Impact of quality clusters on antibiotic prescribing patterns. A difference-in-differences study from Danish general practice

Globally, a more rational use of antibiotics is needed to face the threat of antimicrobial resistance. In 2018, quality clusters were introduced in Danish general practice as a new quality improvement initiative. In the clusters, general practitioners engage in self-selected quality improvement topics, such as antibiotics prescribing. This study investigates whether engaging with antibiotics as a topic in quality clusters improves antibiotics prescribing, and whether choice and number of quality improvement strategies matter for behaviour change. We link register data on redeemed antibiotics prescriptions from Danish general practice from 2015-2020 with survey data from 2020 on whether, when, and how practices in clusters engaged with antibiotics as a quality improvement topic. We use a difference-in-differences approach including general practice fixed effects and practice-averaged time-varying patient population characteristics in linear regressions models. We find that practices engaged with antibiotics as a quality improvement topic increase their proportion of narrow spectrum antibiotics prescriptions compared to other practices, while there is no difference in changes in the total number of prescribed antibiotics. Neither the choice nor the number of surveyed quality improvement strategies seem to influence the behavioural outcomes. In conclusion, engaging in antibiotics in quality clusters to some extent improved antibiotic prescribing.