title: Validity of claims-based stroke algorithms in contemporary Medicare data: reasons for geographic and racial differences in stroke (REGARDS) study linked with medicare claims.
abstract: BACKGROUND
  The accuracy of stroke diagnosis in administrative claims for a contemporary population of Medicare enrollees has not been studied. We assessed the validity of diagnostic coding algorithms for identifying stroke in the Medicare population by linking data from the REasons for Geographic And Racial Differences in Stroke (REGARDS) Study to Medicare claims.
  
  
  RESULTS
  The REGARDS Study enrolled 30 239 participants ≥45 years in the United States between 2003 and 2007. Stroke experts adjudicated suspected strokes, using retrieved medical records. We linked data for participants enrolled in fee-for-service Medicare to claims files from 2003 through 2009. Using adjudicated strokes as the gold standard, we calculated accuracy measures for algorithms to identify incident and recurrent strokes. We linked data for 15 089 participants, among whom 422 participants had adjudicated strokes during follow-up. An algorithm using primary discharge diagnosis codes for acute ischemic or hemorrhagic stroke (International Classification of Diseases, Ninth Revision, Clinical Modification codes: 430, 431, 433.x1, 434.x1, 436) had a positive predictive value of 92.6% (95% confidence interval, 88.8%-96.4%), a specificity of 99.8% (99.6%-99.9%), and a sensitivity of 59.5% (53.8%-65.1%). An algorithm using only acute ischemic stroke codes (433.x1, 434.x1, 436) had a positive predictive value of 91.1% (95% confidence interval, 86.6%-95.5%), a specificity of 99.8% (99.7%-99.9%), and a sensitivity of 58.6% (52.4%-64.7%).
  
  
  CONCLUSIONS
  Claims-based algorithms to identify stroke in a contemporary Medicare cohort had high positive predictive value and specificity, supporting their use as outcomes for etiologic and comparative effectiveness studies in similar populations. These inpatient algorithms are unsuitable for estimating stroke incidence because of low sensitivity.
authors: From the Department of Epidemiology, Harvard School of Public Health, Boston, MA (H.K.); Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women's Hospital and Harvard Medical School, Boston, MA (H.K., J.J.J.); Department of Biostatistics (S.E.J., J.D.R., G.H.) and Department of Epidemiology (J.R.C.), University of Alabama at Birmingham School of Public Health; Department of Medicine, University of Alabama at Birmingham School of Medicine (J.R.C., R.R., M.M.S.); Duke Clinical Research Institute, Department of Medicine, Duke University School of Medicine, Durham, NC (N.C.H., S.S.); Department of Neurology, University of Cincinnati, OH (B.M.K.); and Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.).
authors: Hiraku
authors: H
authors: Kumamaru
authors: From the Department of Epidemiology, Harvard School of Public Health, Boston, MA (H.K.); Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women's Hospital and Harvard Medical School, Boston, MA (H.K., J.J.J.); Department of Biostatistics (S.E.J., J.D.R., G.H.) and Department of Epidemiology (J.R.C.), University of Alabama at Birmingham School of Public Health; Department of Medicine, University of Alabama at Birmingham School of Medicine (J.R.C., R.R., M.M.S.); Duke Clinical Research Institute, Department of Medicine, Duke University School of Medicine, Durham, NC (N.C.H., S.S.); Department of Neurology, University of Cincinnati, OH (B.M.K.); and Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.).
authors: Suzanne E
authors: SE
authors: Judd
authors: From the Department of Epidemiology, Harvard School of Public Health, Boston, MA (H.K.); Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women's Hospital and Harvard Medical School, Boston, MA (H.K., J.J.J.); Department of Biostatistics (S.E.J., J.D.R., G.H.) and Department of Epidemiology (J.R.C.), University of Alabama at Birmingham School of Public Health; Department of Medicine, University of Alabama at Birmingham School of Medicine (J.R.C., R.R., M.M.S.); Duke Clinical Research Institute, Department of Medicine, Duke University School of Medicine, Durham, NC (N.C.H., S.S.); Department of Neurology, University of Cincinnati, OH (B.M.K.); and Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.).
authors: Jeffrey R
authors: JR
authors: Curtis
authors: From the Department of Epidemiology, Harvard School of Public Health, Boston, MA (H.K.); Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women's Hospital and Harvard Medical School, Boston, MA (H.K., J.J.J.); Department of Biostatistics (S.E.J., J.D.R., G.H.) and Department of Epidemiology (J.R.C.), University of Alabama at Birmingham School of Public Health; Department of Medicine, University of Alabama at Birmingham School of Medicine (J.R.C., R.R., M.M.S.); Duke Clinical Research Institute, Department of Medicine, Duke University School of Medicine, Durham, NC (N.C.H., S.S.); Department of Neurology, University of Cincinnati, OH (B.M.K.); and Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.).
authors: Rekha
authors: R
authors: Ramachandran
authors: From the Department of Epidemiology, Harvard School of Public Health, Boston, MA (H.K.); Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women's Hospital and Harvard Medical School, Boston, MA (H.K., J.J.J.); Department of Biostatistics (S.E.J., J.D.R., G.H.) and Department of Epidemiology (J.R.C.), University of Alabama at Birmingham School of Public Health; Department of Medicine, University of Alabama at Birmingham School of Medicine (J.R.C., R.R., M.M.S.); Duke Clinical Research Institute, Department of Medicine, Duke University School of Medicine, Durham, NC (N.C.H., S.S.); Department of Neurology, University of Cincinnati, OH (B.M.K.); and Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.).
authors: N Chantelle
authors: NC
authors: Hardy
authors: From the Department of Epidemiology, Harvard School of Public Health, Boston, MA (H.K.); Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women's Hospital and Harvard Medical School, Boston, MA (H.K., J.J.J.); Department of Biostatistics (S.E.J., J.D.R., G.H.) and Department of Epidemiology (J.R.C.), University of Alabama at Birmingham School of Public Health; Department of Medicine, University of Alabama at Birmingham School of Medicine (J.R.C., R.R., M.M.S.); Duke Clinical Research Institute, Department of Medicine, Duke University School of Medicine, Durham, NC (N.C.H., S.S.); Department of Neurology, University of Cincinnati, OH (B.M.K.); and Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.).
authors: J David
authors: JD
authors: Rhodes
authors: From the Department of Epidemiology, Harvard School of Public Health, Boston, MA (H.K.); Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women's Hospital and Harvard Medical School, Boston, MA (H.K., J.J.J.); Department of Biostatistics (S.E.J., J.D.R., G.H.) and Department of Epidemiology (J.R.C.), University of Alabama at Birmingham School of Public Health; Department of Medicine, University of Alabama at Birmingham School of Medicine (J.R.C., R.R., M.M.S.); Duke Clinical Research Institute, Department of Medicine, Duke University School of Medicine, Durham, NC (N.C.H., S.S.); Department of Neurology, University of Cincinnati, OH (B.M.K.); and Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.).
authors: Monika M
authors: MM
authors: Safford
authors: From the Department of Epidemiology, Harvard School of Public Health, Boston, MA (H.K.); Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women's Hospital and Harvard Medical School, Boston, MA (H.K., J.J.J.); Department of Biostatistics (S.E.J., J.D.R., G.H.) and Department of Epidemiology (J.R.C.), University of Alabama at Birmingham School of Public Health; Department of Medicine, University of Alabama at Birmingham School of Medicine (J.R.C., R.R., M.M.S.); Duke Clinical Research Institute, Department of Medicine, Duke University School of Medicine, Durham, NC (N.C.H., S.S.); Department of Neurology, University of Cincinnati, OH (B.M.K.); and Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.).
authors: Brett M
authors: BM
authors: Kissela
authors: From the Department of Epidemiology, Harvard School of Public Health, Boston, MA (H.K.); Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women's Hospital and Harvard Medical School, Boston, MA (H.K., J.J.J.); Department of Biostatistics (S.E.J., J.D.R., G.H.) and Department of Epidemiology (J.R.C.), University of Alabama at Birmingham School of Public Health; Department of Medicine, University of Alabama at Birmingham School of Medicine (J.R.C., R.R., M.M.S.); Duke Clinical Research Institute, Department of Medicine, Duke University School of Medicine, Durham, NC (N.C.H., S.S.); Department of Neurology, University of Cincinnati, OH (B.M.K.); and Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.).
authors: George
authors: G
authors: Howard
authors: From the Department of Epidemiology, Harvard School of Public Health, Boston, MA (H.K.); Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women's Hospital and Harvard Medical School, Boston, MA (H.K., J.J.J.); Department of Biostatistics (S.E.J., J.D.R., G.H.) and Department of Epidemiology (J.R.C.), University of Alabama at Birmingham School of Public Health; Department of Medicine, University of Alabama at Birmingham School of Medicine (J.R.C., R.R., M.M.S.); Duke Clinical Research Institute, Department of Medicine, Duke University School of Medicine, Durham, NC (N.C.H., S.S.); Department of Neurology, University of Cincinnati, OH (B.M.K.); and Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.).
authors: Jessica J
authors: JJ
authors: Jalbert
authors: From the Department of Epidemiology, Harvard School of Public Health, Boston, MA (H.K.); Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women's Hospital and Harvard Medical School, Boston, MA (H.K., J.J.J.); Department of Biostatistics (S.E.J., J.D.R., G.H.) and Department of Epidemiology (J.R.C.), University of Alabama at Birmingham School of Public Health; Department of Medicine, University of Alabama at Birmingham School of Medicine (J.R.C., R.R., M.M.S.); Duke Clinical Research Institute, Department of Medicine, Duke University School of Medicine, Durham, NC (N.C.H., S.S.); Department of Neurology, University of Cincinnati, OH (B.M.K.); and Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.).
authors: Thomas G
authors: TG
authors: Brott
authors: From the Department of Epidemiology, Harvard School of Public Health, Boston, MA (H.K.); Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women's Hospital and Harvard Medical School, Boston, MA (H.K., J.J.J.); Department of Biostatistics (S.E.J., J.D.R., G.H.) and Department of Epidemiology (J.R.C.), University of Alabama at Birmingham School of Public Health; Department of Medicine, University of Alabama at Birmingham School of Medicine (J.R.C., R.R., M.M.S.); Duke Clinical Research Institute, Department of Medicine, Duke University School of Medicine, Durham, NC (N.C.H., S.S.); Department of Neurology, University of Cincinnati, OH (B.M.K.); and Department of Neurology, Mayo Clinic, Jacksonville, FL (T.G.B.). soko.setoguchi@duke.edu.
authors: Soko
authors: S
authors: Setoguchi
mesh_terms: D000368:Aged; D000465:Algorithms; D018588:Fee-for-Service Plans / Q000191:economics*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007345:Insurance Claim Review / Q000706:statistics & numerical data*; D008297:Male; D008499:Medical Records / Q000706:statistics & numerical data*; D006278:Medicare / Q000706:statistics & numerical data*; D044469:Racial Groups; D015203:Reproducibility of Results; D012189:Retrospective Studies; D020521:Stroke / Q000191:economics* / Q000208:ethnology; D014481:United States / Q000453:epidemiology
keywords: Medicare; cohort studies; comparative effectiveness research, diagnosis; health services research