Air pollution exposure and prevalence of non-alcoholic fatty liver disease and related cirrhosis: A systematic review and meta-analysis

Xingyi He; Shipeng Zhang; Qinglin Bai; Moshen Pan; Yanjie Jiang; Weiwei Liu; Wei Li; Yuanyuan Gong; Xueping Li

doi:10.1016/j.ecoenv.2024.117469

Air pollution exposure and prevalence of non-alcoholic fatty liver disease and related cirrhosis: A systematic review and meta-analysis

Ecotoxicol Environ Saf. 2024 Dec 9:289:117469. doi: 10.1016/j.ecoenv.2024.117469. Online ahead of print.

Authors

Xingyi He¹, Shipeng Zhang¹, Qinglin Bai¹, Moshen Pan², Yanjie Jiang³, Weiwei Liu⁴, Wei Li⁵, Yuanyuan Gong⁶, Xueping Li⁷

Affiliations

¹ Hospital of Chengdu University of Traditional Chinese Medicine, Chengdu 610072, PR China.
² School of Economics, Shanghai University of Finance and Economics, Shanghai 200433, PR China.
³ Nanjing Hospital of Chinese Medicine Affiliated to Nanjing University of Chinese Medicine, No.157 Daming Road, Nanjing 210022, PR China.
⁴ School of Basic Medical Sciences, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, PR China.
⁵ Department of Intensive Care Medicine, Sichuan Hospital of Integrated Traditional Chinese and Western Medicine, Chengdu 610041, PR China.
⁶ School of Basic Medical Sciences, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, PR China. Electronic address: gongyuanyuan@cdutcm.edu.cn.
⁷ School of Basic Medical Sciences, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, PR China. Electronic address: jclixueping@cdutcm.edu.cn.

PMID: 39657383
DOI: 10.1016/j.ecoenv.2024.117469

Abstract

Background and objective: A systematic review and meta-analysis were used to investigate the relationship between air pollution exposure and the prevalence of non-alcoholic fatty liver disease (NAFLD) and its related cirrhosis. Through this study, we hope to clarify the potential public health risks of air pollution as an environmental exposure factor.

Methods: Through a comprehensive and systematic search of the EMBASE, PubMed, Web of Science, and Cochrane library databases, studies published up to March 30, 2024, that met the eligibility criteria were identified. The meta-analysis aimed to determine the association between air pollution exposure and NAFLD risk. Subgroup analyses were conducted based on regional economic development after adjusting for confounding factors. The combined odds ratio (OR) was calculated, publication bias was assessed using funnel plots, and consideration was given to heterogeneity among study-specific relative risks.

Results: This review included 14 observational studies (including 7 cohort studies and 7 cross-sectional studies) involving 43,475,41 participants. The pooled analysis showed that PM_2.5, NO_x, PM₁₀, PM_2.5-10, passive smoking, PM₁, and air pollution from solid fuels were positively associated with the incidence and prevalence of NAFLD and its related cirrhosis. The risk ratios for PM_2.5, NO_x, PM₁₀, PM_2.5-10, passive smoking, and air pollution from solid fuels for NAFLD and its related cirrhosis were 1.33 (95 % CI: 1.25, 1.42), 1.19 (95 % CI: 1.14, 1.23), 1.27 (95 % CI: 1.05, 1.55), 1.05 (95 % CI: 1.00, 1.11), 1.53 (95 % CI: 1.12, 2.09), 1.50 (95 % CI: 0.86, 2.63), and 1.18 (95 % CI: 0.85, 1.63), respectively. In contrast, the risk ratio for O₃ was 0.75 (95 % CI: 0.69, 0.83), suggesting that O₃ may lower the incidence and prevalence of NAFLD and its related cirrhosis. We also conducted subgroup analyses based on the level of national development to examine the impact of PM_2.5 on NAFLD and its related cirrhosis. The results showed that the risk of NAFLD and its related cirrhosis associated with PM_2.5 in developing countries was 1.41 (95 % CI: 1.29, 1.53), which was higher than 1.20 (95 % CI: 1.12, 1.29) in developed countries.

Conclusion: The study findings show that PM_2.5, NO_x, PM₁₀, PM_2.5-10, passive smoking, PM₁, and air pollution from solid fuels can increase an individual's risk of developing NAFLD and its related cirrhosis; while O₃ can reduce the risk. In developing countries, the risk level of NAFLD and its related cirrhosis due to PM_2.5 is higher than that in developed countries.

Keywords: Air pollution exposure; Meta-analysis; Non-alcoholic fatty liver disease; Related cirrhosis; Systematic review.