Is desaturation Index, a better predictor of metabolic syndrome than apnoea-hypopnoea index?

Introduction: Metabolic Syndrome (MetS) is strongly associated with obstructive sleep apnea (OSA), a combination often termed syndrome Z. There is wide individual variation in the duration of the apneas and hypopnoeas. Some have few but prolonged apneas, and others frequent but brief apneas. Prolonged apneas are associated with more severe hypoxia. Desaturation index (DSI) may correlate better with some of the complications and comorbidities of OSA than the Apnea Hypopnea Index(AHI), as the intermittent hypoxias causing oxidative stress may underlie the pathogenic mechanisms in OSA. Objective: To compare the relationship of DSI and AHI to MetS. Materials and methods: Polysomnography recordings in a level I sleep laboratory of 104 proven OSA patients were studied. AHI, DSI and desaturations were analyzed and compared for their association with MetS. Conclusion: Our study shows DSI and degree of desaturation are better predictors of MetS, and reducing nocturnal hypoxia is important in managing OSA.