New research from a joint UCLA – Harvard Medical Schools study claims that medication studies in the top medical journals are often actually designed in a way that provides misleading – or confusing – results.
The researchers looked at every randomised medical trial over a 2 – year period (June 2008 – Sept 2010) published in 6 of the top medical journals: The Lancet, the British Medical Journal , the New England Journal of Medicine, the Journal of the American Medical Association, the Annals of Internal Medicine, and the Archives of Internal Medicine
The findings, published in the ‘Journal of General Internal Medicine’, looked at all these studies including those that used the three specific, most commonly used types of outcome measures (covering 98% of the studies) – ones which have received increasing criticism from scientific experts.
Surrogate outcomes (37% of studies): these are most likely to be commercially funded by pharmaceutical companies and look at ‘intermediate markers’ and are not thought to be a good indicator of the eventual clinical outcomes they are ‘linked to’. These studies, for example, look at a heart medication’s ability to lower blood pressure, but whilst this is a good measure, it may not be a good indicator of the medication’s impact on the more important clinical outcomes, like heart attacks.
Composite outcomes (34%): these make it difficult to understand the effects of a number of specific outcomes by grouping a number of multiple individual outcomes – “of unequal importance” – together. Critics give the example of grouping outcomes like hospitalisations and mortality — and making conclusions linking the two together.
Disease-specific mortality (27%): like Surrogate Outcome Research, these types of study are again most likely to be commercially funded by pharmaceutical companies and may be misleading as they only look at deaths from one specific cause – rather than looking at these deaths from any cause. Critics point out that this may be misleading because, even if a given treatment reduces one type of death, it could increase the risk of dying from another cause, to an equal or greater extent. Trials that used surrogate outcomes and disease-specific mortality were more likely to be exclusively commercially funded — for instance, by a pharmaceutical company.
Lead author, Dr. Michael Hochman said: “Patients and doctors care less about whether a medication lowers blood pressure than they do about whether it prevents heart attacks and strokes or decreases the risk of premature death. Knowing the effects of a medication on blood pressure does not always tell you what the effect will be on the things that are really important, like heart attacks or strokes. Similarly, patients don’t care if a medication prevents deaths from heart disease if it leads to an equivalent increase in deaths from cancer.”
The researchers undertaking this study went as far as to suggest that “commercial sponsors” may promote the use of outcomes that are most likely to indicate favourable results for their products.
Hochman went on to explain that: “For example, it may be easier to show that a commercial product has a beneficial effect on a surrogate marker like blood pressure than on a hard outcome like heart attacks. In fact, studies in our analysis using surrogate outcomes were more likely to report positive results than those using hard outcomes like heart attacks.”