Treatment effects monitoring committees and early stopping in large clinical trials

Treatment effects monitoring is a process carried out over the course of a trial to determine whether it should continue unaltered. The purpose of monitoring is to protect persons enrolled from harm, caused either by exposure to an ineffective or harmful treatment or failure to provide a better treatment. The aim of this paper is to characterize treatment effects monitoring committees (TEMCs) as extant in published trials and to examine the effect of their presence on the premature stopping of a trial.

Trials published in 1990-1995 in the Annals of Internal Medicine, Archives of Internal Medicine, British Medical Journal, Journal of the American Medical Association, Lancet, New England Journal of Medicine or Controlled Clinical Trials were identified via MEDLINE (4279 publications). Abstracts were screened to include only trials with parallel treatment designs and sample sizes of > or = 200, reducing the set to 661 papers. Those papers were then read, reducing the set to 562 after exclusion of papers not reporting trial results. The results that follow come from a review of these 562 published papers and from the responses to two questionnaires. The first was mailed to the corresponding author, and the second to the chair of the monitoring body or other contact as provided by the author in response to the first questionnaire.

Less than half (48%) of the 562 trials had TEMCs. Factors having a positive univariate relationship with the presence of a TEMC include National Institutes of Health (NIH) sponsorship, larger sample size, multicentered, longer data collection and follow-up, and mortality as an outcome. Most of the early stops occurred in trials with TEMCs (66 out of 78). The odds ratios for early stopping for trials with TEMCs versus those without TEMCs was 4.4 (CI: 2.3-8.5).

The evidence suggests that early stopping is associated with the presence of a TEMC, but a substantial number of trial reports do not mention the presence of a TEMC even when one was used to stop a trial early.