How accurately might calprotectin help detect infection around a joint replacement?

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Periprosthetic joint infection (PJI) is an unpredictable and challenging complication of joint replacement. Calprotectin (CLP), a simple, emerging biomarker, has been considered useful for ruling out PJI. This study investigated its diagnostic accuracy and sensitivity.

The researchers searched and screened publications in PubMed, Web of Science, EMBASE and the Cochrane Library from each database’s establishment through June 2021. Using Stata version 16.0, they pooled sensitivity, specificity, positive and negative likelihood ratios (PLR and NLR), diagnostic odds ratio (DOR), the operating characteristic curve and area under the curve (AUC). They assessed variation across studies using I² statistics and investigated its sources through subgroup analyses based on study design, detection method, sample size and cutoff values.

Seven studies comprising 525 patients were included. Pooled sensitivity was 0.94 (95% confidence interval [CI] 0.87–0.98), specificity was 0.93 (95% CI 0.87–0.96), PLR was 13.65 (95% CI 6.89–27.08), and NLR was 0.06 (95% CI 0.02–0.15). The DOR was 222.33 (95% CI 52.52–941.11), and the AUC was 0.98 (95% CI 0.96–0.99).

The authors concluded that synovial CLP is a reliable biomarker that could be used as a diagnostic criterion for PJI in the future. However, uncertainty from the small number of studies and their sample sizes limited their ability to draw definite conclusions.