Thorax 2009;64(Suppl IV):A75–A174, doi:10.1136/thx.2009.127191g
COPD AND CHRONIC BRONCHITIS RISK OF SOLID FUEL SMOKE: A SYSTEMATIC REVIEW AND META-ANALYSIS
1-O Kurmi, 2-S Semple, 2-PP Simkhada, 2-WCS Smith, 1JG Ayres. 1University of Birmingham, Birmingham, UK; 2University of Aberdeen, Aberdeen, UK
Introduction and Objectives – Over half the world is exposed daily to the smoke from combustion of solid fuels. Chronic obstructive pulmonary disease (COPD) is one of the main contributors to the global burden of disease and can be caused by biomass smoke exposure. However, studies of biomass exposure and COPD show a wide range of effect sizes. The aim of this systematic review was to quantify the impact of biomass smoke on the development of COPD and define reasons for differences in the reported effect sizes.
Methods – A systematic review was conducted of studies with sufficient statistical power to estimate the risk of COPD from exposure to solid fuel smoke which followed standardised criteria for the diagnosis of COPD, adjusted for smoking, were in English and contained original data. The results were pooled by fuel type and country to produce summary estimates using a random effects model. Publication bias was also estimated.
Results – 4164 titles were identified which were reduced to 24 studies (11 relating to COPD, 11 to chronic bronchitis and 2 to both). Pooled estimates for the development of COPD with solid fuel use showed an odds ratio of 2.66 (95% CI 1.81 to 3.92) (fig 1) and an OR of 2.32 (95% CI 1.92 to 2.80) for chronic bronchitis. Pooled estimates by fuel type showed that exposure to wood smoke presents a greater risk of development of COPD (wood: OR 4.3; mixed biomass: OR 2.8). The findings for chronic bronchitis were similar. There was no evidence of publication bias but there was clear variation between studies which might be explained by study design, dealing with confounders, use of selected comparator groups or exposure assessment, although differential toxicity of different fuels is the most likely explanation.
Conclusion – Despite heterogeneity across the selected studies, exposure to solid fuel smoke is consistently associated with COPD and chronic bronchitis. Efforts should be made to reduce exposure to solid fuel either by using cleaner fuel or relatively cleaner technology while performing domestic work.
