title: International Classification of Diseases, 9th Revision, Clinical Modification codes in discharge abstracts are poor measures of complication occurrence in medical inpatients.
abstract: OBJECTIVE
  The authors tested the ability of International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes in discharge abstracts to identify medical inpatients who experienced an in-hospital complication, using complications identified through chart review as the gold standard.
  
  
  METHODS
  Two sets of ICD-9-CM codes were used: an inclusive set including many medical diagnoses that may also be coexistent complicating conditions on admission rather than complications and an exclusive set consisting primarily of ICD-9-CM-specified complication and adverse drug event codes.
  
  
  RESULTS
  Neither set performed well as a diagnostic test for complication occurrence according to receiver operating characteristic analysis (ROC areas were 0.61 for the inclusive set and 0.55 for the exclusive set). Sensitivities of the ICD-9-CM codes for complications were 0.34 for the inclusive set and 0.14 for the exclusive set. Corresponding positive predictive values were 0.32 and 0.37, respectively. Sensitivities of code definitions for individual complications were generally poor, less than 0.5 in most cases.
  
  
  CONCLUSIONS
  The authors conclude that ICD-9-CM codes in discharge abstracts are poor measures of complication occurrence.
authors.affiliation: Houston Center for Quality of Care and Utilization Studies, Houston Veterans Affairs Medical Center, Department of Medicine, Baylor College of Medicine, TX 77030, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Geraci
authors.forename: C M
authors.initials: CM
authors.lastname: Ashton
authors.forename: D H
authors.initials: DH
authors.lastname: Kuykendall
authors.forename: M L
authors.initials: ML
authors.lastname: Johnson
authors.forename: L
authors.initials: L
authors.lastname: Wu
mesh_terms: D000043:Abstracting and Indexing / Q000592:standards*; D015897:Comorbidity; D048909:Diabetes Complications; D004194:Disease / Q000145:classification*; D006333:Heart Failure / Q000150:complications; D006787:Hospitals, Veterans / Q000706:statistics & numerical data*; D006801:Humans; D007049:Iatrogenic Disease / Q000453:epidemiology*; D008173:Lung Diseases, Obstructive / Q000150:complications; D008485:Medical Audit / Q000379:methods; D008499:Medical Records / Q000145:classification*; D010351:Patient Discharge; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014481:United States / Q000453:epidemiology