Obesity-Driven Exacerbation of Obstructive Sleep Apnea Severity in COPD: A Cross-Sectional Polysomnographic Study from Pakistan. Body Mass Index and Neck Circumference as Independent Predictors of Apnea Severity in the COPD–OSA Overlap

Abstract

Background Obesity is a major modifiable determinant of obstructive sleep apnea (OSA), yet its impact within the chronic obstructive pulmonary disease (COPD)–OSA overlap syndrome remains insufficiently characterised in South Asian populations, where distinctive body composition and limited polysomnographic resources pose unique diagnostic challenges (Riaz & Lodhi, 2024). Objective To evaluate the impact of obesity on OSA severity in patients with COPD and to determine whether body mass index (BMI) and neck circumference independently predict apnea–hypopnea index (AHI). Methods A cross-sectional study was conducted at the Sleep Laboratory, Khyber Teaching Hospital, Peshawar, enrolling 100 patients with spirometry-confirmed COPD (50 obese, 50 non-obese; BMI cut-off 30 kg/m²). Participants underwent anthropometric assessment, the STOP-BANG questionnaire, the Epworth Sleepiness Scale (ESS), and overnight polysomnography. Group differences were assessed using independent t-tests and chi-square analysis; multivariable linear regression identified independent predictors of AHI (p < 0.05). Results Obese patients demonstrated significantly higher AHI (32.4 vs. 18.2 events/hour; p < 0.001), lower minimum nocturnal oxygen saturation (76.5% vs. 83.9%; p = 0.01), and reduced sleep efficiency (72.8% vs. 78.6%; p = 0.04). BMI (β = 0.34, p = 0.001) and neck circumference (β = 0.29, p = 0.004) remained independent predictors of AHI after adjustment for age, sex, and smoking (model R² = 0.41, p < 0.001). Obese patients were more frequently classified High Risk on STOP-BANG (76% vs. 54%; p = 0.01) and had higher hypertension prevalence (48% vs. 30%; p = 0.04). Conclusion Obesity substantially aggravates OSA severity in patients with COPD. BMI and neck circumference are independent, cost-effective predictors of apnea severity and offer a practical screening strategy for early risk stratification in resource-constrained respiratory care settings.