We sought to investigate how patient demographics and baseline comorbidities varied between hip fracture and total joint arthroplasty patients across New York State and to determine implications of differences within the contexts of the bundled payment system.
All Medicare hip and knee arthroplasty and hip fracture cases in the New York State SPARCS database between 2004 and 2014 were identified. Hospitals were categorized geographically into Metropolitan Statistical Areas (MSAs) to determine case distribution. Baseline comorbidities and patient characteristics were stratified.
A total of 218,300 cases were identified; 187,720 arthroplasties and 30,580 hip fractures. The distribution of total cases was significantly skewed toward large MSAs and there was wide variability in the arthroplasty/fracture ratio. Despite similar baseline patient age and gender distributions, there were significant inconsistencies observed in comorbidity burden and length of stay between MSAs. While every MSA had higher average comorbidity scores and longer average lengths of stay in the hip fracture cases than the arthroplasty cases, there was also additional variability observed in the hip fracture cases between each MSA.
The unpredictability observed in hip fracture cases compared to elective arthroplasty can make cost containment in a bundled payment system difficult, particularly for hospitals serving sicker patient populations.