Assessing markers of data quality in routinely-collected primary care data

Routinely-collected primary care data are widely used for research. However, clinical recording likely varies between GP practices. It is therefore important that researchers consider practice-level data quality and, if necessary, take steps to exclude data of insufficient quality. One approach is to assign each practice an ‘up-to-standard’ (UTS) date after which its data is considered acceptable for research. This study will propose a methodology for deriving practice UTS dates in routinely-collected primary care data. Our methodology will be developed on a sample extracted from CPRD Aurum for the purpose of examining risk of cancer or symptomatically-similar diseases in patients presenting in primary care. We will consider four components likely to reflect practice-level data quality: the registration of new patients, and the recording of observations, consultations, and deaths. Researchers experienced in primary care data analysis will review time series of practice-level metrics based on these components for a random sample of 30 practices. This will inform the development of criteria to determine up-to-standard dates. These criteria will then be applied to the full extract to