Effects of a randomized biomass cookstove intervention on glycated hemoglobin among women in Honduras

Abstract

AIM: Using a stepped-wedge randomized controlled trial, we evaluated impacts of the wood-burning Justa cookstove (engineered combustion chamber, chimney) on glycated hemoglobin (HbA1c) among rural Honduran women. METHODS: We enrolled 230 cooks who were not pregnant, non-smoking, aged 24-59 years, and using a traditional stove. There were 6 study visits per participant, separated by 6 months. Participants were randomized to receive the Justa after 2 visits (Arm 1) or after 4 visits (Arm 2). We measured personal and kitchen 24-hour gravimetric fine particulate matter (PM2.5) and finger-stick HbA1c at each visit. We used linear mixed models adjusted for time and other covariates in intent-to-treat (assigned stove) and exposure-response (estimates per 1-unit higher log-transformed PM2.5) analyses. Sensitivity analyses included: limiting to the first 4 visits to approximate a parallel-trial design and, given large within-person variability in PM2.5 across visits, using geometric mean PM2.5 by assigned stove status for each participant as the exposure-of-interest. RESULTS: Among 227 women with 1,208 observations, Justa stove use reduced median (25th, 75th percentiles) personal PM2.5 concentrations (traditional: 82 µg/m3 [50, 142]; Justa: 43 µg/m3 [27, 73]). Participants had non-significantly reduced HbA1c when using Justa compared to traditional stoves (-0.06%, 95% CI: -0.16, 0.04). No associations were observed between personal and kitchen PM2.5 and HbA1c (0.01%, 95% CI: -0.03, 0.04; 0.02%, 95% CI: -0.01, 0.05; respectively). In sensitivity analyses limited to visits 1-4, a reduction in HbA1c was observed for Justa use compared to traditional stove use (-0.10%, 95% CI: -0.18, -0.01). Geometric mean personal and kitchen PM2.5 exposures were associated with HbA1c (0.03%, 95% CI: -0.03, 0.09; 0.04%, 95% CI: 0.001, 0.08, respectively). CONCLUSIONS: The Justa intervention reduced PM2.5 concentrations, but wide confidence intervals limit interpretations of HbA1c changes in primary analyses. Potentially relevant benefits were observed in sensitivity analyses and will be explored further.