Is combining serum interleukin-6 and C-reactive protein a reliable diagnostic tool in periprosthetic joint infections?

BACKGROUND: Because there is no single gold standard method for the diagnosis of periprosthetic joint infection (PJI), the combination of valuable methods to evaluate infection appears to achieve a better diagnostic result. The objective of the present study was to evaluate the diagnostic value of serum interleukin (IL)-6 and C-reactive protein (CRP) for the diagnosis of PJI. METHODS: PubMed, Embase, and the Web of Science databases were searched for articles describing PJI diagnosis using serum IL-6 and CRP published between January 1990 and December 2019. RESULTS: Eight studies were included in the meta-analysis. The pooled sensitivity was 0.84 (95% confidence interval [CI], 0.80−0.88) for the combined method (serum IL-6 and CRP) in series and parallel approaches, 0.87 (95% CI, 0.82−0.90) for IL-6, and 0.84 (95% CI, 0.79−0.88) for CRP. The pooled specificity was 0.85 (95% CI, 0.82−0.88) for the combined method, 0.83 (95% CI, 0.79−0.87) for IL-6, and 0.83 (95% CI, 0.79−0.87) for CRP. The combined method had the highest value for the area under the curve (0.9453), followed by IL-6 (0.9237) and CRP (0.9074). Subgroup analyses showed that the sensitivity of the combined method in parallel tests was higher than that in IL-6 or CRP (94% vs. 89% and 84%, respectively). Serial testing of the combined method showed increased specificity compared to a single indicator (96% vs. 83% and 80%). CONCLUSION: The combination of serum IL-6 and CRP was a reliable tool for the diagnosis of periprosthetic hip and knee infection, demonstrating a better diagnostic accuracy than single marker analysis.