Predictors of the placebo response in functional dyspepsia.
BACKGROUND
Trials in functional dyspepsia report placebo response rates of 30% to 40%.


OBJECTIVE
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.


CONCLUSIONS
In functional dyspepsia, a consistent predominant symptom pattern and lower body mass index may be associated with a lower placebo response rate.
Clinical Enteric Neuroscience, Translational and Epidemiological Research Program (CENTER), Mayo Clinic College of Medicine, Rochester, MN 55905, USA. talley.nicholas@mayo.edu
N J
NJ
Talley
G R
GR
Locke
B D
BD
Lahr
A R
AR
Zinsmeister
M
M
Cohard-Radice
T V
TV
D'Elia
J
J
Tack
D L
DL
Earnest
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D004311:Double-Blind Method; D004415:Dyspepsia / Q000188:drug therapy* / Q000503:physiopathology; D005260:Female; D005746:Gastric Emptying / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015990:Placebo Effect; D010919:Placebos / Q000627:therapeutic use*; D011788:Quality of Life; D012720:Severity of Illness Index; D016896:Treatment Outcome
D010919:Placebos