Prevalence of non-smoking chronic obstructive pulmonary disease and its risk factors in China: a systematic review and meta-analysis

Background Chronic obstructive pulmonary disease (COPD) is a prevalent chronic disorder in China, impacting a significant proportion of individuals aged > 40 years. In China, the prevalence of and risk factors for COPD among non-smokers remain largely unexplored. In this study, we aimed to determine the prevalence of COPD in non-smokers within the Chinese population and identify potential risk factors associated with COPD in non-smokers. Methods Web of Science, PubMed, Embase, Chinese WanFang, Chinese China National Knowledge Infrastructure, and Weipu databases from inception to August 5, 2024, were searched. Studies reporting the percentage of never-smokers among those diagnosed with COPD and investigations exploring the risk factors associated with COPD in never-smokers in China were examined. Summary proportions and odds ratios (OR), along with their corresponding 95% confidence intervals (95% CI), were measured. Results In total, 112 investigations with 491,812 participants were included. The percentage of never-smokers in people with COPD was 41.1% (95% CI: 37.5-44.6%). The prevalence of never-smokers among males diagnosed with COPD was 22.3% (95% CI: 18.8-25.7%), which differed from that among women (81.3%, 95% CI: 75.3-87.2%). The results showed an association between the utilization of biomass fuel and the occurrence of COPD in never-smokers (OR: 1.25, 95% CI: 1.06-1.44). Among never-smokers, the data showed a close association between being underweight (OR: 1.89, 95% CI: 1.78-2.00), tuberculosis history (OR: 1.71, 95% CI: 1.53-1.88) and COPD. Never-smokers living in rural areas or those with low educational status were more susceptible to COPD. Conclusion This review confirmed the highly different proportions of never-smokers among male and female patients with COPD. Trial registration PROSPERO: CRD42023420786.