Waiting list may be a nocebo condition in psychotherapy trials: a contribution from network meta-analysis.
OBJECTIVE
Various control conditions have been employed in psychotherapy trials, but there is growing suspicion that they may lead to different effect size estimates. The present study aims to examine the differences among control conditions including waiting list (WL), no treatment (NT) and psychological placebo (PP).


METHODS
We comprehensively searched for all randomized controlled trials (RCTs) comparing cognitive-behaviour therapies (CBT) against various control conditions in the acute phase treatment of depression, and applied network meta-analysis (NMA) to combine all direct and indirect comparisons among the treatment and control arms.


RESULTS
We identified 49 RCTs (2730 participants) comparing WL, NT, PP and CBT. This network of evidence was consistent, and the effect size estimates for CBT were substantively different depending on the control condition. The odds ratio of response for NT over WL was statistically significant at 2.9 (95% CI: 1.3-5.7). However, the quality of evidence, including publication bias, was less than ideal and none of the preplanned sensitivity analyses limiting to high-quality studies could be conducted, while findings of significant differences did not persist in post hoc sensitivity analyses trying to adjust for publication bias.


CONCLUSIONS
There may be important differences in control conditions currently used in psychotherapy trials.
Departments of Health Promotion and Human Behavior and of Clinical Epidemiology, Kyoto University Graduate School of Medicine/School of Public Health, Kyoto, Japan.
T A
TA
Furukawa
H
H
Noma
D M
DM
Caldwell
M
M
Honyashiki
K
K
Shinohara
H
H
Imai
P
P
Chen
V
V
Hunot
R
R
Churchill
D000328:Adult; D015928:Cognitive Behavioral Therapy / Q000592:standards*; D003863:Depression / Q000628:therapy*; D003865:Major Depressive Disorder / Q000628:therapy*; D006801:Humans; D064786:Nocebo Effect; D010919:Placebos; D016032:Randomized Controlled Trials as Topic / Q000592:standards*; D014850:Waiting Lists
D010919:Placebos
clinical trials; cognitive therapy; control groups; placebo; waiting lists