Wildfire exposure in utero and use of respiratory medications in early childhood
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Background/Aim. Wildfire smoke exposure is a growing concern as wildfires escalate in the western U.S. and abroad (bushfires in Australia). While gestational particulate matter exposure has been linked to increased incidence of childhood respiratory diseases, this association has not been examined with respect to wildfire smoke. Here, we use prescription claims data to investigate the relationship of childhood respiratory illness and in utero exposure to wildfire smoke. Methods. The cohort consisted of infants (N»182,000), born (2010-16) in one of the Metropolitan Statistical Areas (MSAs) of California, Oregon, Washington, Idaho, Nevada, or Montana and followed up to 8 years. We required prescription coverage and estimable birthdates via claims data in IBM’s MarketScan Commercial Claims Database. Our two outcomes were filled prescriptions of ‘upper respiratory’ and ‘lower respiratory’ medications. Using prescription claims, pediatric respiratory drugs (e.g., fluticasone, albuterol) were classified as ‘upper respiratory’ or ‘lower respiratory’ based on active ingredients, mode of administration, and drug class. Wildfire exposure, classified as number of smoke days during each trimester, for each MSA was determined from National Oceanic Atmospheric Association's Hazard Mapping System. First, second, and third trimesters were defined as 280-197, 196-99, and 1-98 days before estimated birthdate, respectively. We used proportional hazards models to assess the relationship of trimester-specific in utero wildfire smoke exposure and first use of respiratory medication. Models are adjusted for sex, birth season, birthyear, meteorological variables, and seasonality. Results. Preliminary results suggest that gestational wildfire smoke is associated with both upper and lower respiratory medication usage during childhood. These associations are modified by season of birth and may differ by birthyear. Sensitivity analyses will account for preterm birth. Conclusion. Our results suggest that incidence of childhood respiratory illness, as indicated by respiratory medication usage, is impacted by in utero exposure to wildfire smoke. This abstract does not necessarily represent EPA policy.