A Letter From the CMO in England to Reduce Antibiotic Prescribing in General Practice: A Randomized Controlled Trial Comparing Monitoring and Feedback (With and Without Graphs), and Social Norms Feedback (Without and Without a Specific Case Study of Patient Harm)

This trial aims to reduce inappropriate prescription of antibiotics and broad spectrum antibiotics by general practitioners (GPs) in England. Unnecessary prescriptions are defined as those that do not improve patient health outcomes. The intervention is to send GPs a letter from the Chief Medical Officer (CMO) that gives feedback on their practice's prescribing levels.

There will be three intervention samples:

1. practices whose prescribing in the past year was under the new target of 0.965 items per STAR-PU but who would exceed the target if they had a 5% increase in prescribing; trial compares prescribing of practices whose GPs receive a letter informing them that their practice's prescribing is just under the new target to that of practices that are not sent a letter
2. Practices whose prescribing in the past year was above the new target but who not in the top 20% of prescribers; trial compares prescribing of practices whose GPs receive a letter informing them that their practice's prescribing exceeds the new target to practices who get a letter that includes a graph showing their prescribing relative to the target and to practices that are not sent a letter
3. Practices that are currently in the top 20% of prescribers; trial compares effect on prescribing of a feedback letter with a social norms message (current standard practice for this group) to a letter informing GPs that their practice's prescribing exceeds the new target and to a letter with a social norms message, that includes a specific example of a case of patient harm caused by antimicrobial resistance.