Prevalence and pattern of obstructive sleep apnea in chronic obstructive pulmonary disease patients from northern India

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BACKGROUND: Chronic obstructive pulmonary disease (COPD) is characterized by airflow limitation, hyperinflation, and ventilation-perfusion mismatch. It is now considered as a systemic disease. The prevalence of obstructive sleep apnea (OSA) in COPD is variable with a paucity of literature from Indian subcontinent. AIM: This study was conducted to observe the regional prevalence and pattern of OSA in patients of COPD. MATERIALS AND METHODS: The present prospective study was carried out in the Department of Internal Medicine, Pt. B.D. Sharma, PGIMS, Rohtak, for a period of 20 months, i.e. during July 2012 to February 2014. Patients seeking care at the Department of Internal Medicine and diagnosed with COPD formed the study population. COPD patients stable for at least 6 weeks were included in this study. Mild COPD patients, ischemic heart disease patients, any comorbid state, known case of OSA, and patients having COPD with acute exacerbation were excluded. The prescreening tools for the identification of OSA are Berlin sleep questionnaire and the Epworth sleepiness scale (ESS). Polysomnography was done using Somnologica studio 3.3.2 Embla N7000 sleep unit system. RESULTS: OSA with apnea–hypopnea index (AHI) ≥5/h was present in 10 out of 40 participants (25.0%). Berlin scores were found to be 0.10 ± 0.03 and 0.70 ± 0.04 in nonsleep-disordered breathing (SDB) and SDB participants, respectively. ESS scores were observed to be 2.60 ± 0.82 and 7.90 ± 2.51 between non-SDB and SDB participants, respectively. The difference in AHI between patients with non-SDB and SDB was statistically highly significant (1.36 ± 0.37, 13.41 ± 3.40; P CONCLUSIONS: The prevalence of OSA in COPD patients was found to be in the higher range. Sleep was significantly distorted in all its aspects in patients of COPD. ESS was found efficient in screening the patients of COPD for coexistent OSA. Berlin's questionnaire can be used to evaluate patients of overlap syndrome.