Factors associated with hypoxia and severity in patients with both obstructive sleep apnea syndrome and chronic obstructive pulmonary disease

OBJECTIVE: The frequent co-occurrence of obstructive sleep apnea syndrome (OSAS) and chronic obstructive pulmonary disease (COPD) gives rise to an overlap syndrome associated with a decline in patients’ health. Discerning the nuanced clinical presentations, polygraphy data, and hematological profiles of individuals with isolated OSAS from those with comorbid OSAS and COPD is crucial for tailoring effective therapeutic strategies. The present investigation seeks to delineate the demographic, clinical, polygraphy, and hematological features that differentiate patients with OSAS alone from those with concurrent OSAS and COPD, and further to evaluate the independent predictive value of COPD for OSAS severity. MATERIALS AND METHODS: In this cross-sectional analysis, 68 adults diagnosed with OSAS by overnight polygraphy were classified into two groups: OSAS-only (n = 49) and OSAS plus COPD (overlap syndrome, n = 19). Collected data encompassed demographics, comorbidities, sleep indices [including apnea-hypopnea index (AHI), oxygen desaturation index (ODI), and percentage of sleep time with oxygen saturation < 90% (t90%)], and routine hematological examinations. Group comparisons used appropriate statistical tests, and multivariable logistic regression evaluated predictors of severe OSAS. RESULTS: Compared with patients who had OSAS alone, those with overlap syndrome exhibited more severe sleep-disordered breathing and nocturnal desaturation: median AHI was higher (55.80 vs. 38.06; p = 0.01), ODI was increased (57.50 vs. 41.10; p = 0.03), and t90% was longer (32.20% vs. 19.00%; p = 0.03). Mean corpuscular volume (MCV) was also greater in the COPD group (p = 0.01). While COPD showed a trend toward being associated with severe OSAS (odds ratio 2.18), this association did not reach statistical significance (p = 0.36). Hypertension was more prevalent among patients with overlap syndrome and can suggest an elevated cardiovascular risk in this subgroup. CONCLUSIONS: The convergence of COPD and OSAS correlates with severe sleep apnea, intensified nocturnal hypoxemia, and an increased prevalence of hypertension, thereby highlighting the imperative for meticulous evaluation and personalized treatment paradigms in this patient population. Limitations inherent in this study, specifically the constrained sample size and cross-sectional methodology, necessitate circumspect interpretation of the findings and suggest the value of prospective, large-scale investigations to corroborate these observations.