title: Veterans health administration information systems as a resource for rare disorders research: Creutzfeldt-Jakob disease as a paradigm.
abstract: OBJECTIVE
  To illustrate the application of Veterans Health Administration (VHA) information systems in both clinical and epidemiologic investigations of a rare disease, our specific aims were: (1) to determine the number and incidence of Creutzfeldt-Jakob disease (CJD) diagnoses in the VHA from fiscal year (FY) 1997 through FY 2010 and (2) to describe the relevant clinical features associated with those diagnoses.
  
  
  METHODS
  The VHA Medical SAS Datasets were queried for all unique, incident CJD diagnoses between FY 1997 and 2010. Electronic health records were then reviewed to validate diagnoses using modified criteria.
  
  
  RESULTS
  During the study period, 115 CJD diagnoses (43 definite, 27 probable, 19 possible, and 26 suspected) were identified. Annual incidence ranged between 0.8 per million (95% CI, 0.3-1.7) in FY 2009 and 3.7 per million (95% CI, 2.1-6.4) in FY 1997. Dementia was documented in 111 cases (96.5%) and myoclonus in 73 (63.5%). Discharges consistent with CJD were noted in 31 of 78 patients (39.7%) with documented electroencephalography.
  
  
  CONCLUSIONS
  For certain rare diseases, VHA information systems can be used to assemble a substantive case series for clinical study. However, the VHA's distinctive demographic characteristics and population dynamics may limit the external validity of epidemiologic investigations.
authors.affiliation: Department of Neurology, Veterans Affairs Medical Center, 950 Campbell Avenue, West Haven, CT 06516, USA.
authors.forename: Jed A
authors.initials: JA
authors.lastname: Barash
authors.forename: Rani A
authors.initials: RA
authors.lastname: Desai
authors.forename: Huned S
authors.initials: HS
authors.lastname: Patwa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D007562:Creutzfeldt-Jakob Syndrome / Q000175:diagnosis* / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D035583:Rare Diseases; D012189:Retrospective Studies; D014481:United States / Q000453:epidemiology; D014493:United States Department of Veterans Affairs; D014728:Veterans / Q000706:statistics & numerical data*; D058014:Veterans Health