Supplementary Material for: Prevalence of trimethoprim-sulfamethoxazole adverse reaction mislabelling in Australia

Introduction: Trimethoprim-sulfamethoxazole (TMP-SMX) is an important antibiotic, with the most compelling indications for Pneumocystis jirovecii pneumonia prophylaxis and methicillin-resistant Staphylococcus aureus treatment. Previous adverse reactions (AR) to TMP-SMX may limit the usability of TMP-SMX. Electronic medical record (EMR) recording of AR for other antibiotics has previously been shown to be inaccurate; however, the extent to which this occurs for TMP-SMX is unknown. Methods: A multi-centre retrospective observational study was conducted for consecutive inpatient admissions over a 2.5-year period commencing 2020. Adverse reactions to TMP-SMX recorded in the EMR were collected and reviewed by two independent medical officers using a pre-defined expert criteria for the classification of allergies and intolerances. Results: TMP-SMX AR were present in the EMR of 759 individuals (prevalence 0.6%). The majority were labelled as allergy (725, 95.5%) rather than intolerance (34, 4.5%). Most common AR were rash, vomiting, and swelling. When classified against the gold-standard expert criteria, there were 437 allergies (57.6%) and 159 intolerances (21.0%). Overall, the number of incorrect EMR AR labels was 133/759 (17.5%). Both medical and surgical specialties had significant numbers of patients with TMP-SMX AR labels and incorrectly classified EMR AR labels. Conclusion: TMP-SMX AR labels affect inpatients admitted under multiple specialty units. The user-entered categorisation as allergy or intolerance labels in EMRs are frequently used incorrectly. These incorrect labels may inappropriately contraindicate the use of TMP-SMX, and formal evaluation of TMP-SMX ARs with immunologic assessment and relabelling where appropriate may increase use of this agent.

引言：甲氧苄啶-磺胺甲噁唑（Trimethoprim-sulfamethoxazole, TMP-SMX）是一类重要的抗菌药物，其核心临床适应证包括肺孢子菌肺炎的预防以及耐甲氧西林金黄色葡萄球菌感染的治疗。既往患者对TMP-SMX发生的不良反应（Adverse Reaction, AR）可能会限制该药物的临床应用。既往研究已证实，电子病历（Electronic Medical Record, EMR）中记录的其他抗菌药物不良反应存在不准确的情况，但针对TMP-SMX不良反应的此类记录不准确程度目前仍不明确。

方法：本研究为多中心回顾性观察性研究，纳入2020年起2.5年周期内的连续住院患者。研究人员收集了电子病历中记录的TMP-SMX不良反应病例，并由两名独立医务人员按照预先设定的过敏与不耐受分类专家标准进行审核。

结果：电子病历中共记录759例患者存在TMP-SMX不良反应（患病率0.6%）。其中绝大多数被标注为过敏反应（725例，占95.5%），仅少数被归类为不耐受反应（34例，占4.5%）。最常见的不良反应类型为皮疹、呕吐及肿胀。按照金标准专家分类标准重新审核后，最终确诊过敏反应437例（占57.6%），不耐受反应159例（占21.0%）。总体而言，电子病历中不良反应记录分类错误的比例为133/759（17.5%）。内科与外科专科均存在大量带有TMP-SMX不良反应记录且分类错误的患者。

结论：TMP-SMX不良反应记录标签可影响多专科收治的住院患者。电子病历中由用户录入的过敏/不耐受分类标签常存在使用不当的情况。此类错误标签可能会不恰当地禁用TMP-SMX，通过免疫功能评估对TMP-SMX不良反应进行正式评估，并在适当时机重新分类标签，或可提升该药物的临床使用率。