The association between obstructive sleep apnea syndrome and metabolic syndrome: a confirmatory factor analysis

Background Growing evidence suggests an independent relationship between obstructive sleep apnea syndrome (OSAS) and metabolic syndrome (MS). Patients with OSAS always show clustering of metabolic components. However, the understanding of interplay between OSAS and metabolic components is still lacking. Methods Participants were consecutively enrolled from our sleep center during the period 2009–2013. Anthropometric variables, metabolic indicators, and sleep parameters were collected from all participants. The factor structure for MS in OSAS and non-OSAS was examined by confirmatory factor analysis. Results The OSAS and non-OSAS demonstrated clustering of metabolic components. MS in patients with OSAS was strongly associated with insulin resistance (standardized factor loading = 0.93, p < 0.001), obesity (loading = 0.92, p < 0.001), and the lipid profile (loading = 0.72, p < 0.001). Furthermore, insulin resistance was correlated with obesity and lipid profile ( r = 0.86, p < 0.001; r = 0.68, p < 0.001, respectively). Obesity and lipid profile were also highly correlated in OSAS ( r = 0.66, p < 0.001). In non-OSAS, MS was strongly associated with insulin resistance, obesity, and lipid profile (loading = 0.95, p < 0.001; loading = 0.74, p < 0.001; loading = 0.68, p < 0.001, respectively). Insulin resistance was most strongly associated with fasting insulin (loading = 0.65, p < 0.001). Lipid profile was most strongly associated with TG (loading = 0.88, p < 0.001). Obesity was most strongly associated with BMI (loading = 0.80, p < 0.001). Conclusions OSAS is more prone to show clustering of metabolic components compared with non-OSAS. In particular, insulin resistance, obesity, and the lipid profile were independently and strongly correlated with MS in OSAS.