Early-life liquefied petroleum gas cooking intervention and lung function in Guatemalan children: A randomized clinical trial

RATIONALE: Household air pollution is a risk factor for obstructive lung diseases. OBJECTIVES: We estimated the effect of an early-life liquefied petroleum gas cooking intervention on childhood lung function. METHODS: The multi-country Household Air Pollution Intervention Network trial randomized 800 pregnant women (9-19 weeks gestation, 18-34 years) in Guatemala to receive a gas cookstove and free fuel intervention or continue cooking with biomass until the child is aged 1 year. The present analysis includes only Guatemalan children. At age 3 years, we measured lung function using oscillometry at 7-41 Hertz (Tremoflo C-100, Thorasys). Outcomes were resistance and reactance at 7 Hertz, area of reactance, resistance at 19 Hertz, resistance difference between 7 and 19 Hertz, and, as exploration, resistance across frequencies. Upper airway artifacts were removed using Tremoflo software. The effect of the intervention was estimated using linear regression models, unadjusted and adjusted (height, weight, age, sex). Children with respiratory infections during a 7-day recall period were excluded. RESULTS: Valid oscillometry was obtained from 525/750 (70%) 3-year-olds. Among the 225 missed oscillometry tests, 129/750 (17%) were due to the children not being willing to perform the measurements. We did not find evidence of an effect on prespecified oscillometry outcomes. Exploratory analysis suggested that resistance across the frequency spectrum was lower in intervention than control participants (adjusted difference: -0.31 cmH2O*S/L, 95% CI: -0.59, -0.03). CONCLUSIONS: Gas cooking compared to biomass cooking from mid-gestation through infancy was not associated with improved prespecified oscillometry outcomes in 3-year-old children. However, lowered resistance across all frequencies in the intervention arm suggests the intervention may have positively impacted airway caliber. Further studies are warranted, including exposure-response analysis and lung function trajectories.