The Journal of Arthroplasty, Volume 35, Issue 1, 12 - 16.e1

Oncology Patients Are High Cost Outliers in Total Joint Replacement Bundled Payment Systems

Woelber, Erik et al.
Hip Knee


In 2016, the Centers for Medicare and Medicaid Services began its first mandatory bundled payment program, the Comprehensive Care for Joint Replacement (CJR) model, which covers a 90-day episode of care. This study determined whether oncology patients enrolled in the CJR bundle incur higher hospital costs than patients with osteoarthritis (OA).


A retrospective review of all patients enrolled in the CJR bundled payments system from April 1, 2016 to June 31, 2018 at a single academic medical center was conducted. To determine whether tumor patients had higher total episode costs, this group was compared to patients diagnosed with OA using a 2-tailed t-test. To adjust for moderators of total hospital costs, we used generalized linear regression with a log-link, including multiple variables abstracted from chart review.


Three hundred fourteen patients met inclusion criteria (12 primary or metastatic tumors, 302 OA). Fifty-eight percent of tumor patients were over the target price vs 16% of OA patients. The mean tumor patient had $40,862 for total internal hospital costs compared to $16,356 in the OA group (P < .001). Length of stay was greater in the tumor group (6.75 vs 2.0 days, P < .001). A greater percentage of tumor patients were discharged to a skilled nursing facility (67% vs 27%, P = .006) with significantly higher skilled nursing facility episode costs ($18,852 vs $7731, P = .04). With adjustment for fracture status, tumor patients were 5.36 times more likely to exceed the CJR target price than OA patients (risk ratio 5.36, confidence interval 3.44-8.35, P < .001) and 50 times more likely to be outliers over the regional threshold than OA patients (risk ratio 50.33, confidence interval 16.33-155.19, P < .001).


Oncology patients enrolled in the CJR bundled payment model incur significantly higher costs and have higher cost variability than patients with OA. We recommend that oncology patients be excluded from the CJR bundle.

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