Objective: To identify factors that influence providers' decisions to prescribe antibiotics in patients presenting to the hospital with an asthma exacerbation. Methods: We performed semi-structured interviews with a purposive sample of providers including sixteen hospitalists, emergency room providers, or pulmonologists, and one focus group with internal medicine residents recruited from one large, urban, teaching hospital and one small, rural, community hospital. Questions were informed by the Theoretical Domains Framework to determine factors that may influence behaviors. Directed content analysis was used to code and analyze transcripts of the interviews. Results: Uncertainty regarding the diagnostic (asthma vs. COPD) and the cause of exacerbation (bacterial vs. viral infection) emerged as the main driver for prescribing behavior. Provider response to uncertainty included: "watchful waiting" or immediate antibiotic prescribing. The following factors played important roles in providers' prescribing decision: 1) awareness/agreement with existing guidelines 2) confidence in their ability to apply the guidelines in challenging cases; 3) perceived risk of patient deterioration without antibiotics; 4) fear of litigation; 5) habit and clinical inertia 6) prescribing within the group 7) lack of information of antibiotic prescribing rates and 8) lack of time and/or resources. Conclusions: We identified diagnostic uncertainty as the primary determinant of antibiotic prescribing in asthma exacerbations and developed a conceptual model to explain provider responses and factors that influenced their responses. These results enhance our understanding of the factors that can contribute to low-value and wasteful practices like superfluous antibiotic prescribing and will support the development of interventions to de-implement such practices.

Keywords: Uncertainty; antibiotics; asthma; behavior; de-implement; exacerbation; guidelines; interviews; model; qualitative; semi-structured.