From left: Dr Steve Man-Hong Cheung, Dr Philip Hei Li, Ms Yip (a patient affected by allergy mislabelling) and Dr Henry Chun-Him FuPatients labelled as allergic to penicillin or other beta-lactam antibiotics face a significantly higher risk of periprosthetic joint infection (PJI) up to 5 years following knee arthroplasty, and should be prioritized for preoperative allergy assessment, researchers from the University of Hong Kong (HKU) have found.
The longitudinal study analyzed data of 4,730 patients (165 with beta-lactam allergies at baseline) who underwent total knee arthroplasty (TKA) between January 1993 and December 2001 at Queen Mary Hospital. Patients labelled as having a beta-lactam allergy were found to have a higher incidence of PJI within the first 5 years post-TKA compared with those without (3.0 vs 0.7 percent; p=0.001). The presence of beta-lactam allergy label was identified as an independent risk factor for PJI (hazard ratio, 4.86; 95 percent confidence interval [CI], 2.05–11.53; p<0.001). Concurring with published literature, male sex and rheumatoid arthritis were associated risk factors for PJI. Following negative drug provocation testing, 95 percent of patients with beta-lactam allergy labels who underwent evaluation (21/22) were successfully delabelled. [Bone Joint J 2025;107:522-528]
PJIs are one of the most concerning and common causes of revision for failed knee arthroplasties. The results underscore the importance of accurate allergy documentation, as mislabelling may lead to unnecessary avoidance of beta-lactam antibiotics and thus obligatory use of alternative second-line antibiotics (such as clindamycin and vancomycin) for preoperative prophylaxis. “Patients labelled with beta-lactam allergy have significantly more overall antibiotic usage, likely due to the higher risk of PJI, warranting a switch to additional alternative antibiotics to broaden coverage or overcome antimicrobial resistance,” wrote the authors.
“Many of these incorrect allergy labels documented in patients’ medical records decades ago could have been based on reactions to the antibiotics during childhood, or on inappropriate skin tests done outside Hong Kong,” said Dr Philip Hei Li of the Department of Medicine, HKU, leader of the research team. “These outdated records prevent patients from receiving optimal care, particularly when it comes to critical surgeries like knee replacements.”
“This study provides the first large-scale evidence from Hong Kong showing the serious consequences of mislabelled penicillin allergies,” said Dr Steve Man-Hong Cheung of the Department of Orthopaedics and Traumatology, HKU, co-leader of the research team. “PJIs are not only life-threatening and cause pain, they also necessitate additional surgery and long-term antibiotic treatment, adding to the burden on our healthcare system.”
To address the urgent need for better drug allergy assessments, a new research-focused pharmacist-led penicillin allergy assessment pilot service has been launched by the LKS Faculty of Medicine of HKU. This service allows patients to directly access expert evaluations at the research-based HKU Community Pharmacy without requiring a prior referral from a doctor. Specially trained pharmacists will conduct initial assessments and seamlessly refer patients to an allergist if further evaluation is required — all within a coordinated and integrated care pathway.