None listed
Conditions
Brief summary
Pholcodine is an over-the-counter cough medicine that may increase the risk of severe allergic reactions to neuromuscular blocking agents (NMBAs) used during anaesthesia. In March 2023, all pholcodine-containing cough products were withdrawn from the Australian market. This study will use a prospectively approved and maintained Western Australian perioperative allergy registry to examine whether the withdrawal was followed by changes in the number of clinically investigated allergic reactions attributed to NMBAs, compared with reactions attributed to other drugs. Monthly counts of reactions from January 2016 to November 2025 will be analysed using interrupted time-series regression, focusing on level and trend changes at the time of the pholcodine withdrawal. No additional procedures, tests or changes to anaesthetic care are introduced as part of this study; it is a statistical analysis of existing clinical registry data.
Interventions
The exposure of interest is the national regulatory withdrawal of pholcodine-containing cough medicines from the Australian market on 8 March 2023. This is a natural experiment at the population level: we compare monthly counts of clinically investigated perioperative allergic reactions attributed to neuromuscular blocking agents (NMBAs), antibiotics, and any agent before and after the pholcodine ban, using a state-wide allergy registry.
No study-specific drugs, procedures, or changes to anaesth
The exposure of interest is the national regulatory withdrawal of pholcodine-containing cough medicines from the Australian market on 8 March 2023. This is a natural experiment at the population level: we compare monthly counts of clinically investigated perioperative allergic reactions attributed to neuromuscular blocking agents (NMBAs), antibiotics, and any agent before and after the pholcodine ban, using a state-wide allergy registry. No study-specific drugs, procedures, or changes to anaesthetic care are introduced by the investigators; all anaesthesia and perioperative management follow usual clinical practice. The “intervention” is entirely external to the health service and consists of the regulatory cancellation and recall of all pholcodine-containing cough products. The information in the database includes the medical history, anaesthetic record, and serum tryptase and Specific IgE results were available, and guideline-concordant skin testing. The source of information is the Western Australian Anaesthetic Drug Reaction Clinic Registry. Participants were not actively involved, consent for inclusion in the registry and use in ethics-committee approved studies was gained prospectively. The duration of observation post-ban will be from 8/3/23 to 01/01/26. The total duration of the study was 01/01/16 to 01/01/26
Sponsors
Sir Charles Gairdner Hospital
Eligibility
Sex/Gender
All
Healthy volunteers
No
Inclusion criteria
• Patients of any age and sex who experienced a suspected perioperative allergic reaction during anaesthesia or the immediate perioperative period, • Reaction referred to and investigated by the Western Australian Anaesthetic Drug Reaction Clinic, the prospectively approved state-wide perioperative allergy registry, • Index reaction occurred between 1 January 2016 and 24 November 2025, and • Registry record includes a documented event date and assignment of a primary allergen by the clinic’s multidisciplinary review process.
Exclusion criteria
• Reactions not occurring in the perioperative period (e.g. non-anaesthetic or non-surgical drug reactions), • Cases without a recorded date of the index reaction, • Cases in which the perioperative reaction was not investigated through the Western Australian Anaesthetic Drug Reaction Clinic (i.e. not in the prospectively approved registry), • Registry entries lacking assignment of a primary allergen after clinical work-up, and • Reactions occurring outside the study period (before 1 January 2016 or after 24 November 2025).
Outcome results
None listed