Evaluation and Improvement of the Implementation of the Intention to Treat Model in Controlled Trials of Psychotherapies

Funded Activity Summary

Randomized controlled trials (RCTs) are the best way to determine whether patients benefit from a new treatment. In these trials patients are randomly assigned to the new, active treatment, or to a placebo or existing treatment. The groups are compared at the end of the trial. RCTs may be mounted for psychotherapy and educational programs as well as for new drugs and other medical procedures. A major problem for RCTs concerns their statistical analysis when some participants drop out before the end of the trial. Dropout is common in trials. Participants may drop out because they feel no benefit from the treatment, dislike side effects, or even because they have recovered quickly. Thus, to compare the groups remaining at the end of trial may introduce serious bias. The Intention to Treat (ITT) principle which has been widely adopted states that outcomes from all patients who enter a trial should be compared at its end. To achieve this, the last available observation for a participant who withdraws is often 'carried forward' to the end of the trial. While currently believed to be conservative, there is evidence that this approach is not always optimal. This project will examine the way in which dropout is treated in trials of two common psychiatric conditions: depression and anxiety disorders. The project will also undertake simulation research to investigate which of a number of modern methods of data analysis yield the most accurate results when participants drop out, and how changes in the design of trials might improve accuracy. The project is important because it will enable researchers to improve the conduct of trials in the future. Erroneous conclusions drawn from RCTs stand to condemn those suffering from disorders to ineffective treatment and to lead to the premature abandonment of potentially useful interventions which are falsely claimed to lack efficacy.

Funded Activity Details

Start Date: 01-01-2005

End Date: 01-01-2007

Funding Scheme: NHMRC Project Grants

Funding Amount: $409,000.00

Funder: National Health and Medical Research Council

Research Topics

ANZSRC Field of Research (FoR)

Psychiatry (incl. Psychotherapy)

ANZSRC Socio-Economic Objective (SEO)

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Other Keywords

anxiety | biostatistical methods | controlled clinical trial | depression | individual psychotherapy | intention to treat | psychotherapy

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