Extended antibiotic exposure and exacerbations, mortality, and healthcare costs in asthma

Asthma exacerbations contribute significantly to morbidity, mortality, and healthcare costs, with antibiotics commonly prescribed despite uncertain benefits and risks. This retrospective cohort study analyzed claim database between 2020 and 2022. Patients were categorized into extended (≥ 4 weeks) or limited (< 4 weeks) antibiotic exposure groups based on cumulative antibiotic use. We assessed the associations between prior antibiotic exposure and moderate-to-severe exacerbations, all-cause mortality, and total healthcare costs. We identified 549,425 adult asthma patients, classified into extended (25.2%) and limited (74.8%) antibiotic exposure groups. Extended antibiotic exposure was significantly associated with moderate-to-severe exacerbations (aOR = 1.25, 95% CI = 1.23-1.26) and nearly doubled the odds of all-cause mortality (aOR = 1.99, 95% CI = 1.92-2.07). Patients in the extended exposure group incurred significantly higher healthcare costs (median 7,433 vs. 5,471 thousand KRW, P < 0.001). A cumulative association pattern was observed, where longer durations of antibiotic use, greater cumulative doses, and exposure to multiple antibiotic classes were associated with progressively greater odds of exacerbations, mortality, and increased medical costs. Significant interactions revealed that rhinitis and sinusitis mitigated attenuated these associations, while bronchiectasis further strengthened them. Extended antibiotic use in adult asthma patients was linked to worse outcomes. However, as causality cannot be confirmed due to potential biases, further studies are needed.