Hostname: page-component-8448b6f56d-dnltx Total loading time: 0 Render date: 2024-04-16T16:06:31.346Z Has data issue: false hasContentIssue false
  • English
  • Français

Improving traditional intention-to-treat analyses: a new approach

Published online by Cambridge University Press:  23 March 2005

MARCELA HORVITZ-LENNON ,
A. JAMES O'MALLEY ,
RICHARD G. FRANK  and
SHARON-LISE T. NORMAND
MARCELA HORVITZ-LENNON
Affiliation:
Department of Psychiatry, University of Pittsburgh, PA, USA
A. JAMES O'MALLEY
Affiliation:
Department of Health Care Policy, Harvard Medical School, Boston, MA, USA
RICHARD G. FRANK
Affiliation:
Department of Health Care Policy, Harvard Medical School, Boston, MA, USA
SHARON-LISE T. NORMAND
Affiliation:
Department of Health Care Policy, Harvard Medical School, Boston, MA, USA Department of Biostatistics, Harvard School of Public Health, Boston, MA, USA
Get access Rights & Permissions [Opens in a new window]

Abstract

Background. Drop-out, often accompanied by treatment non-compliance, is common in psychiatric trials. Methodologists have criticized the use of a traditional intention-to-treat (ITT) approach in such cases, and have proposed alternative methods. We set out to describe and assess methods for estimation of a treatment effect when the trial is ‘broken’.

Method. We describe a stratified method of moments (SMOM) estimator that assesses treatment effects on subjects who are willing to comply with all the treatments under study. A simulation study and a re-analysis of data from an antipsychotics trial are used to compare SMOM to ITT, as-treated, and adequate estimators.

Results. The new estimator retains good statistical properties under different levels of non-compliance and drop-out mechanisms. The re-analysis indicates that SMOM yields more precise results.

Conclusions. Although the traditional ITT approach provides a valid method to estimate treatment effects, it can be biased in the presence of treatment non-compliance and drop-out. It is critical that researchers move beyond traditional approaches when trials are broken. A key first step is to consider non-compliance and drop-out as two independent phenomena, tracking and reporting rates separately.

Type
Research Article
Information
Psychological Medicine , Volume 35 , Issue 7 , July 2005 , pp. 961 - 970
Copyright
2005 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

Presented in part at the 15th International Conference on Mental Health Services Research organized by the National Institute of Mental Health, Washington, DC, USA, 2 April 2002. This work was completed while Dr Horvitz-Lennon was Instructor, Department of Psychiatry, The Cambridge Hospital, Cambridge, MA, and Harvard Medical School, Boston, MA, USA.