Background: Antibiotic use in infants <1 is associated with increased relative risk (~1.5) for childhood asthma in cohort studies. This may be mediated by removal from the infant microbiome of organisms shown to protect against asthma, a hypothesis supported by experiment. We launched this study to see if reductions in antibiotic use at population level are associated with benefit by way of asthma reduction.
Methods: We obtained antibiotic prescribing data from BC PharmaNet, a population-based database that captures all outpatient prescribing for British Columbia, Canada (n=4.7 Million). We focused on prescriptions in children <1 and calculated prescription rate per 1000 population per year. We obtained asthma incidence data from the BC Ministry of Health Chronic Disease Registry. Asthma case identification uses a standard case definition making use of community and hospital diagnostic codes as well as asthma drug data from BCs universal physician billing, hospital and drug databases. We focused on age-stratified asthma incidence for children aged 1-4. The correlation between antibiotic prescription rate in children < 1 and asthma incidence in the following year was estimated using the Spearman test.
Results: Antibiotic prescribing for all age groups fell 9.5% between 1999-2013. The rate for infants < 1 dropped 58% from 1014 to 427 prescriptions per 1000 population/year. Between 2000-2014, asthma incidence (ages 1-4) fell 26% from 27.3 (95%CI: 26.5-28.0) to 20.2 (95%CI: 19.5-20.8) per 1000 population/year. These trends were strongly correlated: Spearmans rho = 0.81 (p=0.0002). The magnitude of fall in asthma incidence is slightly greater than that predicted based on calculated population attributable risk for antibiotic exposure.
Conclusion: The population health benefit from antibiotic stewardship in infants may not be confined to slowing the emergence of resistance and could include a reduced risk of asthma. As this is a population-based ecological study, a reduction in other risk factors may also have contributed to the fall in asthma incidence. This promising trend should be further studied at individual level within a large cohort study.
D. Rasali, None
C. Rose, None
F. Marra, None
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