Mortality, Cost, and Health Outcomes of Total Knee Arthroplasty in Medicare Patients

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Abstract

There are little data that quantify the long term costs, mortality, and downstream disease after Total Knee Arthroplasty (TKA). The purpose of this study is to compare differences in cost and health outcomes between Medicare patients with OA who undergo TKA and those who avoid the procedure. The Medicare 5% sample was used to identify patients diagnosed with OA during 1997–2009. All OA patients were separated into non-arthroplasty and arthroplasty groups. Differences in costs, mortality, and new disease diagnoses were adjusted using logistic regression for age, sex, race, buy-in status, region, and Charlson score. The 7-year cumulative average Medicare payments for all treatments were $63,940 for the non-TKA group and $83,783 for the TKA group. The risk adjusted mortality hazard ratio (HR) of the TKA group ranged from 0.48 to 0.54 through seven years (all P < 0.001). The risk of heart failure in the TKA group was 40.9% at 7 years (HR = 0.93, P < 0.001). The results demonstrate the patients in the TKA cohort as having a lower probability of heart failure and mortality, at a total incremental cost of $19,843.

Section snippets

Materials and Methods

The Medicare 5% Limited Data Set (LDS) sample was used to identify patients with OA of the knee during the period of 1997 to 2009. Knee osteoarthritis patients were identified using ICD-9 codes within the 715.X6 family. The OA code was required to be the principal diagnosis and occur more than once during a 12 month period to be included in the study. Patients were recruited continuously during the study period and followed until the end of the study period (December 31, 2009), until their

Results

Results are presented for patients who had available 1, 3, 5, and 7 years of follow-up data. The study included 134,458 patients with at least one year of follow-up of whom 53,829 received TKA and the remaining 80,629 patients did not have TKA. The number of patients with 7-year follow up was 39,183 in the non-TKA and 25,904 in the TKA group. The demographic characteristics for both groups are shown in Fig. 1. Fig. 2 shows survival analysis curves for time between diagnosis of OA and surgery.

Discussion

This study, the first of its kind as far as we are aware, evaluates cost and disease burden for Medicare patients with osteoarthritis (OA) of the knee. The analysis of the 5% Medicare sample demonstrated that patients with OA of the knee who underwent TKA had a mortality risk that was approximately half that of the non-TKA group. There was also a reduction of new diagnoses of heart failure at 3, 5, and 7 years after surgery. The study was a broad population-based observational analysis across a

Acknowledgment

The authors would like to thank Javad Parvizi, MD, for assistance in the critical analysis of the study and preparation of the manuscript. The authors would also like to thank Biomet, Inc., for institutional support pertaining to this study.

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    The Conflict of Interest statement associated with this article can be found at http://dx.doi.org/10.1016/j.arth.2012.06.036.

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