Trial validity decreased by too many exclusions
Otherwise well-designed randomised controlled clinical trials might be of limited use to clinicians if too many patient populations have been excluded. This is the conclusion of research published in JAMA (2007:297:1233–40).
The authors reviewed a random sample of clinical trial papers published
in general medical journals with a high impact factor. They found frequent
exclusions of children, the elderly, women (particularly those lactating,
pregnant or able to become pregnant), patients taking common medicines
and those with diseases other than that under study, which were often
not justified in the context of a particular trial.
Trials among a homogeneous population tend to be smaller, shorter, more
efficient and less expensive than those among a wider population group,
the authors explain. However, they point out that such populations are
generally not representative of those that will ultimately take the medicine
under study. When trial results are inappropriately generalised, future
patients with similar characteristics to those excluded from trials may
be susceptible to unintended harm.
A way forward, they suggest, is for those who design trials to minimise
exclusions and for exclusion criteria to be justified in the text of
trial papers.
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Hospital
Pharmacist