CPRD Aurum database: Assessment of data quality and completeness of three important comorbidities.

Our findings indicate that for studies of type 2 diabetes, hyperlipidemia, and iron deficiency or unspecified anemia, the diagnosis code is likely to be correct where present. However, a significant proportion of cases of hyperlipidemia or anemia will be missed if only diagnosis codes are used to select patients with these conditions. Researchers should consider using treatments, supporting codes, and, when available, lab data to supplement diagnosis codes and enhance case capture when including these conditions in studies using CPRD Aurum.