Infectious diseases (London, England)
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The aim of this study was to investigate which markers in serum and in the synovial fluid have the highest diagnostic potential for predicting septic arthritis and periprosthetic joint infections (PJIs). The likelihood ratio assesses the diagnostic utility of a diagnostic test and the likelihood that a patient has a disease. ⋯ The SFWBC, CRPS, %PMN and synovial lactate were the best inflammatory markers in predicting septic arthritis. Synovial lactate levels > 10 mmol/l or an SFWBC > 50 × 10(3)/μl substantially increased disease probability, while SFWBC < 1.0 × 10(3)/μl or CRPS < 0.5 mg/dl diminished the post-test probability of septic arthritis considerably. An SFWBC < 1.1 × 10(3)/μl or a %PMN < 70% made a PJI unlikely, while SFWBC > 20 × 10(3)/μl or %PMN > 86% increased the post-test probability of a PJI. The use of the corresponding interval likelihood ratios could help physicians to estimate the probability of septic arthritis and PJI more accurately.