Opioid Allergy Registrations in Danish Electronic Health Records: A Multihospital Register-Based Study With Journal Audit.

Accurate documentation of drug allergies is critical to prevent re-exposure while avoiding unnecessary restrictions on safe pharmacotherapy. Although true opioid hypersensitivity is rare, adverse effects are frequently misclassified as allergies. The aim of the present study was to evaluate opioid allergy registration across six Danish hospitals. All opioid allergy registrations between 2020 and 2023 were analysed using text-mining algorithms. Registrations were dichotomised as 'probable allergy' or 'not allergy' based on predefined keywords and validated by manual journal audit. Among 1 199 314 patients, there were 14 661 allergy registrations towards an opioid. Only 19% (n = 2710) of the allergy registrations were classified as probable allergies, predominantly driven by rash and/or pruritus (71%). The likelihood of an allergy registration being 'probable' was universally low, although slightly higher for intravenously administered opioids compared with orally administered morphine (OR = 0.26, 95% CI: 0.21; 0.32) and tramadol (OR = 0.36, 95% CI: 0.25; 0.46). The audit of 203 allergy registrations corroborated the text-mining results. Notably, 63 patients (33%) received the same opioid despite a registered allergy. Opioid allergy registrations frequently misrepresent expected adverse drug reactions as true hypersensitivity, particularly for oral formulations. Improved diagnostic differentiation and documentation accuracy are imperative to optimise patient pain management protocols in hospitals.