Patient-Related Risk Factors for Postoperative Infection Following Shoulder Arthroscopy: An Analysis of Over 420,000 Patients

OBJECTIVES: Shoulder arthroscopy has been traditionally associated with low infection rates. A recent large study reported a 0.27% infection rate following shoulder arthroscopy. The yearly incidence of infectious complications is not negligible, however, given the large volume of procedures performed. Little data exists regarding risk factors for infection following shoulder arthroscopy, as previous studies are not adequately powered to evaluate for infection. The objective present study was to determine patient-related risk factors for infection following shoulder arthroscopy a large insurance database. METHODS: The PearlDiver patient records database was used to query the 100% Medicare Standard Analytic Files from 2005-2012 patients undergoing shoulder arthroscopy procedures using CPT codes 29806, 29807, 29824, 29826, 29827 and 29828. Patients undergoing shoulder arthroscopy for a diagnosis of infection were excluded. Postoperative infection within 90 days postoperatively was then assessed using both ICD-9 codes for a diagnosis of postoperative infection or septic shoulder arthritis, or a procedure for these indications, including either open or arthroscopic irrigation and debridement. 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, including: age, gender, obesity, morbid obesity, tobacco use, alcohol abuse, diabetes mellitus, inflammatory arthritis, hypercoagulable disorder, hyperlipidemia, hypertension, peripheral vascular disease, congestive heart failure, coronary artery disease, chronic lung disease, chronic liver disease, chronic kidney disease, use of hemodialysis, major depression, hypothyroidism and chronic anemia. Adjusted odds ratios (OR) and 95% confidence intervals (CIs) were calculated for each risk factor, with P < 0.05 considered statistically significant. RESULTS: 422,245 patients met all inclusion and exclusion criteria. There were 883 infections within 90 days postoperatively (0.21%). Intraoperative steroid injection was an independent risk factor for postoperative infection (OR 1.3, P = 0.001). There were also numerous independent patient-related risk factors for infection, which are provided in Table 1. The most significant were: chronic anemia (OR 1.7, P < 0.0001), age < 65 years (OR 1.5), P < 0.0001), obesity (OR 1.5, P < 0.0001) and depression (OR 1.5, P < 0.0001) [Table 1]. CONCLUSION: The risk of infection following shoulder arthroscopy in the present series of over 420,000 patients was 0.21%, similar to reported numbers from other large series. Intraoperative steroid injection was a significant, independent risk factor for postoperative infection. There were also numerous significant patient-related risk factors for postoperative infection, including obesity, younger age, chronic anemia, depression and alcohol use among others.