Causal effect of potential risk factors on obstructive sleep apnea: a Mendelian randomization study

Observational epidemiological studies have revealed that multiple risk factors may be associated with the risk of obstructive sleep apnea (OSA). However, the causal relationship between them remains largely unknown. We aimed to investigate the causal relationship between potential risk factors and OSA risk. A two-sample Mendelian randomization approach was used to evaluate the causal association of 42 risk factors with OSA risk. Summary data on OSA were obtained from a recently published genome-wide association study including 16,761 patients with OSA. Suggestive associations with increased risk were observed for body mass index (OR = 2.19, 95% CI 1.99-2.42, P < 0.01), childhood body mass index (OR = 1.46, 95% CI 1.15-1.83, P < 0.01), overweight (OR = 1.43, 95% CI 1.17-1.74, P < 0.01), smoking initiation (OR = 1.27, 95% CI 1.09-1.49, P < 0.01), gastroesophageal reflux disease (OR = 1.60, 95% CI 1.40-1.82, P < 0.01), and depression (OR = 1.28, 95% CI 1.06-1.53, P = 0.01). Age at first birth (OR = 0.88, 95% CI 0.82-0.94, P < 0.01) and education (OR = 0.76, 95% CI 0.66-0.87, P < 0.01) were significantly associated with decreased risk of OSA. We found a causal effect for several potential risk factors on OSA risk, including obesity, smoking, education, age at first birth, gastroesophageal reflux disease, and depression.