Are clinical trials inadequate to ensure new treatments are safe?
Expert suggests a more gradual introduction to patients
Concerns over whether the tests a treatment undergoes before general release are enough to ensure its long-term safety have been raised in an editorial by Dr Vijay Sharma, Clinical Editor of BMJ Clinical Evidence. He suggests that treatments should be introduced gradually so that evidence can be built up and the treatment can find its proper niche.
To illustrate this, Dr Sharma discusses the recent debate on the long-term safety of drug-eluting stents used to unblock arteries and slowly release drugs to stop blood clots blocking the stented arteries. Following introduction in 2002, these were used enthusiastically. However, from 2006 several reports highlighted an increased risk of clotting as much as one year after treatment (late-stent thrombosis).
Dr Sharma questions why this risk was not detected sooner. One reason may relate to the outcomes that early clinical trials set out to measure. Another may be that trials have predominantly focused on low risk cases, yet drug-eluting stents were also used in complex cases, where the underlying risk of clotting is higher. More complex cases also require the use of more stents and longer stents, further increasing the risk of late-stent thrombosis, he explains, pointing out that all adverse effects must be carefully assessed in large-scale studies. However, they must also be balanced against the threat posed by coronary artery disease itself, and interpreted in the context of other treatment options.
In his editorial, Dr Sharma concludes: ‘Treatments are often greeted with enthusiasm when they first appear only to fall into disfavour when adverse effects are found. Then, with time, some of these treatments return with a more limited and clearly defined use. To avoid this pattern, adverse effects should be actively sought, and treatments should be introduced gradually so that experience and evidence can be built up and the treatment can find its proper niche.’
01.07.2009
