Risk Factors for Infection After Shoulder Arthroscopy in a Large Medicare Population

Background: Shoulder arthroscopy is well established as a highly effective and safe procedure for the treatment for several shoulder disorders and is associated with an exceedingly low risk of infectious complications. Few data exist regarding risk factors for infection after shoulder arthroscopy, as previous studies were not adequately powered to evaluate for infection. Purpose: To determine patient-related risk factors for infection after shoulder arthroscopy by using a large insurance database. Study Design: Case-control study; Level of evidence, 3. Methods: The PearlDiver patient records database was used to query the 100% Medicare Standard Analytic Files from 2005 to 2014 for patients undergoing shoulder arthroscopy. Patients undergoing shoulder arthroscopy for a diagnosis of infection or with a history of prior infection were excluded. Postoperative infection within 90 days postoperatively was then assessed with International Classification of Diseases, Ninth Revision codes for a diagnosis of postoperative infection or septic shoulder arthritis or a procedure for these indications. A multivariate binomial logistic regression analysis was then utilized to evaluate the use of an intraoperative steroid injection, as well as numerous patient-related risk factors for postoperative infection. Adjusted odds ratios (ORs) and 95% CIs were calculated for each risk factor, with P <. 05 considered statistically significant. Results: A total of 530,754 patients met all inclusion and exclusion criteria. There were 1409 infections within 90 days postoperatively (0.26%). Revision shoulder arthroscopy was the most significant risk factor for infection (OR, 3.25; 95% CI, 2.7-4.0; P <. 0001). Intraoperative steroid injection was also an independent risk factor for postoperative infection (OR, 1.46; 95% CI, 1.2-1.9; P =.002). There were also numerous independent patient-related risk factors for infection, the most significant of which were chronic anemia (OR, 1.58; 95% CI, 1.4-1.8; P <. 0001), malnutrition (OR, 1.42; 95% CI, 1.2-1.7; P =.001), male sex (OR, 2.71; 95% CI, 2.4-3.1; P < .0001), morbid obesity (OR, 1.41; 95% CI, 1.2-1.6; P < . 0001), and depression (OR, 1.36; 95% CI, 1.2-1.5; P <. 0001). Conclusion: Intraoperative steroid injection was a significant independent risk factor for postoperative infection after shoulder arthroscopy. There were also numerous significant patient-related risk factors for postoperative infection, including revision surgery, obesity, male sex, chronic anemia, malnutrition, depression, and alcohol use, among others.