92% of statistics are taken out of context…

A better response to the “92%…” argument has been written by Robin Lovell-Badge and can be found on our website here.

I thought I’d dedicate an entire post to a certain statistic which has been repeatedly misused and misunderstood by animal rights groups.

92% of drugs that test successfully in animals fail during human trials

You will find animal rights organizations, such as PETA and PCRM, all using this statistic. Often claiming that this shows that “animal research doesn’t work”.

The statistic is from the FDA (Food and Drug Administration), used to illustrate inefficiencies in drug development. However the actual statistic is much broader, it should be:

92% of drugs fail during human trials

The original quote was:

A new medicinal compound entering Phase 1 testing, often representing the culmination of upwards of a decade of preclinical screening and evaluation, is estimated to have only an 8 percent chance of reaching the market

Now it is true that they have passed animal testing to get to human (clinical) trials, but it also means that they have passed non-animal pre-clinical tests, such as in vitro. Consider:

92% of drugs that have successfully passed in vitro tests, fail during human trials

Misleading? Yes. So the next obvious question:

Why do drugs fail at the clinical stage?

Drugs fail clinical trials for two reasons – they don’t work well (lacking efficacy) or they are potentially dangerous. Drugs may fail at different stages of clinical trials – so sometimes a relatively rare, but potentially dangerous side effect turns up late into human trials when many thousands of humans are being used (late in clinical stages many more humans than other animals may have tested the drug – as more people/animals are tested, more side effects are discovered); equally some drugs may simply be ineffective in humans, or ineffective in enough humans (no one wants to release a drug that only works in, say, 30% of people – unless that 30% is a particular and selectable demographic e.g. children), this is bound to be the case since animals are not perfect models for humans, just as humans are not perfect models for other humans (thus why some people get adverse drug reactions and not others).

According to the FDA report, which suggests various improvements to the drug development process, the top area where improvements could be made is to improve the animal models (not remove, but use and improve – they also accept the good track record of animals for finding dangerous chemicals in toxicology tests), with the increase in genetically modified animals allowing us to create better animal models, hopefully we will see that 92% statistic drop.

It is worth highlighting that the FDA says many drugs are failing clinical trials at late stages, meaning that problems with drugs are not becoming clear until they are tested in many people – so it is a mystery as to why the animal rights groups try and put the blame solely on the shoulders of animal research.

What about the benefits of animal safety tests?

Well why DO we use animal safety tests? The 92% statistic ignores all the benefits of safety tests, so:
You have 1000 drugs entering animal safety tests
900 of them fail, of which, say, 20 might actually be safe in humans (false positive).
Of the remaining 100, 92 fail human tests

[The above stats are made up for illustration purposes. Approx 90% of drugs fail at the animal testing stage, and false positives aren’t (cannot legally or safely be) measured]

Therefore:

90.5% of dangerous drugs have been kept out of clinical trials thanks to animal safety tests**

(However 92%of drugs have still failed clinical trials)

**[[Dangerous Drugs removed by animal safety tests]] / [[Total number of dangerous drugs]] = [[880/972]]

We can see that the lower statistic makes no mention of the benefits of animal safety tests made clear by the top statistic.

It is worth noting that around 90% of drugs are removed at every stage of safety tests, i.e. 90% are removed at non-animal pre-clinical safety tests, 90% at animal stages, and 90% during human clinical trials.

Check back on the website for more AR debunking!

Cheers

Tom

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