructive sleep apnea

Abstract

The Chinese population has a comparable prevalence of obstructive sleep apnea (OSA) compared to their Caucasian counterparts, but are notably less obese. Given this difference in body weight, Chinese patients could have a distinct OSA phenotype. We aimed to compare the characteristics of obstructive events in Chinese and Caucasian individuals matched for OSA severity. Chinese and Caucasian subjects with moderate-to-severe OSA (apnea–hypopnea index (AHI) ≥ 20events/h) were included in the study (n = 90) and matched for age, gender and AHI. Data were analysed to identify differences in event type, effect of sleep state and body position, degree of hypoxemia, and prevalence of metabolic risk factors. Data presented are Mean ± SEM or Median (IQR). Chinese subjects had a significantly lower body mass index (BMI) compared to AHI-matched Caucasian counterparts [27 (25–30) versus 34 (30–39) kg/m2, p < 0.001]. Chinese subjects had more apneas compared to Caucasian subjects [14.4 (5.8–31.8) versus 8.1 (2.2–20.7) events/h, p = 0.011]. Events were longer in the Chinese group (apnea: 25.1 ± 1.2 s versus 19.3 ± 1.3 s, p = 0.001; hypopnea 25.3 ± 1.0 s versus 22.9 ± 1.0 s, p = 0.03), but were associated with less hypoxemia (% time < 90%: 14.6 ± 2.5 versus 25.0 ± 3.7%, p = 0.01). Chinese individuals with moderate-to-severe OSA have a distinct phenotype characterised by longer and more frequent apneas, yet less hypoxemia, in the setting of a lower BMI, compared to Caucasians of equivalent disease severity. Postulated mechanisms include differing upper airway anatomy, control of breathing or lung reserve.