A Preoperative Scale for Determining Surgical Readmission Risk After Total Hip Replacement

IMPORTANCE Total hip replacement is a commonly performed orthopedic procedure for the treatment of painful arthritis, osteonecrosis, or fracture. OBJECTIVE To develop and verify a scale for predicting readmission rates for total hip replacement patients and allow for the development and implementation of readmission risk-reduction strategies. DESIGN, SETTING, AND PARTICIPANTS Discharge data on 268 518 patients from New York and California (derivation cohort) and 153 560 patients from Florida and Washington (validation cohort) were collected from the State Inpatient Database, a part of the Healthcare Cost and Utilization Project of the Agency for Healthcare Research and Quality (2006-2011). Analysis of the derivation cohort was performed in July 2013 and analysis of the validation cohort was performed in August 2014. Demographic and clinical characteristics of patients undergoing total hip replacement were abstracted. The Readmission After Total Hip Replacement Risk Scale was developed to predict readmission risk. MAIN OUTCOME AND MEASURE Readmission rate. RESULTS Of the 268 518 patients from New York and California (derivation cohort), 151 009 (56.2%) were women and 216 477 (80.6%) were white. Of the 153 560 patients from Florida and Washington (validation cohort), 86 534 (56.3%) were women and 120 591 (78.5%) were white. Overall 30-day readmission rate was 5.89% for the derivation cohort and 5.82% for the validation cohort. Readmission rates for men and women were 5.79% and 6.08% for the derivation cohort (odds ratio [OR], 1.05; 95% CI, 1.02-1.09) and 5.80% and 5.84% for the validation cohort (OR, 0.99; 95% CI, 0.95-1.04), respectively. The following were all determined to be associated with increased risk of readmission after total hip replacement: being older than 71 years (OR, 1.83; 95% CI, 1.77-1.89), African American (OR, 1.23; 95% CI, 1.15-1.31), and in the lowest income quartile (OR, 1.18; 95% CI, 1.12-1.24); revision replacement (OR, 1.82, 95% CI, 1.75-1.90); liver disease (OR, 1.57; 95% CI, 1.39-1.77); congestive heart failure (OR, 1.49; 95% CI, 1.38-1.61); chronic pulmonary disease (OR, 1.33; 95% CI, 1.27-1.39); renal failure (OR, 1.26; 95% CI, 1.18-1.36); diabetes (OR, 1.21; 95% CI, 1.16-1.27); fluid and electrolyte disorder (OR, 1.21; 95% CI, 1.14-1.27); anemia (OR, 1.19; 95% CI, 1.15-1.25); rheumatoid arthritis (OR, 1.19; 95% CI, 1.10-1.29); coagulopathy (OR, 1.19; 95% CI, 1.08-1.32); hypertension (OR, 1.17; 95% CI, 1.12-1.21); and obesity (OR, 1.15; 95% CI 1.09-1.21). They were used to create the Readmission After Total Hip Replacement Risk Scale, which was applied to the validation cohort and explained 89.1% of readmission variability in that cohort. CONCLUSIONS AND RELEVANCE Data derived from patients in the New York and California State Inpatient Database were reliably able to explain readmission variability for patients in the Florida and Washington State Inpatient Database at a rate of 89.1% based on known preoperative risk factors. Risk-stratification models, such as the Readmission After Total Hip Replacement Risk Scale, can identify high-risk patients for readmission and permit implementation of patient-specific readmission-reduction strategies to reduce readmissions and health care expenditures.