Sarcopenia and osteoporosis in tobacco- and non-tobacco-exposure-related chronic obstructive pulmonary disease

Sarcopenia and osteoporosis are important comorbidities in patients with chronic obstructive pulmonary disease (COPD). We compared the prevalence and impact of these comorbidities in tobacco-smoke-related COPD (S-COPD) and non-tobacco-smoke-related COPD (NS-COPD). The utility of rectus femoris ultrasonography as a screening tool for sarcopenia was also explored. This cross-sectional study was conducted in a tertiary care hospital in Southern India. The COPD Assessment Test (CAT), St. George's Respiratory Questionnaire, 6-minute walk test, dual energy X-ray absorptiometry and rectus femoris ultrasonography were performed in all included participants. One hundred participants (73% S-COPD and 27% NS-COPD, respectively) were included with a mean (standard deviation - SD) age of 65.8 (8.6) years and a mean (SD) predicted forced expiratory volume at one second of 41.1% (12.6). NS-COPD participants were younger (60.7 vs. 67.5 years; p<0.001), predominantly female (88.9% vs. 1.4%; p<0.001) and had a higher body mass index (BMI) (24.8 kg/m² vs. 21.8 kg/m², p=0.004) compared to S-COPD. Sarcopenia and osteoporosis were diagnosed in 36% and 12%, respectively. Older males with S-COPD and lower BMI were sarcopenic, and the latter was an independent predictor of lower 6-minute walk distance [adjusted b = -51.4 m; 95% confidence interval (CI) = -97.0, -5.84] and higher CAT scores (adjusted b = 2.53; 95% CI = 0.21, 4.86). Rectus femoris cross-sectional area at a cut-off value of 4.34 cm² had 91% sensitivity and 87% negative predictive value for sarcopenia. Sarcopenia was more prevalent among older male smokers and was an independent risk factor for high symptom burden and poor exercise capacity. Rectus femoris ultrasonography is a potential screening tool for sarcopenia.