title: Validity of Diagnostic Codes for Acute Stroke in Administrative Databases: A Systematic Review.
abstract: OBJECTIVE
  To conduct a systematic review of studies reporting on the validity of International Classification of Diseases (ICD) codes for identifying stroke in administrative data.
  
  
  METHODS
  MEDLINE and EMBASE were searched (inception to February 2015) for studies: (a) Using administrative data to identify stroke; or (b) Evaluating the validity of stroke codes in administrative data; and (c) Reporting validation statistics (sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), or Kappa scores) for stroke, or data sufficient for their calculation. Additional articles were located by hand search (up to February 2015) of original papers. Studies solely evaluating codes for transient ischaemic attack were excluded. Data were extracted by two independent reviewers; article quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies tool.
  
  
  RESULTS
  Seventy-seven studies published from 1976-2015 were included. The sensitivity of ICD-9 430-438/ICD-10 I60-I69 for any cerebrovascular disease was ≥ 82% in most [≥ 50%] studies, and specificity and NPV were both ≥ 95%. The PPV of these codes for any cerebrovascular disease was ≥ 81% in most studies, while the PPV specifically for acute stroke was ≤ 68%. In at least 50% of studies, PPVs were ≥ 93% for subarachnoid haemorrhage (ICD-9 430/ICD-10 I60), 89% for intracerebral haemorrhage (ICD-9 431/ICD-10 I61), and 82% for ischaemic stroke (ICD-9 434/ICD-10 I63 or ICD-9 434&436). For in-hospital deaths, sensitivity was 55%. For cerebrovascular disease or acute stroke as a cause-of-death on death certificates, sensitivity was ≤ 71% in most studies while PPV was ≥ 87%.
  
  
  CONCLUSIONS
  While most cases of prevalent cerebrovascular disease can be detected using 430-438/I60-I69 collectively, acute stroke must be defined using more specific codes. Most in-hospital deaths and death certificates with stroke as a cause-of-death correspond to true stroke deaths. Linking vital statistics and hospitalization data may improve the ascertainment of fatal stroke.
authors: Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada; Arthritis Research Canada, Richmond, British Columbia, Canada.
authors: Natalie
authors: N
authors: McCormick
authors: Arthritis Research Canada, Richmond, British Columbia, Canada.
authors: Vidula
authors: V
authors: Bhole
authors: Arthritis Research Canada, Richmond, British Columbia, Canada; Division of Rheumatology, Department of Medicine. University of British Columbia, Vancouver, British Columbia, Canada; Cardiovascular Committee of the CANRAD Network, Richmond, British Columbia, Canada.
authors: Diane
authors: D
authors: Lacaille
authors: Arthritis Research Canada, Richmond, British Columbia, Canada; Division of Rheumatology, Department of Medicine. University of British Columbia, Vancouver, British Columbia, Canada; Cardiovascular Committee of the CANRAD Network, Richmond, British Columbia, Canada.
authors: J Antonio
authors: JA
authors: Avina-Zubieta
mesh_terms: D002543:Cerebral Hemorrhage / Q000175:diagnosis / Q000473:pathology; D002561:Cerebrovascular Disorders / Q000175:diagnosis / Q000473:pathology; D059019:Clinical Coding / Q000379:methods; D016208:Databases, Factual; D003644:Death Certificates; D006760:Hospitalization; D006801:Humans; D038801:International Classification of Diseases; D002546:Ischemic Attack, Transient / Q000175:diagnosis / Q000473:pathology; D020521:Stroke / Q000175:diagnosis* / Q000473:pathology*; D013345:Subarachnoid Hemorrhage / Q000175:diagnosis / Q000473:pathology