Patient-Related Risk Factors for Infection Following Open Carpal Tunnel Release: An Analysis of Over 450,000 Medicare Patients.

PURPOSE: To establish the rate of postoperative infection after open carpal tunnel release (CTR) on a national level using an administrative database and define relevant patient-related risk factors associated with its occurrence.

METHODS: The PearlDiver patient records database was used to query the 100% Medicare Standard Analytic Files retrospectively from 2005 to 2012 for patients undergoing open CTR using Current Procedural Terminology code 64721. Postoperative infection within 90 days of surgery was assessed using both International Classification of Diseases, Ninth Revision codes for diagnoses of postoperative infection or pyogenic arthritis of the wrist and Current Procedural Terminology codes for procedures for these indications, including either open or arthroscopic irrigation and debridement. We used a multivariable binomial logistic regression model that allows for assessment of the independent effect of a variable while controlling for remaining variables to evaluate which patient demographics and medical comorbidities were associated with an increased risk for postoperative infection. Adjusted odds ratios and 95% confidence intervals were calculated for each risk factor, with P < .05 considered statistically significant.

RESULTS: A total of 454,987 patients met all inclusion and exclusion criteria. Of these patients, 1,466 developed a postoperative infection, corresponding to an infection rate of 0.32%. Independent positive risk factors for infection included younger age, male sex, obesity (body mass index of 30 to 40), morbid obesity (body mass index greater than 40), tobacco use, alcohol use, and numerous medical comorbidities including diabetes, inflammatory arthritis, peripheral vascular disease, chronic liver disease, chronic kidney disease, chronic lung disease, and depression.

CONCLUSIONS: The current study reinforced conventional wisdom regarding the the overall low infection rate after CTR and revealed numerous patient-related risk factors that are independently associated with an increased risk of infection after open CTR in patients enrolled in Medicare.

TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic II.