Background Emergency medicine and paediatric hospital medicine physicians each provide a portion of the initial clinical care for the majority of hospitalised children in the USA. While these disciplines share goals to increase quality of care, there are scant data describing their collaboration. Our national, multihospital learning collaborative, which aimed to increase narrow-spectrum antibiotic prescribing for paediatric community-acquired pneumonia, provided an opportunity to examine factors influencing the success of quality improvement efforts across these two clinical departments.

Objective To identify barriers to and facilitators of interdepartmental quality improvement implementation, with a particular focus on increasing narrow-spectrum antibiotic use in the emergency department and inpatient settings for children hospitalised with pneumonia.

Methods We used a mixed-methods design, analysing interviews, written reports and quality measures. To describe hospital characteristics and quality measures, we calculated medians/IQRs for continuous variables, frequencies for categorical variables and Pearson correlation coefficients. We conducted in-depth, semistructured interviews by phone with collaborative site leaders; interviews were transcribed verbatim and, with progress reports, analysed using a general inductive approach.

Results 47 US-based hospitals were included in this analysis. Qualitative analysis of 35 interview transcripts and 142 written reports yielded eight inter-related domains that facilitated successful interdepartmental quality improvement: (1) hospital leadership and support, (2) quality improvement champions, (3) evidence supporting the intervention, (4) national health system influences, (5) collaborative culture, (6) departments’ structure and resources, (7) quality improvement implementation strategies and (8) interdepartmental relationships.

Conclusions The conceptual framework presented here may be used to identify hospitals’ strengths and potential barriers to successful implementation of quality improvement efforts across clinical departments.