title: Effects of cardiovascular comorbidity adjustment on SRTR risk-adjusted cox proportional hazard models of graft survival.
abstract: BACKGROUND
  The Scientific Registry of Transplant Recipients (SRTR) and the Centers for Medicare and Medicaid Services (CMS) determine expected graft survivals to identify potentially underperforming transplant centers. There has been recent interest in evaluating adjustments for comorbidities when performing these calculations. This study was performed to determine the influence that adjustment for pre-transplant cardiovascular disease comorbidity can have on risk-adjusted Cox models, such as those used by SRTR and CMS.
  
  
  METHODS
  We analyzed Cox proportional hazards models for 1-year and 3-year graft survival for kidney recipients from a single center where cardiovascular disease covariates were added to a baseline model derived by using the SRTR calculated risk scores and including all standard SRTR parameters.
  
  
  RESULTS
  Living and deceased donor recipient 1-year and living donor 3-year Cox models that included all seven covariates demonstrated 8% to 13% improved discrimination. Only the 1-year deceased donor recipient Cox model demonstrated significantly improved calibration (likelihood ratio test P=0.038). The expected graft losses increased by >30% for living donor recipients at 1 and 3 years and decreased by 2% to 4% for deceased donor recipients at 1 and 3 years.
  
  
  CONCLUSIONS
  SRTR and CMS use of pre-transplant cardiovascular comorbidity adjustment might impact center performance evaluations.
authors.affiliation: 1 Division of Transplantation, Department of Surgery, The Ohio State University, Columbus, OH. 2 Ohio State University Center for Biostatistics, Columbus, OH. 3 Division of Nephrology, Department of Medicine, The Ohio State University, Columbus, OH. 4 Address correspondence to: Ronald P. Pelletier, M.D., 395 West 12th Avenue, Columbus, Ohio 43210.
authors.forename: Ronald P
authors.initials: RP
authors.lastname: Pelletier
authors.forename: Gary S
authors.initials: GS
authors.lastname: Phillips
authors.forename: Amer
authors.initials: A
authors.lastname: Rajab
authors.forename: Todd E
authors.initials: TE
authors.lastname: Pesavento
authors.forename: Mitchell L
authors.initials: ML
authors.lastname: Henry
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002318:Cardiovascular Diseases / Q000453:epidemiology* / Q000401:mortality; D014487:Centers for Medicare and Medicaid Services, U.S.; D015897:Comorbidity; D005260:Female; D006085:Graft Survival; D006801:Humans; D016030:Kidney Transplantation / Q000009:adverse effects* / Q000401:mortality; D016013:Likelihood Functions; D019520:Living Donors; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D019984:Quality Indicators, Health Care; D012042:Registries; D012307:Risk Factors; D013997:Time Factors; D009927:Tissue and Organ Procurement; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology; D055815:Young Adult