Hospital readmissions are undesirable and expensive.1 The Centers for Medicare & Medicaid Services (CMS) use hospital readmission rates as one measure of healthcare quality and hospital performance.2 In addition, the Patient Protection and Affordable Care Act of 2010 established a provision that decreases payments to hospitals with above-average readmission rates.3 Total knee arthroplasties (TKAs) and total hip arthroplasties (THAs) are among the most common surgical procedures leading to readmission and cost almost $20 billion dollars annually in the Medicare population alone.1 Identifying factors that lead to readmissions after certain popular procedures may be a way to improve healthcare quality and outcomes while decreasing costs.
One such operation is shoulder arthroplasty (SA), which has surged in popularity over the past decade and is projected to increase faster than TKAs and THAs.4-6 SA is used to treat a variety of shoulder conditions, including osteoarthritis, inflammatory arthritis, severe proximal humeral fracture, avascular necrosis, and rotator cuff tear arthropathy.7-12 Much as with knee and hip arthroplasty, good outcomes have been reported with SA: decreased pain, improved range of motion, and high patient satisfaction.10,13 However, there have been few studies of rates of readmission after SA and the associated risk factors.3,14,15 The reported rates of early readmission after SA have ranged from 5.6% to 7.3%.3,14,15 These rates are comparable to rates of readmission after TKA (4.0%-6.6%) and THA (3.5%-8.4%).15-17Recently, CMS introduced legislation to void payments for hospital-acquired conditions (HACs), preventable medical conditions that patients develop during or as a result of their hospital care and that were not present on admission.18 Although many factors contribute to readmission, a recent study regarding all-cause readmission during the first 30 days after discharge found that almost 50% of 30-day readmissions after knee and hip replacements were potentially preventable.19 HACs resulting in readmission after SAs make up 9.3% to 34.5% of all readmissions, after anatomical total shoulder arthroplasties (ATSAs) and reverse total shoulder arthroplasties (RTSAs).3,14 The most common HACs include retained foreign body after surgery, air embolism, falls and trauma, catheter-associated urinary tract infection (CAUTI), surgical-site infection, deep vein thrombosis (DVT), and pulmonary embolism (PE).18 Raines and colleagues16 found that HACs accounted for 41.7% of all complications in knee or hip arthroplasty and that HACs were the greatest predictors of early readmission after both procedures.
We conducted a study to evaluate rates of readmission within 30 days after ATSA and RTSA and to describe the independent risk factors for readmission. We hypothesized that the rate of readmission after SA would be similar to the rate after knee and hip arthroplasty and that readmission risk factors would be similar. Elucidating these rates and associated risk factors may ultimately help to minimize the burden of disability on patients and the burden of financial costs on healthcare institutions.
Materials and Methods
Institutional Review Board approval was not required for this study, and all data used were de-identified to Health Insurance Portability and Accountability Act (HIPAA) standards. We used the American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) database for this study. The NSQIP was developed in the 1990s to improve surgical quality in the Veterans Health Administration and was later adapted by the ACS.20 NSQIP follows patients for 30 days after operations and provides clinical data and outcome measures that are closely regulated and internally audited.21 The program has continued to expand and now includes more than 400 institutions. The NSQIP database has been validated as a reliable source of surgical outcomes data, including outcomes data for orthopedic procedures, and has been used in other studies of readmissions.17,22
In the present study, the ACS-NSQIP files for the period 2011-2013 were queried for all total shoulder arthroplasties (TSAs) (Current Procedural Terminology [CPT] code 23472, which includes ATSA and RTSA). Descriptive analysis was performed to determine the overall readmission rate as well as the percentages of readmissions for medical and surgical complications. Reasons for readmission were collected from 2012 and 2013 (information from 2011 was absent).
The various patient parameters compiled within the database were examined in a review of ATSAs and RTSAs. Demographics, comorbidities, operative characteristics, and predischarge complications were amassed from these data. Demographics included age, sex, race, body mass index, smoking status, preoperative functional health status, and American Society of Anesthesiologists (ASA) score. Comorbidities included diabetes mellitus, hypertension, chronic corticosteroid use, coagulation disorder, peripheral vascular disease, chronic obstructive pulmonary disease (COPD), cardiac comorbidity (including congestive heart failure, history of myocardial infarction, previous coronary intervention or cardiac surgery, and angina), renal comorbidity (including acute renal failure and preoperative dialysis), neurologic comorbidity (including impaired sensorium, hemiplegia, history of transient ischemic attack, and history of cerebrovascular accident with or without residual deficit), and preoperative blood transfusion. Operative characteristics included resident involvement, operative time more than 1 SD from the mean (>164.4 minutes), intraoperative blood transfusion, and revision surgery. Predischarge complications included pneumonia, CAUTI, DVT, PE, postoperative bleeding that required transfusion, cerebrovascular accident, myocardial infarction, and sepsis. Surgical-site infection, CAUTI, DVT, and PE were selected for analysis because these HACs are common in our cohort.
After the data on these characteristics were collected, univariate analysis was performed to determine association with any readmission. Factors with P < .20 were then entered into multivariate analysis to determine independent risk factors for readmission. This P value was selected to make the model inclusive of any potentially important predictor. Univariate analysis was performed using the Fisher exact test. Multivariate analysis was performed using backward conditional binary logistic regression. Statistical significance was set at P < .05. All analysis was performed with SPSS Version 22.0 (SPSS).