Obstructive Sleep Apnea and the Metabolic Syndrome

Jamie C.M. Lam; Mary S.M. Ip


Expert Rev Resp Med. 2009;3(2):177-186. 

In This Article

Association Between OSA and the Metabolic Syndrome

There is growing recognition of the common coexistence of OSA and various metabolic disorders besides obesity, and the association of OSA and the metabolic syndrome was coined ‘syndrome Z’ a decade ago.[25] Despite the ongoing debate regarding the value of defining the metabolic syndrome beyond that of identifying its currently accepted individual components,[23,24] one school of thought recently proposed that OSA may be considered another manifestation of metabolic syndrome.[26]

Although the literature abounds with studies on the association between OSA and different individual features in the metabolic syndrome, not many have addressed the relationship between OSA and the metabolic syndromic entity. Two case-controlled studies on Caucasian men reported a ninefold and sixfold risk, respectively, for independent association between OSA and metabolic syndrome.[27,28] Similarly, a study of community-based Chinese subjects showed a lesser, but still very high, association with OSA subjects at a fivefold risk of having the metabolic syndrome,[29] and a positive correlation between AHI and the number of metabolic components present. A case-controlled study in Japan found an independent association between OSA and metabolic syndrome in men, but not in women.[30] Other studies identified associations between sleep-disordered breathing and multiple metabolic factors within the metabolic syndrome, independent of obesity.[31,32,33,34] By contrast, a study in India reported that obesity, and not OSA, was the determinant of these metabolic derangements.[35]

Most studies on the effects of abolition of OSA by continuous positive airway pressure (CPAP) or other nonbehavioral treatment modalities focused on individual metabolic components as the primary outcome, and only a few have evaluated multiple components or the syndromic entity.[36,37,38] Significant improvements in more than one metabolic parameter were reported, although the improvement was not necessarily of sufficient magnitude to fall below the threshold for defining the metabolic syndrome.


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