Selected Secondary Analyses from the PARITY Trial: Introduction.

Anatomic reconstruction of the femur or tibia for oncologic indications is most commonly achieved with a modular metallic and polyethylene endoprosthesis. Endoprosthetic reconstructions are complex procedures, and therefore orthopaedic oncologic patients are at high risk for postoperative complications. The most common surgical complication is a surgical site infection (SSI). While SSIs are often managed with multiple revision procedures, the risk of ultimate amputation is high. Various strategies are employed to mitigate the risk of SSI, including perioperative intravenous prophylactic antibiotics. The overuse of antibiotics is of major public health importance and is associated with antibiotic-related complications and antibiotic resistance. Antibiotic overuse can result in antibiotic-associated diarrhea, frequently caused by Clostridioides difficile. Although antibiotic-associated diarrhea is generally mild and self-limiting, gut infection with C. difficile can be severe and may lead to toxic megacolon, organ failure, or even death. The most effective prophylactic antibiotic regimen remains uncertain; therefore, the duration of postoperative antibiotics varies across surgeons and hospitals, and the use of prolonged antibiotics is widespread. We conducted an international multicenter randomized controlled trial to determine if 5 days compared with 1 day of postoperative prophylactic antibiotics decreases the rate of SSIs in patients undergoing endoprosthetic reconstruction of the lower extremity for oncologic indications. The Prophylactic Antibiotic Regimens In Tumor surgerY (PARITY) trial enrolled 604 patients across 48 centers in 12 countries. To our knowledge, this trial was the first-ever collaborative prospective trial initiated and led by orthopaedic oncologists. Please refer to the Trial Overview below for further details on the results of the PARITY trial. Answering clinical questions about rare conditions requires an enormous international, collaborative effort. To date, the PARITY trial has generated the largest prospective data set in orthopaedic oncology. This robust data set provides a unique opportunity to explore and answer other relevant clinical questions in this patient population. The following supplement addresses 13 of these highly relevant clinical questions using data from the PARITY trial. PARITY Trial Overview The PARITY trial was a blinded randomized clinical superiority trial that was conducted at 48 clinical sites in 12 countries from January 1, 2013, to October 29, 20191. The trial included patients with a primary bone tumor, a soft-tissue sarcoma that had invaded the femur or tibia, or oligometastatic bone disease of the femur or tibia who required surgical management with excision and endoprosthetic reconstruction. A total of 611 patients were enrolled, and 7 were excluded for ineligibility. A 1- or 5-day blinded regimen of postoperative prophylactic intravenous cephalosporin (cefazolin or cefuroxime) was administered within 8 hours after skin closure and was re-administered every 8 hours thereafter. Patients randomized to the 1-day regimen received identical saline solution doses every 8 hours for the remaining 4 days. The primary outcome was an SSI (i.e., superficial incisional, deep incisional, or organ space infection) classified according to the criteria established by the Centers for Disease Control and Prevention within 1 year after surgery. Secondary outcomes included antibiotic-related complications, unplanned additional operations, oncologic and functional outcomes, and mortality. Of the 604 patients who were included in the final analysis (mean age [and standard deviation], 41.2 ± 21.9 years; 361 [59.8%] male), 293 were randomized to a 5-day regimen and 311 were randomized to a 1-day regimen. An SSI occurred in 44 patients (15.0%) who had been randomized to the 5-day regimen and in 52 patients (16.7%) who had been randomized to the 1-day regimen (hazard ratio, 0.93; 95% confidence interval [CI], 0.62 to 1.40; p = 0.73). Antibiotic-related complications occurred in 15 patients (5.1%) who had been randomized to the 5-day regimen and in 5 patients (1.6%) who had been randomized to the 1-day regimen (hazard ratio, 3.24; 95% CI, 1.17 to 8.98; p = 0.02). Other secondary outcomes did not differ significantly between treatment groups. Although the PARITY trial did not confirm the superiority of a 5-day regimen of postoperative intravenous antibiotics over a 1-day regimen in preventing SSI, the 5-day regimen resulted in significantly more antibiotic-related complications.