title: Risk of Stroke After the International Classification of Diseases-Ninth Revision Discharge Code Diagnosis of Hypertensive Encephalopathy.
abstract: OBJECTIVE
  Although chronic hypertension is a well-established risk factor for stroke, little is known about stroke risk after hypertensive encephalopathy (HE), when neurologic sequelae of hypertension become evident. Therefore, we evaluated the risk of stroke after a diagnosis of HE.
  
  
  METHODS
  We identified all patients discharged from California, New York, and Florida emergency departments and acute care hospitals between 2005 and 2012 with a primary International Classification of Diseases, Ninth Edition, Clinical Modification discharge diagnosis of HE (437.2). Patients discharged with a primary diagnosis of seizure (345.x) served as negative controls, whereas patients with a primary diagnosis of transient ischemic attack (435.x) were positive controls. Our primary outcome was the composite of subsequent ischemic stroke or intracerebral hemorrhage. Kaplan-Meier survival statistics were used to calculate cumulative outcome rates, and Cox proportional hazard analysis was used to examine the association between index disease types and outcomes while adjusting for vascular risk factors.
  
  
  RESULTS
  We identified 8233 patients with HE, 191 091 with seizure, and 308 680 with transient ischemic attack. The 1-year cumulative rate of ischemic stroke or intracerebral hemorrhage after HE was 4.90% (95% confidence interval [CI], 4.45-5.40) when compared with 0.92% (95% CI, 0.88-0.97) after seizure and 4.49% (95% CI, 4.42-4.57) after transient ischemic attack. The risk of intracerebral hemorrhage was significantly elevated in those with HE (hazard ratio, 2.0; 95% CI, 1.7-2.5) but not in those with transient ischemic attack (hazard ratio, 1.0; 95% CI, 0.9-1.1), when compared with seizure patients.
  
  
  CONCLUSIONS
  Patients discharged with a diagnosis of HE face a high risk of future cerebrovascular events, particularly intracerebral hemorrhage.
authors.affiliation: From the Department of Neurology (M.P.L., A.E.M., N.S.P., B.B.N., H.K.) and Feil Family Brain and Mind Research Institute (G.G., B.B.N., H.K.), Weill Cornell Medical College, New York, NY. mpl9005@med.cornell.edu.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Lerario
authors.affiliation: From the Department of Neurology (M.P.L., A.E.M., N.S.P., B.B.N., H.K.) and Feil Family Brain and Mind Research Institute (G.G., B.B.N., H.K.), Weill Cornell Medical College, New York, NY.
authors.forename: Alexander E
authors.initials: AE
authors.lastname: Merkler
authors.affiliation: From the Department of Neurology (M.P.L., A.E.M., N.S.P., B.B.N., H.K.) and Feil Family Brain and Mind Research Institute (G.G., B.B.N., H.K.), Weill Cornell Medical College, New York, NY.
authors.forename: Gino
authors.initials: G
authors.lastname: Gialdini
authors.affiliation: From the Department of Neurology (M.P.L., A.E.M., N.S.P., B.B.N., H.K.) and Feil Family Brain and Mind Research Institute (G.G., B.B.N., H.K.), Weill Cornell Medical College, New York, NY.
authors.forename: Neal S
authors.initials: NS
authors.lastname: Parikh
authors.affiliation: From the Department of Neurology (M.P.L., A.E.M., N.S.P., B.B.N., H.K.) and Feil Family Brain and Mind Research Institute (G.G., B.B.N., H.K.), Weill Cornell Medical College, New York, NY.
authors.forename: Babak B
authors.initials: BB
authors.lastname: Navi
authors.affiliation: From the Department of Neurology (M.P.L., A.E.M., N.S.P., B.B.N., H.K.) and Feil Family Brain and Mind Research Institute (G.G., B.B.N., H.K.), Weill Cornell Medical College, New York, NY.
authors.forename: Hooman
authors.initials: H
authors.lastname: Kamel
mesh_terms: D002545:Brain Ischemia / Q000150:complications / Q000453:epidemiology*; D002140:California / Q000453:epidemiology; D016022:Case-Control Studies; D002543:Cerebral Hemorrhage / Q000150:complications / Q000453:epidemiology*; D015331:Cohort Studies; D005260:Female; D005431:Florida / Q000453:epidemiology; D006801:Humans; D006973:Hypertension / Q000453:epidemiology*; D020343:Hypertensive Encephalopathy / Q000453:epidemiology*; D038801:International Classification of Diseases; D002546:Ischemic Attack, Transient / Q000453:epidemiology; D053208:Kaplan-Meier Estimate; D008297:Male; D009518:New York / Q000453:epidemiology; D010351:Patient Discharge; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D012640:Seizures / Q000453:epidemiology; D020521:Stroke / Q000453:epidemiology* / Q000209:etiology
keywords: cerebral hemorrhage; epidemiology; hypertension; hypertensive encephalopathy; risk factors; stroke