A team of researchers from Mayo Clinic set out to assess the accuracy of the alpha-defensin test for diagnosing periprosthetic joint infection (PJI) in patients with inflammatory diseases.
Biomarker Accurate for Periprosthetic Joint Infections
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#periprostheticjointinfectionSecondary#pji#systemicinflammatorydisease
Their work, “Diagnostic Accuracy of the Alpha-Defensin Test for Periprosthetic Joint Infection in Patients With Inflammatory Diseases,” appears in the April 12, 2019 edition of The Journal of Arthroplasty.
Co-author Wael Barsoum, M.D., CEO and president, Cleveland Clinic Florida commented to OTW, “It is difficult to diagnose periprosthetic joint infection (PJI) in some patients. Alpha-defensin is a biomarker that has been shown to be helpful in this diagnosis, but some studies have suggested that its results may not be accurate in patients with systemic inflammatory disease (SID).”
The researchers conducted a retrospective review of 1,374 cases that underwent revision total hip or knee arthroplasty from 2014-2017. Included were patients with inflammatory diseases who received a 1-stage revision arthroplasty, the first stage of 2-stage revision arthroplasty, or irrigation and debridement with available preoperative alpha-defensin results. The Musculoskeletal Infection Society criteria were used to classify cases as infected or not infected; 41 cases met the inclusion criteria.
The researchers found that the alpha-defensin test showed a sensitivity of 93%, a specificity of 100%, a positive predictive value of 100%, a negative predictive value of 96%, and an accuracy of 97% for diagnosing PJI.
Dr. Barsoum, also the Robert and Suzanne Tomsich Distinguished Chair in Healthcare Innovation, commented to OTW, “Use of this test in this patient population seems to be reliable and can be used in combination with other important criteria (e.g., serum C-reactive protein, serum erythrocyte sedementation rate, serum D-dimer, synovial polymorphonuclear percentage, synovial white blood cells count, leukocyte esterase) when determining whether or not a patient has a PJI.”
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This is a fascinating development. In my practice we've seen similar outcomes with the revised protocol. The key differentiator seems to be patient selection criteria. Has anyone else noticed the correlation with BMI thresholds?
Great point. I'd push back slightly on the conclusion, the sample size in the cited study is too small to draw population-level inferences. That said, the directional signal is compelling and worth a larger RCT.
We implemented a similar approach last year. Early results are promising but we're still gathering 12-month follow-up data. Happy to share our protocol if anyone is interested.
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