Central Adjudication Committee and Clinical Site Investigator Agreement on Outcomes in the PARITY Trial

BACKGROUND: The detection of a surgical site infection (SSI) in patients with metal implants requires a high degree of clinical acumen. The inherent subjectivity of SSI diagnosis poses a challenge in the design of surgical trials because this subjectivity raises concern for outcome assessment bias. Central Adjudication Committees (CACs) are often utilized to minimize the variability in outcome assessment. Little research has been done to determine the reliability of outcome assessment in trials utilizing a CAC. In the present study, we determined the agreement between the study CAC and the clinical site investigators for the primary and secondary outcome assessments. METHODS: The Prophylactic Antibiotic Regimens in Tumor Surgery (PARITY) trial was a multicenter, blinded, parallel 2-arm, randomized controlled trial that aimed to determine the effect of a 5-day versus 1-day postoperative prophylactic antibiotic regimen on the rate of SSI in patients undergoing surgical excision of tumors in the femur or tibia. The blinded PARITY CAC adjudicated all primary and secondary outcomes identified during the 1-year study follow-up. In the present secondary analysis, the Cohen kappa statistic was utilized to determine the level of agreement. RESULTS: The primary outcome of SSI diagnosis demonstrated a substantial level of agreement between the CAC and the site investigators (0.699; 95% confidence interval [CI], 0.595 to 0.803]). Categorization of the SSI (i.e., superficial, deep, or organ space) showed moderate agreement (0.470; 95% CI, 0.382 to 0.558). Secondary outcomes such as the types of reoperations and the indication for reoperation typically showed substantial to almost perfect agreement, whereas antibiotic-related complications showed fair agreement (0.241; 95% CI, 0.000 to 0.474). CONCLUSIONS: Although there was a substantial level of agreement between the PARITY CAC and site investigators on the diagnosis of an SSI, as well as typically at least substantial agreement on the causes and types of reoperations, there was less agreement regarding the type of SSI and the occurrence of an antibiotic-related complication. Therefore, the CAC appears to have provided value when adjudicating the depth of infection and when determining the causality of medical complications associated with antibiotics. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.