1146. Antibiotic Use in Infants Predicts Asthma Rate in Children 1–4 years at Fine Geographic Scale

BACKGROUND: Early-life exposure to antibiotics is associated with childhood asthma. We previously reported that a dramatic drop in infant antibiotic use is correlated with a decline in asthma incidence in children in British Columbia (BC). This study aims to see whether antibiotic exposure predicts asthma at a fine geographic scale after adjustment for known covariates. METHODS: We used prescribing data from BC PharmaNet, a population-based database capturing all outpatient prescribing for BC population (n = 4.7 million). Prescribing rates for infants <1 year were calculated as prescriptions per 1000 population per year using age and sex-specified denominator estimates. Age-adjusted aggregate asthma incidence data for children 1–4 years were obtained from the BC Ministry of Health Chronic Disease Registry. The disease identification uses a standard case definition making using of diagnostic codes (ICD9-493 and ICD10-J45) in BC’s universal hospital and physician billing databases and relevant asthma-specific drug data from BC PharmaNet. We modeled the association between antibiotic prescribing rate and asthma incidence in 91 Local Health Areas using multivariable Poisson regression employing a generalized linear mixed-effects model adjusting for covariates. RESULTS: Between 2000 and 2014, the annual asthma incidence (ages 1–4 years) fell 26% from 27.3 (95% CI: 26.5–28.0) to 20.2 (95% CI: 19.5–20.8) per 1000 population. For children aged 1–4 years in 2000, the average proportion of infants exposed to one or more courses of antibiotics fell from 66.9 to 32.1% over the same interval. Antibiotic was a significant predictor of asthma rate (IRR=1.24 per 10% absolute increase in antibiotic prescribing; 95% CI: 1.19–1.27). Other covariates that remained significant in the model included male sex (IRR=1.56; 95% CI: 1.53–1.58), and atmospheric particulate matter PM 2.5 (IRR=1.08 per interquartile increase; 95% CI: 1.06–1.10). CONCLUSION: Our findings suggest that antibiotic exposure in the first year of life increases the risk of being diagnosed with asthma later in childhood. This is congruent with similar findings at the individual level in a prospective cohort of Canadian children that also points to a pathway through altered gut microbiota. DISCLOSURES: All authors: No reported disclosures.