Levent A, Neufeld ME, Piakong P, Lausmann C, Gehrke T, Citak M.
J Arthroplasty. 2021 Jun 30:S0883-5403(21)00590-8
Summary by Alayna Vaughan, BA
Periprosthetic joint infections (PJI) after total knee arthroplasty (TKA) or total hip arthroplasty (THA) occur at a reported rate of 0.5-2%2. A diagnosis of PJI currently relies on the criteria developed by the 2018 International Consensus Meeting (ICM), which used the Musculoskeletal Infection Society (MSIS) and 2013 ICM definitions of PJI as a basis. The new 2018 ICM criteria improved upon the sensitivity of the MSIS criteria for PJI diagnosis while preserving specificity1. To date, there have been few external validation studies investigating the performance of the 2018 ICM minor criteria for diagnosing PJI3. The importance of the ICM minor criteria to differentiate aseptic versus septic PJI lies in the fact that culture negative PJI can be insidious as well as difficult to diagnose. The purpose of the study by Levent et al. was to identify the most accurate preoperative marker for the diagnosis of PJI from five of the 2018 ICM minor criteria: serum C-reactive protein (CRP), synovial white blood cell (WBC) count, synovial polymorphonuclear neutrophil percentage (PNM%), synovial alpha defensin, and synovial leukocyte esterase levels.
This was a retrospective study of 260 patients undergoing revision TKA or THA for any reason at the same hospital by the same orthopedic surgeon between 2015-2017. Serum CRP and synovial PMN%, WBC, alpha defensin, and leukocyte esterase levels were collected from PJI positive (n=109) and negative (n=151) groups. Separate receiver operative characteristic curve analyses for predicting PJI were performed and summarized by the area under the curve (AUC), sensitivity, specificity, accuracy (% correct), positive predictive value, and negative predictive value.
All five preoperative minor criteria were significantly elevated in PJI positive patients. Diagnostic performance for each of the 5 minor criteria had the following AUC: PMN%–0.926, alpha defensin–0.922, WBC–0.916, leukocyte esterase– 0.861, serum CRP 0-860. Combining the 5 preoperative minor criteria resulted in an AUC of 0.9526 for predicting PJI. Using the 2018 ICM thresholds, the accuracy of each criterion was 91.9% (alpha defensin), 87.7% (WBC), 86.5% (PMN%), 85.8% (leukocyte esterase), and 78.1% (CRP); in combination, the 5 criteria achieved an accuracy of 93.5%. Optimizing the threshold for CRP, PMN%, and WBC count increased the accuracy to 79.2%, 90.8%, and 88.1%, respectively; combining the 5 criteria achieved the highest accuracy (94.2%).
The authors concluded that alpha defensin, synovial PMN%, and WBC count were outstanding in terms of diagnostic utility. Leukocyte esterase and serum CRP were considered excellent in terms of diagnostic utility. The authors suggest increasing the weigh-adjusted score of PMN% in the ICM scoring system. Limitations include the lack of serum D-dimer and serum erythrocyte sedimentation rate (ESR) levels which have previously been reported to be useful infection indicators and are included in the 2018 ICM criteria. Additionally, this was a single hospital and single surgeon retrospective study, which may introduce selection bias.
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