Effectiveness of drugs 'overstated because of biased testing'

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Effectiveness of drugs 'overstated because of biased testing'

 

By Steve Connor, Science Editor

Published: 15 September 2007

http://news.independent.co.uk/sci_tech/article2964464.ece

 

 

Pharmaceutical companies are overstating the effectiveness of their drugs,

and may be placing patients at greater risk, because animal laboratory

studies they fund are biased, it was claimed yesterday.

 

A survey of nearly 300 animal-test studies involving six different

experimental drugs suggested that such flawed methodology is rampant in

the drug-testing industry.

 

About two-thirds of the studies, which were all aimed at testing drugs

with the potential to treat stroke patients, did not use a proper

" randomised blind " methodology, the British Association's Science Festival

in York was told.

 

A similar proportion did not conform to the standard methodology where the

experimenters were deliberately left " blind " as to which animals have been

given the drug until the end of the experiment. " We show that animal

experiments modelling human stroke often overstate how good drugs are at

treating stroke, " said Malcolm Macleod, a consultant neurologist at

Stirling Royal Infirmary, who led the stroke study.

 

" This goes some way to explaining why stroke drugs tested in animals do

not appear to work nearly so well in humans.

 

" It is certainly the case that human health in clinical trials would be

better served with higher quality animal data, " he added.

 

Dr Macleod said that most research using animals to test the effectiveness

of drugs suffers from poor-quality controls which lead to subjective

assessments and result in an inherent bias that makes the drug seem more

powerful than it really is.

 

" It is highly likely that these flaws are also present in other fields of

science. As scientists we need to improve how we conduct experiments using

animals if we are to retain the confidence of the public, " he said.

 

Animal studies looking at the effectiveness of a stroke drug called

NXY-059, made by AstraZeneca, found that it improved outcome by more than

50 per cent.

 

However, when animal studies involving the drug were properly randomised

and blinded, they showed that the improvement was actually between 25 and

30 per cent.

 

" We have reported similar findings for other interventions, but what is

disturbing about the data for NXY-059 is that – for a drug where most of

the published work was funded by the drug manufacturers – the impact of

poor study quality was much more pronounced, " Dr Macleod said.

 

" Another concern with the data for NXY-059 is that the number of animals

used... was generally too small to allow a precise estimate of outcome, "

he added.

 

Professor Michael Bracken, an epidemiologist at Yale University, said that

the serious flaws and inadequacies in animal research raised questions

about the way animal studies are evaluated for their relevance to

medicine. " This lack of advanced scientific methods leaves many questions

about the value of animal research unanswered, and exposes patients and

research volunteers to clinical trials that could be based on flawed

animal studies, " Professor Bracken said.

 

" The general public takes the view that it will only tolerate animal

experiments if the results improve human health, but how much animal

experiments improve human health is a scientific question. The key

question is whether animal studies translate to human medicine. " .

 

Derek Fry, a Home Office inspector of animal experiments, said that the

authorities are concerned about the conduct of many studies looking at the

effectiveness of drugs. " Scientists are expected to be objective but they

are only just realising how subjective they can be, " Dr Fry said. " When you

look at the published papers, it's often quite difficult to see whether

they are randomised, " he said.

 

" However, this only applies for a very limited subject. Most animal trials

involving drugs are done for safety reasons,rather than efficacy. "

 

Animal experimenting

 

* The number of experimental procedures on animals increased by 4 per cent

last year to just over 3 million

 

* 83 per cent of experiments involved mice, rats and other rodents. Fish

accounted for 9 per cent and birds 4 per cent.

 

* Dogs, cats, horses and monkeys – which are given special legal status –

were involved in less than 0.5 per cent of experiments

 

* In 2005, 957,500 procedures – one in three of the total – involved

genetically modified animals. This compared with just 8 per cent in 1995

 

* Rodents accounted for 98 per cent of the genetically modified animals

that were used for experiments

 

 

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