Documentation of penicillin adverse drug reactions in electronic health records: inconsistent use of allergy and intolerance labels

Background: The majority of patients with penicillin allergy labels tolerate penicillins. Inappropriate avoidance of penicillin is associated with increased hospitalisation, infections and healthcare costs. 

Aims: To examine the documentation of penicillin adverse drug reactions (ADR) in a large-scale hospital-based electronic health record. 

Methods: Penicillin ADR were extracted from 96 708 patient records in the Enterprise Patient Administration System in South Australia. Expert criteria were used to determine consistency of ADR entry and suitability for further evaluation. 

Results: Of 43 011 unique ADR reports, there were 5023 ADR to penicillins with most being entered as allergy (n = 4773, 95.0%) rather than intolerance (n = 250, 5.0%). A significant proportion did not include a reaction description (n = 1052, 20.9%). Using pre-set criteria, 10.1% of reports entered as allergy had a reaction description that was consistent with intolerance and 31.0% of the entered intolerances had descriptions consistent with allergy. Virtually all ADR (n = 4979, 99.1%) were appropriate for further evaluation by history taking or immunological testing and half (50.7%, n = 2549) had documented reactions suggesting low-risk of penicillin allergy. 

Conclusion: The frequency of penicillin allergy label in this data set is consistent with the known overdiagnosis of penicillin allergy in the hospital population. ADR documentation was poor with incomplete entries and inconsistent categorisation. The concepts of allergy and intolerance for ADR classification, whilst mechanistically valid, may not be useful at the point of ADR entry by generalist clinicians. Systematic evaluation of reported ADR is needed to improve the quality of information for future prescribers.