title: INTERMACS profiles and modifiers: Heterogeneity of patient classification and the impact of modifiers on predicting patient outcome.
abstract: BACKGROUND
  Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) patient profiles and modifiers are descriptors of patient illness severity before durable ventricular assist device implantation. It is unknown how individual U.S. institutions and practitioners assign profiles and if modifiers improve on risk discrimination.
  
  
  METHODS
  Respondents (n = 212) to a web-based survey answered questions about the INTERMACS profile assignment process in their institution. For 5 hypothetical clinical scenarios, respondents assigned the best profile. The INTERMACS registry (2009-2014) was queried, and hazard ratio (HR) (95% confidence interval [CI]) for mortality between profiles as well as based on the presence of temporary circulatory support (TCS), frequent flyer (FF), or arrhythmia modifiers was calculated.
  
  
  RESULTS
  Respondents included 131 (62%) cardiologists, 30 (14%) surgeons, and 51 (24%) physician extenders/coordinators. Institutional INTERMACS profile assignment was variable (63% assigned by cardiologists/surgeons; 10% by research coordinators; 27% by physician extenders). Profile assignments in hypothetical patient scenarios were heterogeneous, especially for contiguous profiles. The 1-year survivals for Profiles 1, 2, and 3 were 77 ± 1.2%, 80 ± 0.7%, and 84 ± 0.7% (p < 0.001). Although Profile 1 patients had worse adjusted survival than Profile 3 patients (p = 0.001), survival for Profile 1 patients vs Profile 2 patients was similar (adjusted HR = 1.01 [95% CI = 0.88-1.12]). The TCS (adjusted HR = 1.1 [95% CI = 0.94-1.2]) and arrhythmia (adjusted HR = 1.1 [95% CI = 0.97-1.2]) modifiers were not predictive of mortality, but the FF modifier was (HR = 1.3 [95% CI = 1.02-1.63]).
  
  
  CONCLUSIONS
  Substantial heterogeneity exists in the process and assignment of INTERMACS profiles. This heterogeneity could affect mortality estimates used for risk stratification. Only the FF modifier appears to improve risk discrimination beyond that of known risk factors. Adding objective descriptors may reduce profile heterogeneity.
authors.affiliation: Department of Cardiovascular Medicine, St Vincent Heart Center of Indiana, Indianapolis, Indiana. Electronic address: jennifer.cowger@stvincent.org.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Cowger
authors.affiliation: Department of Cardiovascular Medicine, Inova Heart and Vascular Institute, Falls Church, Virginia.
authors.forename: Palak
authors.initials: P
authors.lastname: Shah
authors.affiliation: Division of Cardiothoracic Surgery, Mayo Clinic, Rochester, Minnesota.
authors.forename: John
authors.initials: J
authors.lastname: Stulak
authors.affiliation: Division of Cardiothoracic Surgery, Mayo Clinic, Rochester, Minnesota.
authors.forename: Simon
authors.initials: S
authors.lastname: Maltais
authors.affiliation: Department of Cardiovascular Medicine, University of Michigan Health System, Ann Arbor, Michigan.
authors.forename: Keith D
authors.initials: KD
authors.lastname: Aaronson
authors.affiliation: Division of Cardiothoracic Surgery, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: James K
authors.initials: JK
authors.lastname: Kirklin
authors.affiliation: Department of Cardiac Surgery, University of Michigan Health System, Ann Arbor, Michigan.
authors.forename: Francis D
authors.initials: FD
authors.lastname: Pagani
authors.affiliation: Division of Cardiothroacic Surgery, St Vincent Heart Center of Indiana, Indianapolis, Indiana.
authors.forename: Christopher
authors.initials: C
authors.lastname: Salerno
mesh_terms: D005500:Follow-Up Studies; D006333:Heart Failure / Q000401:mortality / Q000628:therapy*; D006353:Heart-Assist Devices; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D015996:Survival Rate / Q000639:trends; D014481:United States / Q000453:epidemiology
keywords: LVAD; mortality; prediction; temporary circulatory support