Spirometry at different Latin American altitudes: a Global Lung Function Initiative project

Approximately 20% of people in Latin America live more than 2500 m above sea level. In this ethnically and socioeconomically diverse population, it is challenging to differentiate the effects of altitude from population differences in lung function. The aim of the present study was to quantify the contribution of altitude on the variability in lung function measured by spirometry in Latin America.

Data from healthy individuals living in nine cities across Latin America (from sea level to >2500 m above sea level) were collated. Z-scores for forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC) and FEV₁/FVC were calculated using available reference equations. Mixed-effects linear regression models were used to quantify the variance in spirometry explained by altitude. The percentage of individuals that were below the lower limit of normal (fifth percentile) were summarised.

A total 4480 subjects (3-94 years) were included. Average FEV₁ and FVC z-scores differed between the altitude groups, whereas FEV₁/FVC did not. After adjusting for sex, height and age, altitude explained up to ∼18% of the variability in lung function measured by spirometry.

For people living at altitude, existing approaches to interpreting spirometry measures may misclassify individuals.