Exposure to indoor wood smoke, rather than hypoxemia, is a risk factor for cognitive impairment in COPD patients living at high altitude

BackgroundIn the general population without COPD, indoor air pollution from biomass is a causal factor of cognitive impairment (CI). CI is also common in patients with tobacco smoke COPD and has been associated with hypoxemia and cardiovascular comorbidities. CI and its risk factors have not been evaluated in COPD patients living at high altitude, who experience greater hypoxemia and frequent exposure to wood smoke.MethodsPatients with COPD residing at high altitude with FEV1/FVC <0,70 and COPD risk factors (wood smoke, Tobacco smoke or combined exposure). Measurement of the Mini-Mental State Examination to assess CI, educational level, comorbidities, exacerbations, arterial blood gases, diffusion (DLCO), and 6-min walk test (6MWT). Comparisons between groups with and without CI using the X2 test and unpaired t-test. Logistic regression with odds ratio (OR) calculation was used to evaluate the association of CI with the variables of interest.ResultsIn the 199 patients included, 16.1% had CI, the majority with mild involvement (68.8%). Those with CI had more frequent exposure to wood smoke (p<0.001), older age (p=0.017), lower educational level, PaO2 (p=0.032), DLCO (p=0.036), and fewer meters in the 6MWT (p=0.007), with no differences in sex, severity of obstruction or comorbidities. Adjusting for the other variables, exposure to wood smoke was associated with CI [OR and 95% CI: 4.82 (1.62-14.33).ConclusionsIn patients with mild to moderate COPD living at high altitude, regardless of hypoxemia, age, educational level, comorbidities, and lung function, exposure to wood smoke was associated with CI.