• evaluation methodology
• healthcare quality improvement
• implementation science
• quality improvement

The study by DiDiodato and McAthur1 describes work to improve the care of patients admitted to hospital with community-acquired pneumonia. They compare length of stay of patients after the implementation of an antimicrobial stewardship programme that was initially led by an infectious disease-trained pharmacist and then transitioned to a ward-based pharmacist. To estimate the impact on length of stay, they used a stepped-wedge design, where the transition to a ward-based pharmacist in four medical wards was staggered in 2 monthly intervals over an 8-month period. This quasi-experimental approach allowed the investigators to create reasonable comparator groups and meant that all wards eventually received the intervention. Consequently, DiDidato and colleagues provided a compelling estimate of the impact of transitioning to a ward-based pharmacist indicating a 19.4% relative reduction in length of stay for patients admitted with community-acquired pneumonia. Such efforts to design improvement work in a way that allows an estimate of the impact relative to a comparison group remain uncommon in the published improvement field. DiDiodato and colleagues should …