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Ward et al. compared psychological therapies and usual general
practice care for patients with depression. They concluded psychological
therapy was more effective than general practitioner care at 4 months, but
at one year there was no difference in outcome (1).
The authors’ power calculation indicated that each group needed 65
people to detect a mean difference in outcome at 90% power and 5% level of
significance. Six out of 7 groups had less than 65 people at both 4 months
and 12 months. The lack of difference at 12 months may reflect a type II
error, failing to reject the false null hypothesis. This could also
explain why they detected no difference between the two psychotherapies.
The use of antidepressants in all the groups creates several
difficulties. We don’t know when the study medication was started or
whether the average time differed between the groups. If there was a delay
in starting antidepressant treatment then the 4 month assessment may not
have detected its full benefit. This is likely to have had a larger effect
on the GP group where antidepressants were more frequently prescribed.
These points add a note of caution to the authors’ conclusions.
Finally 80 of 113 psychotherapy treatments had finished by four
months, whereas general practitioner care continued throughout the 12.
Would prolonged psychotherapy have demonstrated more effective results?
Department of Public Health and Epidemiology, University of Newcastle,
Medical School, Newcastle upon Tyne NE2 4HA, UK.
1 Ward E, King M, Lloyd M, et al. Randomised controlled trial of
none-directive counselling, cognitive-behaviour therapy, and usual general
practitioner care for patients with depression. I: Clinical effectiveness.
BMJ 2000; 321 :1383-8.
No competing interests
04 January 2001
Stage 3 Medical Student
Newcastle Medical School, Department of Epidemiology and Public Health