NCPA - National Center for Policy Analysis


December 12, 2005

Randomized clinical trials (RCTs) that stop earlier than planned because of apparent benefit to patients often receive great attention and affect clinical practice, but the reasons why investigators decide to stop early are unknown, says the Journal of the American Medical Association (JAMA).

A systematic review up to November 2004 of MEDLINE, EMBASE, Current Contents and full-text journal content database found that 143 RCTs were stopped early and the majority (92) were published in five high-impact medical journals.

According to JAMA:

  • The stopped RCTs are typically industry-funded drug trials in cardiology, cancer and human immunodeficiency virus/AIDS.
  • The proportion of all RCTs published in high-impact journals that were stopped early for benefit increased from 0.5 percent in 1990-1994 to 1.2 percent in 2000-2004.
  • On average, RCTs recruited 63 percent of the planned sample and stopped after a median of 13 months of follow-up, one interim analysis and when a median of 66 patients had experienced the end point driving study termination.
  • Some 135 (94 percent) of the 143 RCTs did not report at least one of the following: the planned sample size, the interim analysis after which the trial was stopped, whether a stopping rule informed the decision or an adjusted analysis accounting for interim monitoring and truncation.

Furthermore, RCTs stopped early for benefit are becoming more common, often fail to adequately report relevant information about the decision to stop early and show implausibly large treatment effects; these findings suggest clinicians should view the results of such trials with skepticism, says JAMA.

Source: Victor M. Montori et al., "Randomized Trials Stopped Early for Benefit," Journal of American Medical Association, vol. 29, no. 17, November 2, 2005.

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