A study published in Sleep Medicine assessed mortality in chronic obstructive pulmonary disease (COPD), obstructive sleep apnea (OSA), and overlap syndrome.
The investigators analyzed data from 2000 through 2018 on 355 participants. In the population, 16.1% of individuals had COPD alone, and 10.4% had COPD-OSA overlap syndrome. Forty-three percent of participants had neither disease. Participants were divided into four groups according to presence of COPD and moderate-to-severe OSA. A Cox model adjusted for demographic/anthropometric covariates and comorbidities to assess mortality. To evaluate prognostic performance, researchers compared the concordance index (C-index) between clinical model and extended models.
According to the results, people with COPD alone and COPD-OSA overlap syndrome had augmented all-cause mortality compared to those who had neither disease (adjusted hazard ratio=2.98 and 3.19, respectively). The C-indices of extended models with sleep time spent with peripheral capillary oxygen saturation (SpO2) <90% and mean SpO2 were significantly higher than that of clinical model (0.765 vs. 0.737 and 0.756 vs. 0.737, respectively; all P<0.05); however, the C-index of extended model with AHI was not (0.739 vs. 0.737; P=0.15), the researchers noted.
“In this cohort with symptoms of sleep apnea and airway disease, patients with overlap syndrome had increased mortality, but not higher than in those with COPD alone,” the researchers concluded. “The measurement of hypoxemic load, not AHI, better predicted mortality.”
Keywords: Chronic obstructive pulmonary disease, Hypoxemia, Mortality, Obstructive sleep apnea, Overlap syndrome