A cluster randomised trial of cookstove interventions to improve infant health in Ghana

Abstract

Introduction: Household air pollution from solid fuel combustion for cooking and heating is a leading cause of childhood morbidity and mortality worldwide. We hypothesised that clean cooking interventions delivered during pregnancy would improve child health.

Methods: We conducted a cluster randomised trial in rural Ghana to test whether providing pregnant women liquefied petroleum gas (LPG) cookstoves or improved biomass cookstoves would reduce personal carbon monoxide and fine particulate pollution exposure, increase birth weight and reduce physician-assessed severe pneumonia in the first 12 months of life, compared with control participants who continued to cook with traditional stoves. Primary analyses were intention-to-treat. The trial was registered with ClinicalTrials.gov and follow-up is complete.

Results: Enrolment began on 14 April 2014, and ended on 20 August 2015. We enrolled 1414 pregnant women; 361 in the LPG arm, 527 in the improved biomass cookstove arm and 526 controls. We saw no improvement in birth weight (the difference in mean birth weight for LPG arm births was 29 g lighter (95% CI -113 to 56, p=0.51) and for improved biomass arm births was 9 g heavier (95% CI -64 to 82, p=0.81), compared with control newborns) nor severe child pneumonia (the rate ratio for pneumonia in the LPG arm was 0.98 (95% CI 0.58 to 1.70; p=0.95) and for the improved biomass arm was 1.21 (95% CI 0.78 to 1.90; p=0.52), compared with the control arm). Air pollution exposures in the LPG arm remained above WHO health-based targets (LPG median particulate matter less than 2.5 microns in diameter (PM_2.5) 45 µg/m³; IQR 32-65 vs control median PM_2.5 67 µg/m³, IQR 46-97).

Conclusions: Neither prenatally-introduced LPG nor improved biomass cookstoves improved birth weight or reduced severe pneumonia risk in the first 12 months of life. We hypothesise that this is due to lower-than-expected exposure reductions in the intervention arms.

Trial registration number: NCT01335490.

Keywords: child health; environmental health; epidemiology; randomised control trial.

Figure 1

Trial profile. *Deaths of children at age >7 days who did not have any recorded fieldworker follow-up. LPG, liquefied petroleum gas.

Figure 2

Time to first event of: (A) Physician-diagnosed pneumonia; (B) physician-diagnosed severe pneumonia; (C) combined physician-diagnosed and fieldworker-diagnosed pneumonia; and (D) combined physician-diagnosed and fieldworker-diagnosed pneumonia by control, improved biomass or liquefied petroleum gas (LPG) cookstove study arm. Cox proportional-hazard models adjusting for asset index, month of delivery, child sex and child age demonstrated no difference in groups regardless of pneumonia outcome considered.

Figure 3

The distribution of maternal personal fine particulate matter (PM_2.5) exposure during the GRAPHS post-intervention period. Violin plots show the density of air pollution exposures, boxplots show the median and IQR, the mean exposure is shown with black diamonds for each study arm and partially transparent dots show all 48-hour estimates. The dotted line represents the WHO interim-1 guideline for annual PM_2.5 exposure (35 μg/m³) and solid line is the WHO guideline for annual PM_2.5 exposure (10 μg/m³). In the control arm, 174 women had one PM_2.5 exposure estimate, 145 had two exposure estimates and 37 had three or more exposure estimates. In the improved biomass arm, 178 women had one PM_2.5 exposure estimate, 106 had two exposure estimates and 37 had three or more exposure estimates. In the liquefied petroleum gas (LPG) arm, 125 women had one PM_2.5 exposure estimate, 59 had two exposure estimates and 18 had three or more exposure estimates. All estimates, including multiple observations per participant, are plotted and contribute equally to summary statistics. Summary statistics ‘mean±SD’ and ‘median (IQR)’ are 48-hour PM_2.5 concentration estimates with units μg/m³. GRAPHS, Ghana Randomized Air Pollution and Health Study; PM_2.5, particulate matter less than 2.5 microns in diameter.