Screening Parameters for COPD-OSA Overlap Syndrome in COPD Patients: Indian Perspective

ABSTRACT

Introduction: As Indian patients have different predisposing morphological characteristics, we undertook this study to evaluate the clinical profile of overlap syndrome and compare them with COPD patients to find out the screening tools for obstructive sleep apnea (OSA) in Indian chronic obstructive pulmonary disease (COPD) patients. Aims and objectives: • To study the clinical profile of patients with overlap syndrome. • To compare them with COPD patients. • To develop screening tools for overlap syndrome in COPD. Materials and methods: A prospective case-control study was carried out in a tertiary care center. Overnight pulse oximetry was carried out for all COPD patients. Those having snoring or saw-tooth pattern on overnight oximetry were subjected to level 1 polysomnography. About 30 patients of overlap syndrome were compared with 65 COPD patients. Results: The mean age in overlap syndrome group (56.9 ± 6.86 years) was significantly lower (p < 0.01). The daytime PaO2 and lowest nocturnal saturation were significantly lower in overlap group. PaCO2 and forced expiratory volume at 1 second (FEV1) were significantly higher. For diagnosing overlap syndrome, the positive and the negative predictive values of snoring were 84.42 and 100%; of body mass index (BMI) ?25 kg/m2 were 86.67 and 98.88%; and of excessive daytime sleepiness were 37.57 and 97.86%, respectively. Conclusion: Absence of snoring and BMI <25 kg/m2 virtually rules out overlap syndrome. The EDS has a high false-positive rate for predicting OSA. Patients having overlap syndrome have poor daytime and nocturnal oxygenation despite good lung functions.