Predictors of the placebo response in functional dyspepsia
N J Talley, G R Locke, B D Lahr, A R Zinsmeister, M Cohard-Radice, T V D'Elia, J Tack, D L Earnest, N J Talley, G R Locke, B D Lahr, A R Zinsmeister, M Cohard-Radice, T V D'Elia, J Tack, D L Earnest
Abstract
Background: Trials in functional dyspepsia report placebo response rates of 30% to 40%.
Aim: We aimed to identify predictors of the placebo response.
Methods: Patients from primary, secondary and tertiary practices with functional dyspepsia defined by Rome II criteria were enrolled into one of four clinical trials; 220 patients were randomized to receive placebo. Scintigraphic assessment of gastric emptying at baseline was repeated at the end of the treatment in those with delayed emptying. After a 2 week run-in period, patients were followed for 8 weeks on placebo. Response was assessed on a weekly basis and a responder was defined as satisfactory relief of meal-related symptoms on at least 50% of weeks.
Results: The mean age was 44 years (range 18-82) and 74% were female; 76 (35%) were placebo responders. The predominant symptom was an unstable measure over the trial. Independent predictors of a lower placebo response were lower body mass index and a more consistent predominant symptom pattern (both P < 0.05). No association was seen with age, gender, centre type, baseline symptom score, baseline or change in gastric emptying, or baseline quality of life.
Conclusion: In functional dyspepsia, a consistent predominant symptom pattern and lower body mass index may be associated with a lower placebo response rate.
Source: PubMed