title: Sensitivity of billing claims for cardiovascular disease events among kidney transplant recipients.
abstract: OBJECTIVE
  Billing claims are increasingly examined beyond administrative functions as outcomes measures in observational research. Few studies have described the performance of billing claims as surrogate measures of clinical events among kidney transplant recipients.
  
  
  METHODS
  We investigated the sensitivity of Medicare billing claims for clinically verified cardiovascular diagnoses (five categories) and procedures (four categories) in a novel database linking Medicare claims to electronic medical records of one transplant program. Cardiovascular events identified in medical records for 571 Medicare-insured transplant recipients in 1991 through 2002 served as reference measures.
  
  
  RESULTS
  Within a claims-ascertainment period spanning +/-30 d of clinically recorded dates, aggregate sensitivity of single claims was higher for case definitions incorporating Medicare Parts A and B for diagnoses and procedures (90.9%) compared with either Part A (82.3%) or Part B (84.6%) alone. Perfect capture of the four procedures was possible within +/-30 d or with short claims window expansion, but sensitivity for the diagnoses trended lower with all study algorithms (91.2% with window up to +/-90 d). Requirement for additional confirmatory diagnosis claims did not appreciably reduce sensitivity. Sensitivity patterns were similar in the early compared with late periods of the study.
  
  
  CONCLUSIONS
  Combined use of Medicare Parts A and B billing claims composes a sensitive measure of cardiovascular events after kidney transplant. Further research is needed to define algorithms that maximize specificity as well as sensitivity of claims from Medicare and other insurers as research measures in this population.
authors.affiliation: Center for Outcomes Research and Division of Nephrology, School of Medicine, Saint Louis University, St. Louis, MO 63104, USA. lentine.krista@stanfordalumni.org
authors.forename: Krista L
authors.initials: KL
authors.lastname: Lentine
authors.forename: Mark A
authors.initials: MA
authors.lastname: Schnitzler
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Abbott
authors.forename: Kosha
authors.initials: K
authors.lastname: Bramesfeld
authors.forename: Paula M
authors.initials: PM
authors.lastname: Buchanan
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Brennan
mesh_terms: D000328:Adult; D000465:Algorithms; D002318:Cardiovascular Diseases / Q000175:diagnosis / Q000453:epidemiology*; D016208:Databases, Factual / Q000592:standards / Q000706:statistics & numerical data; D005568:Forms and Records Control / Q000592:standards / Q000706:statistics & numerical data; D006801:Humans; D007344:Insurance Claim Reporting / Q000592:standards / Q000706:statistics & numerical data*; D007676:Kidney Failure, Chronic / Q000453:epidemiology* / Q000601:surgery; D016030:Kidney Transplantation / Q000706:statistics & numerical data*; D016344:Medicare Part A / Q000592:standards / Q000706:statistics & numerical data*; D016345:Medicare Part B / Q000592:standards / Q000706:statistics & numerical data*; D008962:Models, Theoretical; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014481:United States