Sleep apnea rife in bipolar disorder
medwireNews: Obstructive sleep apnea (OSA) may affect a substantial proportion of patients with bipolar disorder, so could have a large impact on their health and mortality risk, say researchers.
At a minimum, it was present in 21% of the 482 patients assessed by Tammas Kelly (George Washington University, Washington, DC, USA) and colleagues.
However, this rate was derived only from the 114 patients who undertook a sleep study, 101 of whom were diagnosed with OSA. Of the whole group, 44.4% had a positive OSA screen on a self-report sleep apnea questionnaire (the American Sleep Apnea Association's OSA screen), but just 53% underwent a sleep study.
Accounting for published false-negative rates associated with self-report screening, the researchers estimate an overall OSA prevalence of 47.5%, which they concede "on the face of it seems high."
But they stress: "The findings in this study echo and magnify the previous recommendations for routine screening for OSA in patients suffering from a bipolar disorder."
Patients with a positive sleep apnea screen had a significantly higher average body mass index (BMI) than those with a negative screen, at 29.32 versus 24.6 kg/m2, and were significantly older, at 47.4 versus 42.4 years. On logistic regression analysis, only BMI was a significant predictor of having OSA confirmed in a sleep study.
Given the high prevalence of OSA in the study, the researchers suggest that it "may have a significant role in morbidity and mortality associated with the bipolar disorders."
They note that untreated OSA is thought to shorten lifespan by about 20 years, and has been linked to cardiovascular morbidity, diabetes, and increased systemic inflammation. The team also observes that accidents are a common cause of mortality in bipolar disorder patients, and OSA could conceivably contribute to this via sleep deprivation.
"The serious health consequences of OSA make it critically important to understand the scope of the prevalence of co-occurrence of OSA and bipolar disorders," write Kelly et al in the Journal of Affective Disorders.
Finally, they note that OSA is associated with neuroimaging abnormalities. "The high prevalence of OSA in patients with bipolar disorders raises the possibility that OSA may play a confounding role in the neurostructural studies of bipolar disorder patients," they say.
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Eleanor McDermid, Senior medwireNews Reporter