title: Systematic review: the methodological quality of trials affects estimates of treatment efficacy in functional (non-ulcer) dyspepsia.
abstract: OBJECTIVE
  To evaluate treatment efficacy using objective quality criteria.
  
  
  METHODS
  A systematic review was performed of randomized controlled trials of endoscopically investigated dyspepsia (1979-2003) using the Jadad score and Rome II guidelines. The Jadad score differentiated studies as 'high quality' (score 4-5/5) vs. 'poor quality' (score 1-3/5). Three key Rome II guidelines on study design (cut-off of 0/3 or > 0/3) were also compared with the Jadad score.
  
  
  RESULTS
  Poor quality trials suggested a benefit of prokinetic therapy [relative risk (RR) of remaining dyspeptic, 0.47; 95% confidence interval (CI), 0.39-0.56), which was not confirmed in high quality trials (RR, 1.0; 95% CI, 0.84-1.19). There was a marked benefit of H2-receptor antagonist therapy in poor quality trials (RR, 0.68; 95% CI, 0.61-0.76), but a marginal benefit in good quality trials (RR, 0.87; 95% CI, 0.79-0.97). Trial quality did not affect the small statistically significant benefit seen with Helicobacter pylori eradication. Two high quality trials suggested a limited benefit with the use of proton pump inhibitors, with no poor quality trials to provide a comparison. Separation of the studies by the Rome II criteria had a similar impact on the calculated treatment estimates.
  
  
  CONCLUSIONS
  The magnitude of benefit of prokinetic and H2-receptor antagonist therapies reported in previous meta-analyses has been over-estimated. The quality of trials has an impact on the efficacy estimates of treatment. The Rome II criteria for study methodology may be appropriate for judging study quality.
authors.affiliation: Sections of Health Services Research and Gastroenterology, Houston Veterans Affairs Medical Center and Baylor College of Medicine, Houston, TX, USA. nabraham@bcm.tmc.edu
authors.forename: N S
authors.initials: NS
authors.lastname: Abraham
authors.forename: P
authors.initials: P
authors.lastname: Moayyedi
authors.forename: B
authors.initials: B
authors.lastname: Daniels
authors.forename: S J O
authors.initials: SJ
authors.lastname: Veldhuyzen Van Zanten
mesh_terms: D004415:Dyspepsia / Q000188:drug therapy*; D005772:Gastrointestinal Transit / Q000187:drug effects*; D016481:Helicobacter Infections / Q000188:drug therapy; D006635:Histamine H2 Antagonists / Q000627:therapeutic use*; D006801:Humans; D054328:Proton Pump Inhibitors; D011613:Psychotherapy / Q000379:methods; D016032:Randomized Controlled Trials as Topic / Q000592:standards*
chemical_list: D006635:Histamine H2 Antagonists; D054328:Proton Pump Inhibitors