Linking individual-level data on diagnoses and dispensing for research on antibiotic use: Evaluation of a novel data source from English secondary care

There has been a focus on stewardship programmes to curb inappropriate antibiotic prescribing and reduce antimicrobial resistance. In-hospital, patient-level prescribing linked to indication is needed to support surveillance, evaluation of stewardship initiatives, as well as other antibiotic research. We evaluated whether a novel dataset linking hospital pharmacy records to Hospital Episode Statistics data can be used for antibiotic research.

Using the Hospital Treatment Insights (HTI) database, which links Hospital Episode Statistics to pharmacy records from 43 out of 153 hospital trusts in England, we estimated the proportion of missed linkage and identified characteristics associated with missing data.

Linkage of antibiotics to patients was inconsistent and dependent on drug type and clinical setting, so that linkage for some specific antibiotics was high (80-100%), but overall, only 27.6% (CI: 27.4%-27.8%) for all antibiotics dispensed. Linkage was best for quinolones (62.6%; CI: 61.8%-63.8%), but only 21.1% (CI: 21.1%-21.2%) for penicillins. Linkage was lower for common antibiotics and in emergency departments; however, 80% linkage was achieved for individual drugs like clindamycin, especially on wards with reduced ward stock use.

For those antibiotics with high linkage, HTI might be used to study associations between indication, dispensing, and outcomes. However, the majority of common antibiotics had insufficient linkage, likely due to extensive use of ward stocks. Therefore, HTI in its current form is not suitable for general antibiotic surveillance or evaluation of stewardship initiatives. For drugs in HTI other than antibiotics, linkage should be similarly evaluated before a study is conducted.