Sociodemographic correlates with prevalence of comorbidities in patients with chronic obstructive pulmonary disease: a study from a Chinese National Survey

Background An increase in the prevalence of comorbidities has been reported in patients with chronic obstructive pulmonary disease (COPD). However, contemporary estimates of the overall prevalence of the sociodemographic correlates of COPD comorbidities are scarce and inconsistent in China. This study aimed to investigate the prevalence of sociodemographic correlates of comorbidities in patients with COPD across China. Methods This was a cross-sectional study. We used data from the Enjoying Breathing Program between May 2020 and April 2022. Participants with COPD from 17 provinces (or equivalent) were included. Comorbidity clusters were stratified based on the number of comorbidities per person. Univariable and multivariable analyses were used to determine the sociodemographic associations of patients with COPD with specific clusters of comorbidities after adjusting for age, sex, and other prespecified covariates. Tetrachoric correlation analyses were performed to determine the associations between specific comorbidities. Findings A total of 3913 participants with COPD were included, of whom 1744 (44.7%) had at least one comorbidity; 25.4% had one comorbid disease, 12.9% had two, and 6.4% had three or more concurrent diseases. The most common comorbidities were hypertension (17.8%), asthma (9.9%), bronchiectasis (8.2%), diabetes (8.2%), and coronary artery disease (7.7%). In the logistic regression models adjusted for a broad set of factors, patients with COPD residing in the east region of China and having health insurance experienced a decreased likelihood of comorbidities (from OR = 0.70 [95% confidence interval [CI], 0.53-0.93] to OR = 0.50 [95% CI, 0.25-0.99]). However, patients over 80 years had increased risk (OR 1.43 [95% CI 1.01-2.03]), as did those in all Modified Medical Research Council (mMRC) grade categories (grade 1: OR = 1.30 [95% CI, 1.02-1.65]; grade 2: OR = 1.39 [95% CI, 1.07-1.8]; grade 3: OR = 1.67 [95% CI, 1.23-2.26]; and grade 4: OR = 1.81 [95% CI, 1.00-3.28]) and in Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2 classification (OR = 1.30 [95% CI, 1.03-1.65]) relative to their respective references. The associations observed in these subgroups were consistent regardless of the number of comorbidities per person. Tetrachoric correlations demonstrated negative associations in pairwise comparisons of the top five comorbidities, ranging from -0.03 to -0.31 (p < 0.001 in all groups). Interpretation In China, comorbidities are highly prevalent among patients with COPD, with older age, higher mMRC grade, and lung function decline being the major risk factors. Studies with larger sample sizes are required to elucidate the complex mechanisms underlying COPD comorbidities.