The positive likelihood ratio (PLR) and negative likelihood ratio (NLR) of serum IL-6 for PJI diagnosis were 6.4 (95% CI: 2.9–14.1) and 0.31 (95% CI: 0.22–0.44), respectively, while those of synovial fluid IL-6 were 9.5 (95% CI: 5.3–17.2) and 0.09 (95% CI: 0.04–0.21), respectively (Fig. 3). The gene discussed is IL6; the disease is juvenile polyposis syndrome.