title: Systematic review of peptic ulcer disease incidence rates: do studies without validation provide reliable estimates?
abstract: OBJECTIVE
  Incidence rate (IR) estimates for peptic ulcer disease (PUD) vary widely among studies. We conducted a systematic review to quantify and examine the discrepancies.
  
  
  METHODS
  Of 4780 articles identified from PubMed and EMBASE databases, 31 published in the last three decades that had reported IRs of PUD in the general population were included. Random effects meta-analysis and meta-regression were performed to calculate pooled estimates and to identify sources of heterogeneity.
  
  
  RESULTS
  The pooled IR estimate per 1000 person-years was 0.90 (95% confidence interval: 0.78-1.04) for uncomplicated PUD, 0.57 (0.49-0.65) for peptic ulcer bleeding, 0.10 (0.08-0.13) for gastrointestinal perforations, and 3.18 (2.05-4.92) for nonspecific PUD. Within specific outcomes definitions, IR estimates were significantly lower in studies with restriction to hospitalized cases, case validation, and case ascertainment directly from hospital or clinical sources versus computerized health care databases. Younger age, female sex, and later calendar time were also associated with lower PUD incidence.
  
  
  CONCLUSIONS
  We found that the IR of uncomplicated PUD was in the order of one case per 1000 person-years in the general population, and that the IR of peptic ulcer complications was around 0.7 cases per 1000 person-years. Comparisons of IR estimates among studies need to take into account disease definition and other study characteristics, particularly whether outcome validation was performed in computerized claims. The use of claims to identify PUD cases might overestimate the IR by around 45%.
authors.affiliation: Department of Epidemiology, Harvard School of Public Health, Boston, USA.
authors.forename: Kueiyu Joshua
authors.initials: KJ
authors.lastname: Lin
authors.forename: Luis A
authors.initials: LA
authors.lastname: García Rodríguez
authors.forename: Sonia
authors.initials: S
authors.lastname: Hernández-Díaz
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D016208:Databases, Factual / Q000706:statistics & numerical data; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000379:methods*; D010437:Peptic Ulcer / Q000453:epidemiology* / Q000473:pathology; D012044:Regression Analysis; D012307:Risk Factors; D012737:Sex Factors; D054928:Validation Studies as Topic