Stopping Clinical Trials Early: The Downside

April 23rd, 2010 | Sources: BurrillReport, JAMA

Subjects:

Clinical trials are often stopped early when they show a convincing, apparent difference between an experimental intervention and either a placebo or an existing standard of care. The rationale for halting such trials is to let participants who were randomized to the placebo switch to the apparently effective intervention, and to help get the presumably improved therapy to market.

thisonewaseasyHowever, a recent study by Dirk Bassler and colleagues at McMaster University suggests that halting trials early may lead to misleading overstatements concerning the apparent benefits of the intervention.

To reach this conclusion, Bassler’s team compared treatment effects from truncated randomized clinical trials (RCTs) with those observed in trials that addressed the same question but that were not halted early.

The analysis included 91 truncated RCTs and 424 matched, non-truncated RCTs. The results showed that the halted trials had reached exaggerated or misleading conclusions. Remarkably, 62% of the non-truncated RCTs showed no benefit at all for the intervention. Large differences between truncated and non-truncated trials were common when the truncated RCTs had fewer than 500 outcome events.

“Our research shows that in most cases early stopping of clinical trials resulted in misleading estimates of treatment effects,” Victor Montori, a Mayo Clinic endocrinologist and corresponding author of the study told BurrillReport.
 
The authors recommended that scientists truncate clinical trials only near the very end of a study and then only with “a very good reason.” Otherwise patients and physicians will be making treatment choices based on inaccurate information, or worse, opting for a treatment when another one may be more effective.

The study appears in the Journal of the American Medical Association.


 

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