Impact of antibiotics allergy labels on clinical outcomes in ICU patients: A 15‐year retrospective cohort study

AIM: The impact of antibiotics allergy labels (AALs) on intensive care unit (ICU) patients remains unclear. This study aimed to evaluate the effect of AALs on clinical outcomes in ICU patients. METHODS: A retrospective cohort study was conducted on ICU patients in Huashan Hospital, Shanghai, China, between January 2005 and December 2019. AALs were identified from electronic health records. Clinical characteristics and outcomes were compared between patients with and without AALs before and after propensity score matching (PSM). Multivariable logistic regression analysis was conducted to identify risk factors for carbapenem-resistant Enterobacterales (CRE) acquisition. RESULTS: Among 1514 patients, 183 (12%) had AALs, with penicillin being the most frequently reported (78%). After PSM, patients with AALs received fosfomycin more frequently (23% vs. 10%, p = .001) and had lower use of third-/fourth-generation cephalosporins and β-lactam/β-lactamase inhibitor combinations (BLBLIs) (46% vs. 70%, p = .000). Median antibiotic duration was slightly shorter in the AAL group (10 vs. 11 days, p = .023). Mortality and 30-day readmission rates did not differ significantly. However, extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E) acquisition was lower in the AAL group (3% vs. 8%, p = .043). Patients with AALs had a shorter hospital stays (12 vs. 14 days, p = .002) and reduced hospitalization costs (44 954 vs. 59 279 Yuan, p = .001). CONCLUSION: AALs significantly altered antibiotic prescribing but were not associated with worse outcomes. Unexpectedly, AALs correlated with lower ESBL-E acquisition, shorter hospitalization and reduced costs, suggesting complex effects that warrant further prospective investigation.