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Risk Adjustment Is Necessary in Value-based Outcomes Models for Infected TKA

Courtney, P. Maxwell, MD; Boniello, Anthony J., MD; Della Valle, Craig J., MD; Lee, Gwo-Chin, MD

Clinical Orthopaedics and Related Research®: October 2018 - Volume 476 - Issue 10 - p 1940–1948
doi: 10.1007/s11999.0000000000000134

Background The Medicare Access and CHIP Reauthorization Act of 2015 provides the framework to link reimbursement for providers based on outcome metrics. Concerns exist that the lack of risk adjustment for patients undergoing revision TKA for an infection may cause problems with access to care.

Questions/purposes (1) After controlling for confounding variables, do patients undergoing revision TKA for infection have higher 30-day readmission, reoperation, and mortality rates than those undergoing revision TKA for aseptic causes? (2) Compared with patients undergoing revision TKA who are believed not to have infections, are patients undergoing revision for infected TKAs at increased risk for complications?

Methods We queried the American College of Surgeons National Surgical Quality Improvement Program database for patients undergoing revision TKA from 2012 to 2015 identified by Current Procedural Terminology (CPT) codes 27486, 27487, and 27488. Of the 10,848 patients identified, four were excluded with a diagnosis of malignancy (International Classification of Diseases, 9th Revision code 170.7, 170.9, 171.8, or 198.5). This validated, national database records short-term outcome data for inpatient procedures and does not rely on administrative coding data. Demographic variables, comorbidities, and outcomes were compared between patients believed to have infected TKAs and those undergoing revision for aseptic causes. A multivariate logistic regression analysis was performed to identify independent factors associated with complications, readmissions, reoperations, and mortality.

Results After controlling for demographic factors and medical comorbidities, TKA revision for infection was independently associated with complications (odds ratio [OR], 3.736; 95% confidence interval [CI], 3.198-4.365; p < 0.001), 30-day readmission (OR, 1.455; 95% CI, 1.207-1.755; p < 0.001), 30-day reoperation (OR, 1.614; 95% CI, 1.278-2.037; p < 0.001), and 30-day mortality (OR, 3.337; 95% CI, 1.213-9.180; p = 0.020). Patients with infected TKA had higher rates of postoperative infection (OR, 3.818; 95% CI, 3.082-4.728; p < 0.001), renal failure (OR, 36.709; 95% CI, 8.255-163.231; p < 0.001), sepsis (OR, 7.582; 95% CI, 5.529-10.397; p < 0.001), and septic shock (OR, 3.031; 95% CI, 1.376-6.675; p = 0.006).

Conclusions Policymakers should be aware of the higher rate of mortality, readmissions, reoperations, and complications in patients with infected TKA. Without appropriate risk adjustment or excluding these patients all together from alternative payment and quality reporting models, fewer providers will be incentivized to care for patients with infected TKA.

Level of Evidence Level III, therapeutic study.

P. M. Courtney, Rothman Institute, Department of Orthopaedic Surgery, Thomas Jefferson University Hospital, Philadelphia, PA, USA

A. J. Boniello, Department of Orthopaedic Surgery, Drexel University College of Medicine, Philadelphia, PA, USA

C. J. Della Valle, Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, IL, USA

G.-C. Lee, Department of Orthopaedic Surgery, University of Pennsylvania School of Medicine, Penn Presbyterian Medical Center, Philadelphia, PA, USA

P. M. Courtney, Assistant Professor of Orthopaedic Surgery, Thomas Jefferson University Hospital, Rothman Institute, 925 Chestnut Street, 5th Floor, Philadelphia, PA 19107, USA, email:

Each author certifies that neither he, nor any member of his immediate family, has funding or commercial associations (consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article.

All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request.

Clinical Orthopaedics and Related Research® neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDA approval status, of any drug or device before clinical use.

This work was performed at Thomas Jefferson University Hospital, Rothman Institute, Philadelphia, PA, USA.

The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) and the hospitals participating in the ACS NSQIP are the source of the data used herein; they have not verified and are not responsible for the statistical validity of the data analysis or the conclusions derived by the authors.

Received August 31, 2017

Received in revised form November 20, 2017

Accepted November 30, 2017

© 2018 Lippincott Williams & Wilkins LWW
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