Abstract 2297: Household stove improvement and risk of chronic obstructive pulmonary disease in Xuanwei, China: a cohort study
Authors: Zhang Jinming , Bassig Bryan A. , Vermeulen Roel , Seow Wei Jie , Wong Jason Y.Y. , Hu Wei , Ning Bofu , Downward George S. , Katki Hormuzd A. , Ji Bu-Tian , Rothman Nathaniel , Chapman Robert S. , Lan Qing 
Published: July 2017

Abstract
Background: In Xuanwei County, China, chronic obstructive pulmonary disease (COPD) rates are over twice the national average. Patients with COPD have higher risks of both lung cancer and poor treatment outcomes after lung cancer diagnosis. In a prior retrospective cohort study (1976-1992), household stove improvement was found to be associated with decreased COPD incidence among lifetime smoky (bituminous) coal users. However, whether the protective effects persist over time is unclear. Our objective was to evaluate the associations between risk of COPD, and vented and portable stove use with extended follow-up (1976-2011).
Methods: The study population comprised 22,833 residents who were born between 1917 and 1951 and lived in Xuanwei as of January 1, 1976. Participants were followed retrospectively from 1976 to 1992, and then followed prospectively through 2011. We conducted two surveys in 1992 and 2011. During each survey, we collected comprehensive information on household stove type, fuel use, family size and number of rooms in each residence during the lifetime, smoking, education, age started cooking food and time spent indoor from each subject. Participants were also asked to report any medically diagnosed chronic bronchitis or emphysema, age and place of diagnosis, which we combined into a single category of COPD. COPD cases diagnosed before January 1, 1976 were excluded. Sex-specific time-dependent Cox regression models were used to estimate the hazard ratio (HR) of stove improvement for COPD incidence among lifetime smoky coal users.
Results: The analysis was restricted to lifetime smoky coal users. A significant reduction in COPD incidence was found after change to vented stoves (Men’s model: HR=0.66, 95% confidence interval(CI): 0.59-0.75; Women’s model: HR=0.63, 95% CI: 0.55-0.72) and portable stoves (Men’s model: HR=0.77, 95% CI: 0.67-0.88; Women’s model: HR=0.63, 95% CI: 0.54-0.74). There was a downward trend of COPD incidence over time after change to vented stove or portable stove (p-trend&lt;0.01). Similar findings were noted in both men and women.
Conclusion: Consistent with prior research, our findings suggest that household stove improvement was associated with a substantially decreased risk of COPD, a strong risk factor for lung cancer. Domestic smoky coal use and unvented coal combustion are important risk factors for COPD. Our findings support the need for replacing smoky coal with less carcinogenic fuels in areas where domestic coal use is common for cooking and heating, especially in the developing countries.
Citation Format: Jinming Zhang, Bryan A. Bassig, Roel Vermeulen, Wei Jie Seow, Jason Y.Y. Wong, Wei Hu, Bofu Ning, George S. Downward, Hormuzd A. Katki, Bu-Tian Ji, Nathaniel Rothman, Robert S. Chapman, Qing Lan. Household stove improvement and risk of chronic obstructive pulmonary disease in Xuanwei, China: a cohort study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2297. doi:10.1158/1538-7445.AM2017-2297