June 27, 2019
1 min read

Traditional laboratory markers may hold low diagnostic utility for PJI in immunosuppressed patients

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Alexander L. Lazarides

White blood cell counts and inflammatory markers may hold lower diagnostic utility among patients in an immunosuppressed state who experienced periprosthetic joint infection after total joint arthroplasty, according to published research.

In a retrospective review of 90 patients with an immunosuppressed state who experienced periprosthetic joint infection (PJI) after primary or revision TJA, Alexander L. Lazarides, MD, and colleagues performed a multivariable analysis to identify independent factors associated with acute and chronic infection defined by Musculoskeletal Infection Society criteria. Researchers used area under the receiver-operator curve to determine the best supported laboratory cut points for identifying infection.

Results showed 36.7% of patients had rheumatoid arthritis, 13.3% had systemic lupus erythematosus, 8.9% had irritable bowel syndrome, 3.3% had psoriatic arthritis and 37.8% had other autoimmune or rheumatologic disorders. Overall, the patients identified had a total of 172 aspirations with a mean follow-up from aspiration of 33 months.

Researchers found an independent correlation between synovial fluid cell count and synovial percent neutrophils with both acute and chronic infection, according to results of the multivariate analysis. Results showed a synovial fluid cell count cutoff value of 5,679 nucleated cells/mm3 and of 1,293 nucleated cells/mm3 maximized the area under the receiver-operator curve for predicting acute and chronic infection, respectively.

“We found that traditional laboratory values, such as [white blood cell] WBC, [C-reactive protein] CRP and [erythrocyte sedimentation rate] ESR, may hold low diagnostic utility in the diagnosis of prosthetic joint infections in this patient population,” Lazarides told Healio.com/Orthopedics. “Synovial fluid analyses may hold better diagnostic utility, but these values may not be the same as in patients without immunosuppressed or immunomodulated states. When evaluating periprosthetic joint infection, it is important to consider the full scope of patient medical comorbidities and medications as these may impact the diagnosis of prosthetic joint infections.” – by Casey Tingle


Disclosures: Lazarides reports no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures.