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Comparison of Comorbidity Scores in Predicting Surgical Outcomes

Mehta, Hemalkumar B. PhD*; Dimou, Francesca MD*,†; Adhikari, Deepak MS*; Tamirisa, Nina P. MD*; Sieloff, Eric BS*; Williams, Taylor P. BA*; Kuo, Yong-Fang PhD; Riall, Taylor S. MD, PhD, FACS§

doi: 10.1097/MLR.0000000000000465
Original Articles

Introduction: The optimal methodology for assessing comorbidity to predict various surgical outcomes such as mortality, readmissions, complications, and failure to rescue (FTR) using claims data has not been established.

Objective: Compare diagnosis-based and prescription-based comorbidity scores for predicting surgical outcomes.

Methods: We used 100% Texas Medicare data (2006–2011) and included patients undergoing coronary artery bypass grafting, pulmonary lobectomy, endovascular repair of abdominal aortic aneurysm, open repair of abdominal aortic aneurysm, colectomy, and hip replacement (N=39,616). The ability of diagnosis-based [Charlson comorbidity score, Elixhauser comorbidity score, Combined Comorbidity Score, Centers for Medicare and Medicaid Services-Hierarchical Condition Categories (CMS-HCC)] versus prescription-based Chronic disease score in predicting 30-day mortality, 1-year mortality, 30-day readmission, complications, and FTR were compared using c-statistics (c) and integrated discrimination improvement (IDI).

Results: The overall 30-day mortality was 5.8%, 1-year mortality was 17.7%, 30-day readmission was 14.1%, complication rate was 39.7%, and FTR was 14.5%. CMS-HCC performed the best in predicting surgical outcomes (30-d mortality, c=0.797, IDI=4.59%; 1-y mortality, c=0.798, IDI=9.60%; 30-d readmission, c=0.630, IDI=1.27%; complications, c=0.766, IDI=9.37%; FTR, c=0.811, IDI=5.24%) followed by Elixhauser comorbidity index/disease categories (30-d mortality, c=0.750, IDI=2.37%; 1-y mortality, c=0.755, IDI=5.82%; 30-d readmission, c=0.629, IDI=1.43%; complications, c=0.730, IDI=3.99%; FTR, c=0.749, IDI=2.17%). Addition of prescription-based scores to diagnosis-based scores did not improve performance.

Conclusions: The CMS-HCC had superior performance in predicting surgical outcomes. Prescription-based scores, alone or in addition to diagnosis-based scores, were not better than any diagnosis-based scoring system.

Supplemental Digital Content is available in the text.

*Department of Surgery, The University of Texas Medical Branch, Galveston, TX

Department of Surgery, The University of South Florida, Tampa, FL

Department of Preventive Medicine and Community Health, The University of Texas Medical Branch, Galveston, TX

§Department of Surgery, University of Arizona, Tucson, AZ

Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Website,

Supported by Grants from the UTMB Clinical and Translational Science Award # UL1TR000071, NIH T-32 Grant # 5T32DK007639, and AHRQ Grant # 1R24HS022134.

The authors declare no conflict of interest.

Reprints: Hemalkumar B. Mehta, PhD, Department of Surgery, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0541. E-mail:

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