In 37 randomised trials, CBT for OCD beat placebo with an effect size of 1.33 and medication by 0.55
A meta-analysis of every Y-BOCS trial from 1993 to 2014: CBT beat waiting lists (1.31) and placebo (1.33). Exposure with or without a cognitive component made no difference (0.07). Adding medication to CBT did not help significantly.
Reasonable evidence with real limitations. how we score evidence
Caveat on this rating: The very large effects are against waiting lists and placebo, the weakest comparators; the authors themselves list methodological problems in the trials. This analysis found no significant gain from adding medication to CBT, which is the opposite lean from the 54-trial network meta-analysis; the disagreement is unresolved.
The second large synthesis of OCD therapy trials, built differently from the network analysis and landing in the same place.
Significant findings
Ost, Havnen, Hansen and Kvale pooled all 37 randomised trials of cognitive behaviour therapy for OCD published between 1993 and 2014 that used the interviewer-rated Yale-Brown scale. The abstract opens with the WHO ranking OCD "among the 10 most debilitating disorders" and the statement that it "tends to be chronic without adequate treatment."
The effect sizes: "comparisons of CBT with waiting-list (1.31), and placebo conditions (1.33) were very large." Two comparisons that people argue about turned out not to matter: individual against group treatment (0.17) and "exposure and response prevention vs. cognitive therapy (0.07) were small and non-significant."
On medication: "CBT was significantly better than antidepressant medication (0.55), but the combination of CBT and medication was not significantly better than CBT plus placebo (0.25)."
The other direction
The largest effects are against waiting lists and placebo conditions, the easiest comparisons to win. The authors say the trials "have a number of methodological problems" and spend part of the paper on how to fix them. The 0.55 advantage over medication is a moderate effect, not the very large one, and comes from fewer trials. On combination, this analysis and the 54-trial network disagree: here adding medication to CBT did not help significantly; there the authors leaned toward combination in severe OCD. Both are on the record.
What this does not show
It does not say which people do better with a drug added, or that anyone should stop one. It measures the average across trials, and the average includes people who did not respond.
Worth asking
Will you measure my Yale-Brown score as we go, so we know within weeks whether this is working?
Source
Cognitive behavioral treatments of obsessive-compulsive disorder. A systematic review and meta-analysis of studies published 1993-2014 — Öst LG, Havnen A, Hansen B, Kvale G (2015)
Reputable peer-reviewed journal
Read the source: https://doi.org/10.1016/j.cpr.2015.06.003
DOI: 10.1016/j.cpr.2015.06.003
How this was scored
- Study design
- Meta-analysis of randomised trials
- Funding
- Funding not disclosed
- Published in
- Reputable peer-reviewed journal
- Sample size
- not recorded
- Preregistered
- not recorded
- Conflicts disclosed
- not recorded
- Independent of proponent
- not recorded
- Retracted
- No
Read the full scoring rubric, including what it can't tell you.
Published September 29, 2026.
Questions
How strong is the evidence behind this?
veisund rates this source "moderate evidence". Reasonable evidence with real limitations. It scores 63 out of 100 on our published rubric. One caveat travels with that badge: The very large effects are against waiting lists and placebo, the weakest comparators; the authors themselves list methodological problems in the trials. This analysis found no significant gain from adding medication to CBT, which is the opposite lean from the 54-trial network meta-analysis; the disagreement is unresolved. The score is calculated from recorded facts about the source — study design, funding, publication venue, sample size, preregistration — not typed in by an editor.
What is the source for this?
Cognitive behavioral treatments of obsessive-compulsive disorder. A systematic review and meta-analysis of studies published 1993-2014 — Öst LG, Havnen A, Hansen B, Kvale G (2015). Published in: Reputable peer-reviewed journal. DOI: 10.1016/j.cpr.2015.06.003. The full source is linked on this page so you can read it yourself.
Who paid for this research, and does that matter?
Study design: Meta-analysis of randomised trials. Funding: Funding not disclosed. Independence from the proponent is not recorded. Industry sponsorship is one of the most reliably measured biases in medicine, which is why funding carries real weight in the score rather than sitting in a footnote.
Is this medical advice?
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.