Multifactorial relationships among the waist-to-hip ratio, insulin resistance, and obstructive sleep apnea in men: a large-scale cohort study

BACKGROUND: Metabolic comorbidities related to obstructive sleep apnoea (OSA) are a major concern in regarding OSA prognosis and complexity. However, few studies have investigated the interrelationships among these metabolic comorbidities. We explored the associations among insulin resistance (IR), the waist-to-hip ratio (WHR), and OSA using innovative and rigorous statistical methods. METHODS: We enrolled 5,326 subjects after meticulous recording anthropometric, biochemical, and standard polysomnographic parameters. The relationships among IR, WHR, and OSA were analyzed using confirmatory factor analysis (CFA) as well as moderation and mediation analyses. RESULTS: CFA showed that IR and obesity were strongly correlated (loading = 0.73, p < 0.001). OSA was associated with both obesity and IR (loading = 0.57, p < 0.001; loading = 0.46, p < 0.001, respectively). Obesity was strongly associated with both the body mass index (BMI) and the WHR (loading = 0.82, p < 0.001; loading = 0.67, p < 0.001, respectively). WHR served as a moderator; the interaction effect between WHR and IR on the apnoea-hypopnea index (AHI) was significant (coefficient = - 2.451; p = 0.023). Mediation analyses showed that WHR explained 14.93%, 14.02%, and 13.10% of the associations between IR and AHI, the oxygen desaturation index, and the micro-arousal index, respectively. CONCLUSION: Multifactorial relationships are apparent among IR, WHR, and OSA. The complex interrelationships highlight the intricate clinical interactions among metabolic dysfunction, central obesity, and sleep-disordered breathing, emphasizing the multifaceted nature of OSA and its related health implications.