Background: In the United Kingdom, hospital or cancer registry data can be linked to electronic medical records for a subset of general practices and years.
Methods: We used Clinical Practice Research Datalink data (2004-2012) from patients treated for overactive bladder. We electronically identified provisional cases of 10 common cancers in General Practitioner Online Database data and validated them by medical profile review. In practices with linkage to Hospital Episodes Statistics and National Cancer Data Repository (2004-2010), we validated provisional cancer cases against these data sources. This linkage also let us identify additional cancer diagnoses in individuals without cancer diagnosis records in the General Practitioner Online Database.
Results: Among 50,840 patients, 1,486 provisional cancer cases were identified in the General Practitioner Online Database for 2004-2012. Medical profile review confirmed 93% of 661 cases in nonlinked practices (range, 100% of non-Hodgkin lymphomas and uterine cancer to 77% of skin melanomas) and 96% of 825 cases in linked practices (100% of kidney and uterine cancers to 92% of melanomas). In the subset of linked practices, for 2004-2010, 720 cases were confirmed, of which 68% were identifiable in the General Practitioner Online Database (range, 90% of breast to 36% of kidney cancers).
Conclusions: Most cases of cancer identified electronically in the General Practitioner Online Database were confirmed. A substantial proportion of cases, especially of cancer types not typically managed by general practitioners, would be missed without Hospital Episodes Statistics and National Cancer Data Repository data (and are likely missed in nonlinked practices). See video abstract at, http://links.lww.com/EDE/B315.
Registration (before study conduct): European Union electronic Register of Post-Authorisation Studies (EU PAS Registry) number EUPAS5529, http://www.encepp.eu/encepp/viewResource.htm?id=11107.