Prolonged Post-surgical Drain Retention Increases Risk for Deep Wound Infection After Spine Surgery

Objective: Surgical site infections (SSIs) complicate 1% to 9% of elective spine surgeries. Previously identified risk factors include diabetes mellitus type 2, obesity, and chronic kidney disease. We sought to determine whether the use of postoperative surgical site drains is associated with deep SSIs. Methods: We retrospectively identified patients operated for deep SSIs after surgery for degenerative spine pathologies between July 2016 and December 2018. Patients were excluded if the reason for operation was other than deep SSI or if their primary operation was for infection or tumor. Using their index procedure and the electronic medical record, patients were matched to controls based on age, surgical invasiveness, International Classification of Diseases, Tenth Revision, Clinical Modification code, race, and sex. Our main outcome of interest was whether drain retention time, total output, or daily output differed significantly between cases and controls. Results: We identified 38 patients who met inclusion criteria. Infected patients had a higher body mass index (34.2 vs. 29.9 kg/m²; P = 0.001), higher odds of having diabetes mellitus type 2 (55.3% vs. 18.4%; P = 0.002), longer drain retention time (5.5 vs. 3.5 days; P = 0.02), and longer inpatient stay (9.5 vs. 4.3 days; P = 0.005). Multivariable logistic regression demonstrated that even after controlling for the other risk factors, drain retention time independently predicted postoperative surgical site infection (odds ratio: 1.36; P = 0.02). Conclusions: Prolonged surgical drain retention correlates with risk of deep SSI after surgery for degenerative spine disease independent of surgical invasiveness, diabetes mellitus type 2 status, and total drain output. Our data suggest early postoperative drain removal may potentially decrease the risk of SSI and shorten duration of hospital stay.