Risk Factors for Unexpected Hospital Admission Following Achilles Tendon Repair: A National Database Study

INTRODUCTION Achilles tendon rupture (ATR) repair is one of the most common orthopaedic surgeries performed in the United States, however there is a paucity of literature on predisposing risk factors for hospital readmissions. The purpose of this study is to identify risk factors for 30-day readmission in patients undergoing ATR repair with emphasis on procedures performed in the outpatient setting. Specifically, we examine: 1) 30-day post-operative hospital readmission rates; 2) the medical comorbidities and patient characteristics that predisposed this cohort to post-operative complications; and 3) the complications leading to readmission. METHODS The ACS-NSQIP was queried for patients who underwent ATR from 2015 to 2019 using CPT code 27650 in all fields yielding a sample size of 3,887 cases. The following demographic, lifestyle, and comorbidity variables were recorded: age, sex, race, BMI, morbid obesity (BMI ≥ 40.00 kg/m2), bleeding disorders, chronic obstructive pulmonary disease (COPD), diabetes mellitus, hypertension, tobacco use, and chronic steroid use. The primary outcome of 30-day readmission was defined as unplanned hospital readmission likely related to the principal procedure. Independent samples Student’s t-tests, chi-squared, and, where appropriate, Fisher’s exact tests were used in univariate analyses to identify demographic, lifestyle, and peri-operative variables related to 30-day readmission following ATR. Multivariate logistic regression modeling was subsequently performed. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated and reported. RESULTS Of the 3,887 patients included in our sample, 28 were readmitted within the 30-day post-operative period, corresponding to a readmission rate of 0.73%. Significant relationships with univariate analyses between readmission status and the following patient variables included: mean patient age (p = 0.02); hypertension (p < 0.001); BMI (p = 0.01); morbid obesity (p = 0.002); ASA Classification (p = 0.006); and bleeding disorders (p = 0.03). Multivariate logistic regression modeling confirmed that the following patient variables were associated with statistically significantly increased odds of readmission: age, p = 0.02), OR = 1.03, 95% CI [1.01, 1.06]; hypertension, p < 0.001, OR = 3.82, 95% CI [1.81, 8.06]; BMI, p = 0.01, OR = 1.06, 95% CI [1.01, 1.11]; morbid obesity, p = 0.004, OR = 3.53, 95% CI [1.49, 8.36]. CONCLUSION Our study indicated that only 0.73% of patients were readmitted after their outpatient procedure. Patients who: 1) have BMIs greater than 40; 2) are older in age 3) have hypertension; and 4) a higher ASA Classification were at increased risk for readmission.