The “Slow Horse Racing Effect” on Lung Function in Adult Life in Chronic Obstructive Pulmonary Disease Associated to Biomass Exposure

Abstract

Although different trajectories in lung function decline have been identified in patients with COPD associated to tobacco exposure (TE-COPD), genetic, environmental, and infectious factors affecting lung function throughout life have not been fully elucidated in patients with COPD associated to biomass (BE-COPD). In this review, we present current epidemiological findings and notable advances in the natural history of lung decline in BE-COPD, as well as conditions modeling the FEV1 trajectory, such as health insults, during the first years of childhood. Evidence shows that women exposed to biomass smoke reach adult life with a lower FEV1 than expected. However, in contrast to the “horse racing effect” predicting an excessive lung-function decline in forthcoming years, as observed in smokers, this decline is slower in non-smokers, and no rapid decliners are observed. Accordingly, BE-COPD might be considered another phenotype of COPD based on assessments of lung function decline. Likewise, other functional and clinical aspects described in this review suggest that this condition might be similar to TE-COPD. More research is needed to fully characterize this subgroup of variants of COPD.

Global Initiative for Chronic Obstructive Lung Disease 2023 Report: GOLD Executive Summary

“…They have similar spirometric indices but greater small airway obstruction, less emphysema, and a lesser rate of lung function decline. Finally, they show lower neutrophil count, higher eosinophil numbers in the sputum ( 13 ), and a similar defect in macrophage phagocytosis of pathogenic bacteria ( 17 ). Research is needed to understand how interventions aimed at decreasing household air pollution can reduce the risk of COPD as well as what is the most appropriate pharmacotherapy for this type of COPD ( 13 ).…”

Global Initiative for Chronic Obstructive Lung Disease 2023 Report: GOLD Executive Summary

“…They have similar spirometric indices but greater small airways obstruction, less emphysema and lesser rate of lung function decline. Finally they show lower neutrophil count, higher eosinophil numbers in the sputum (13) and a similar defect in macrophage phagocytosis of pathogenic bacteria (17). Research is needed to understand how interventions aimed at decreasing household air pollution can reduce the risk of COPD as well as what is the most appropriate pharmacotherapy for this type of COPD (13).…”

Characteristics of patients with chronic airflow obstruction caused by solid fuel or tobacco smoke

“…[ 4 ] The authors only included participants aged ≥ 40 years, but CAO associated with solid fuel smoke could be prevalent in younger people. Recently, Ramírez-Venegas et al [ 5 ] suggested that participants exposed to solid fuel smoke reach adult life with a lower FEV 1 level and normal decline of lung function, whereas participants exposed to tobacco smoke with a rapid decline in FEV 1 from a normal level of lung function. Therefore, we need more longitudinal studies to verify this conclusion.…”