High COPD prevalence at high altitude:does household air pollution play a role?

Studies comparing COPD prevalence across altitudes report conflicting results. Yet, household air pollution, a major COPD risk factor, was mostly not accounted for in previous analyses and never objectively measured. We aimed to compare the prevalence of COPD and its risk factors between low-resource highlands and lowlands, with a particular focus on objectively-measured household air pollution.We conducted a population-based, observational study in a highland (∼2050 m) and lowland (∼750 m) setting in rural Kyrgyzstan. We performed spirometry in randomly selected households, measured indoor particulate matter <2.5 µm (PM2.5), and administered a questionnaire on other COPD risk factors. Descriptive statistics and multivariable logistic regressions were used for analyses.We included 392 participants: 199 highlanders and 193 lowlanders. COPD was more prevalent among highlanders (36.7% versus 10.4%, p<0.001). Also, their average PM2.5-exposure was higher (290.0 versus 72.0 µg·m-3, p<0.001). Besides high PM2.5-exposure (OR 3.174; 95% CI 1.061-9.493), the altitude setting (3.406; 1.483-7.825), pack years (1.037; 1.005-1.070), and age (1.058; 1.037-1.079) also contributed to a higher COPD prevalence among highlanders.COPD prevalence and household air pollution were highest in the highlands and were independently associated. Preventive interventions seem warranted in these low-resource, highland settings. With this study being one of the first spirometry-based prevalence studies in Central-Asia, generalisability needs to be assessed.