Wildfire smoke exposure and early childhood respiratory health: a study of prescription claims data
Rationale & Objectives: Wildfire smoke is associated with short-term respiratory outcomes including asthma exacerbation in children. As investigations into developmental exposure to wildfire smoke exposure (WSE) on children’s longer-term respiratory health are sparse, we investigated associations between developmental WSE and first use of respiratory medications. Methods: Prescription claims from IBM MarketScan Commercial Claims and Encounters database were linked with wildfire smoke plume data from NASA satellites based on Metropolitan Statistical Area (MSA). A retrospective cohort of live infants (2010-2016) born into MSAs in six western states, having prescription insurance, and whose birthdate was estimable from claims data was constructed (N=184,703); of these, gestational age was estimated for 113,154 infants. MSA, gestational age, and birthdate were used to estimate average weekly smoke exposure days (smoke-day) for each developmental period: three trimesters, and two sequential 12-week periods post-birth. Medications treating respiratory tract inflammation were classified using active ingredient and mode of administration into three categories: ‘upper respiratory’, ‘lower respiratory’, ‘systemic anti-inflammatory’. To evaluate associations between WSE and medication usage, Cox models associating smoke-days with first observed prescription of each medication category were adjusted for infant sex, birth-season, and birthyear with a random intercept for MSA. Results: Smoke exposure during postnatal periods was associated with earlier first use of upper respiratory medications (1-12 weeks: hazard ratio (HR)=1.094 per average weekly smoke-day, 95%CI: (1.005,1.191); 13-24 weeks: HR=1.108, 95%CI: (1.016,1.209)); sex-specific HRs varied by post-birth exposure window. Conclusion: These findings suggest that WSE during early postnatal developmental periods impact subsequent early life respiratory health.