The prescribing safety indicators are rated by risk of harm to the patient and only indicators rated 4 (extreme risk of harm) or 3 (high risk of harm) were considered for inclusion.

CPRD researchers reviewed the subset of indicators thus shortlisted to identify which ones were likely to be recorded well in the CPRD primary care data.

Initial searches were conducted in the CPRD data to ascertain the number of patients that would be identified for the indicators under consideration; indicators affecting the highest number of affected patients were prioritised.

Indicators needed to identify safety events that were common enough to report on for most practices, but not so common as to make patient review unmanageable for GP workload.

The MHRA was consulted to ensure that the QI reports did not include any prescribing indicators for drugs that were being actively monitored as part of the MHRA Patient Safety Alert effectiveness monitoring to avoid biasing their findings.