Urine Dipstick Leukocyte Esterase in the Rapid Diagnosis of Septic Arthritis

This study aimed to evaluate the sensitivity and specificity of the leukocyte esterase (LE) band in two groups of patients receiving and not receiving antibiotics and compare the results. This prospective cross-sectional study was conducted on 105 joints with clinical suspicion of infectious arthritis (based on Kocher criteria) admitted in Shohada Hospital, Tabriz, Iran, within 2017-2018. Patients were divided into two groups, including receiving antibiotics (n=29; group 1) and not receiving antibiotics (n=76; group 2). Articular fluid aspiration was performed under sterile conditions with an 18-gauge angiocath with at least 1 ml volume of the hip, knee, ankle, elbow, and shoulder joints. Polymorphonuclear cell percentage count, cell count, Gram staining (GS), culture, and leukocyte esterase test were performed immediately after the aspiration of the specimens. Levels of synovial fluid white blood cell count, serum white blood cell count, PMN, serum glucose, erythrocyte sedimentation rate, C-reactive protein, and time of aspiration (TOA) were significantly higher in the group receiving antibiotics (P<0.05). Synovial glucose levels were significantly lower in the group receiving antibiotics. Furthermore, the positive frequency of glucose esterase, blood culture, GS, serum culture, and ultimate diagnosis of septic arthritis tests were significantly lower in the antibiotic receiving group (P<0.05). The sensitivity, specificity, and positive predictive value of the leukocyte esterase test were obtained at 100%, 0%, and 96.55% in the antibiotic receiving group, respectively. Moreover, in the group not receiving antibiotics, the sensitivity, specificity, positive predictive value, and negative predictive value of the leukocyte esterase test were estimated at 72.22%, 92.50%, 89.66%, 78.72%, respectively. Antibiotic use and the prolongation of TOA lead to increased inflammatory products, which is interfering with lab variables. As a result, they increase the sensitivity of the test. The sensitivity and specificity of the leukocyte esterase test in patients who did not receive antibiotics showed that this was a suitable and reliable laboratory method for the rapid detection of infectious arthritis that required an emergency rescue procedure. Level of evidence: II