Jan 18, 2012

Misleading Results

Results of medication studies in top medical journals may be misleading to readers

Medication studies in high-impact factor medical journals tend to be misleading -- not only misleading, but misleading by design. That’s the finding of researchers in a UCLA-Harvard study published in the Journal of General Internal Medicine. Researchers analysed randomized trials published in six of the highest-impact general medicine journals over the course of two years (the New England Journal of Medicine, the Journal of the American Medical Association, The Lancet, the Annals of Internal Medicine, the British Medical Journal and the Archives of Internal Medicine), to determine the prevalence of certain types of outcome measures that make data interpretation difficult.

Such as the common surrogate and composite outcomes. These kinds of problems, shaded by bias, have been reported previously and come under recent criticism when judging clinical evidence from the medical literature.

A surrogate end point tends to be a laboratory measure or physical sign that is used in therapeutic trials as a substitute for a clinically meaningful end point that is a direct measure of how a patient feels, functions, or survives. Such surrogates prove useful in well-defined situations, and are expected to predict the effect of the therapy. The appropriateness of their application in clinical trials when it's not certain that surrogate endpoints can be relied upon, continues to be debated.

In the study, surrogate outcomes refer to intermediate markers, such as a heart medication's ability to lower blood pressure, but which may not be a good indicator of the medication's impact on more important clinical outcomes, like heart attacks. Composite outcomes consist of multiple individual outcomes of unequal importance lumped together -- such as hospitalizations and mortality -- making it difficult to understand the effects on each outcome individually.

Sometimes the specific effects of a medication is not a good indication of the eventual clinical outcomes. Lowering blood pressure is less of a concern than prevention of a stroke -- from the patient’s point of view. How a treatment is going to effect the user is often more important to know, than other effects. A point often lost as multiple outcomes of unequal importance are lumped together.

A commercial bias also exists, as 45% of exclusively commercially funded trials used surrogate endpoints while only 29% of trials receiving non-commercial funding did. With a further bias of trials using surrogate endpoints more likely to report positive findings. A positive is easier to show and present favourably. Perhaps the commercial bias to promote the use of outcomes that are most likely to indicate favorable results for their products. However, the possibility that results from such studies are more likely to be positive because they stem from more plausible study hypotheses should not be ruled out.

The way in which study results are presented is critical. The appropriateness of surrogate endpoints and the accuracy of study conclusions based on these outcomes needs further stringent evaluation to determine if positive results from such studies reflect trustworthy findings or provide evidence of inherent systematic bias.

Journal of General Internal Medicine
Volume 26, Number 11, 1246-1252; DOI: 10.1007/s11606-011-1813-7

Written by Dr. Charles Ebikeme for The All Results Journals.

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