title: Identification of Helicobacter pylori infected patients, using administrative data.
abstract: BACKGROUND
  Helicobacter pylori is a prevalent organism implicated in peptic ulcer disease.
  
  
  OBJECTIVE
  To validate administrative data for diagnosis of H. pylori-infected patients.
  
  
  METHODS
  Administrative data identified patients with ICD-9 code for H. pylori (041.86) or prescription of eradication therapy; diagnosis was confirmed by chart abstraction. Multivariable regression assessed predictors of infection considering drug therapy, ICD-9 code 041.86, procedure code, in-patient or out-patient diagnostic code, age, gender and race to generate an algorithm for validation.
  
  
  RESULTS
  The test cohort of 531 patients (361 potential cases; 170 random controls) was primarily male (94%), Caucasian (59%) and elderly [67 years (s.d. 10)]. The positive predictive value (PPV) of ICD-9 code 041.86 was 100% and 97.4% if from an in-patient or out-patient encounter, respectively. Eradication drug therapy had a PPV of 73.7% (triple therapy) and 97.7% (quadruple therapy). The strongest predictors were out-patient ICD-9 code 041.86 (OR 8.1; 95% CI: 7.0-9.1); eradication drug therapy (OR 7.4; 95% CI: 6.6-8.3); oesophagogastroduodenoscopy (OR 3.5; 95% CI: 3.3-3.6); and age > or =70 (OR 1.2; 95% CI: 1.1-1.4). An algorithm including these data elements yielded a c-statistic of 0.93 and PPV of 97.9%.
  
  
  CONCLUSIONS
  Administrative data can diagnose H. pylori-infected patients. The diagnostic algorithm includes presence of eradication drug therapy overlapping with an out-patient ICD-9 code 041.86 among elderly adults.
authors.affiliation: Houston Center for Quality of Care & Utilization Studies, Section of Health Services Research, Michael E. DeBakey VA Medical Center, Houston, TX 77030, USA.
authors.forename: S
authors.initials: S
authors.lastname: Thirumurthi
authors.forename: R
authors.initials: R
authors.lastname: Desilva
authors.forename: D L
authors.initials: DL
authors.lastname: Castillo
authors.forename: P
authors.initials: P
authors.lastname: Richardson
authors.forename: N S
authors.initials: NS
authors.lastname: Abraham