Effect of Altitude on Respiratory Functional Status in COVID-19 Survivors: Results from a Latin American Cohort-FIRCOV

Laura Gochicoa-Rangel, Santiago C. Maple, Carlos Aguirre-Franco, Wilmer Madrid-Mejia, Monica Gutierrez-Claveria, Lorraine Noriega-Aguirre, Patricia Schonffeldt-Guerrero, Agustin Acuna-Izcaray, Arturo Cortes-Telles, Luisa Martinez-Valdeavellano, Federico Isaac Hernandez-Rocha, Omar Ceballos-Zuñiga, Rodrigo Del Rio Hidalgo, Sonia Sanchez, Erika Meneses-Tamayo, and Ivan Cherrez-Ojeda; and on Behalf of the Respiratory Physiology Project in COVID-19 (FIRCOV). Effect of altitude on respiratory functional status in COVID-19 survivors: results from a Latin American Cohort-FIRCOV. High Alt With Biol XX:XXX-XXX, 2023. Persistent symptoms and lung function abnormalities are common in COVID-19 survivors. Objectives: To determine the effect of altitude and other independent variables on respiratory function in COVID-19 survivors. Methods: Analytical, observational, cross-sectional cohort study done at 13 medical centers in Latin America located at different altitudes above sea level. COVID-19 survivors were invited to perform pulmonary function tests at least 3 weeks after diagnosis. Results: 1,368 participants (59% male) had mild (20%), moderate (59%), and severe (21%) disease. Restriction by spirometry was noted in 32%; diffusing capacity of the lung for carbon monoxide (DLCO) was low in 43.7%; and 22.2% walked less meters during the 6-minute walk test (6-MWT). In multiple linear regression models, higher altitude was associated with better spirometry, DLCO and 6-MWT, but lower oxygen saturation at rest and during exercise. Men were 3 times more likely to have restriction and 5.7 times more likely to have a low DLCO. Those who had required mechanical ventilation had lower DLCO and walked less during the 6-MWT. Conclusions: Men were more likely to have lower lung function than women, even after correcting for disease severity and other factors. Patients living at a higher altitude were more likely to have better spirometric patterns and walked farther but had lower DLCO and oxygen saturation.