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Wada stands by Salbutamol test

Man responsible for test says he made ‘a terrible blunder’ when calculating the threshold

The World Anti-Doping Agency (Wada) has defended its Salbutamol test after it accepted Chris Froome had not committed an anti-doping rule violation despite returning a sample with high levels of the asthma drug during last year's Vuelta a Espana.

Attempting to explain how he was cleared, Froome said that it was possible to take the same amount of Salbutamol every day and yet have very different readings.

“There doesn’t seem to be a reliable correlation between what you inhale and what you excrete. We also know that a reading can be significantly affected by dehydration.”

Froome drew people’s attention to recent comments made by Ken Fitch, the man responsible for Wada’s Salbutamol test, who says he made a ‘terrible blunder’ when calculating the threshold for an abnormal finding and who has been pressing Wada to change its rules for several years.

According to Froome: “There are issues that do need to be looked at urgently – and I am sure they will be – as nobody wants other clean athletes to be faced with a similar situation.

“I would welcome the publication by Wada of the scientific studies they relied on both to create the current testing regime and to exonerate me. I am sure these will help everyone understand the complexities of the case and the risk of false positives for all athletes who suffer from asthma and use Salbutamol to manage their symptoms.”

However, in a statement on Tuesday night, Wada said: "Each case is assessed on its own merits and this decision changes nothing about the test or the regime.

"At present, there is no evidence that a change to the threshold or decision limit for salbutamol is required. Wada has noted some public comments questioning the salbutamol threshold and how it was determined.

"It should be pointed out that studies conducted over the past 10 years – both Wada-funded and independent – have reinforced the legitimacy of the current threshold.

“However, mindful of the complexity of some specific salbutamol cases, in particular the fact that different routes of administration cannot be distinguished by urine analysis, Wada will continue to consult experts in the field and carry out research in this area. As with every aspect of the Prohibited List, as fresh scientific data is made available, Wada assesses it in order to ensure the latest research is being applied and that all athletes’ rights are best protected.”

Wada points out that there is a very good reason why breaching its threshold does not constitute a failed test, but is instead merely a trigger for further investigation.

“Unlike most substances, given the variables that exist with salbutamol depending on conditions specific to each case, the rule is designed to afford athletes found to have exceeded the threshold with the opportunity to prove how it has occurred and justify proper therapeutic use.”

It said that after considering Froome’s case, “… it became clear to Wada that, in particular, the combination of his within-subject variability for salbutamol excretion, the sudden and significant increase in salbutamol dosage prior to the doping control, and the number of consecutive doping controls meant that the analytical result could not be considered inconsistent with the ingestion of a permissible dose of inhaled salbutamol.”

Alex has written for more cricket publications than the rest of the team combined. Despite the apparent evidence of this picture, he doesn't especially like cake.

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The Gavalier | 5 years ago

Anyone else just completely bored with this now?

slappop replied to The Gavalier | 4 years ago
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The Gavalier wrote:

Anyone else just completely bored with this now?

Well, people are still talking about it a year later. I'm sure it'll be anything but boring for the next cyclist caught up in this.

"I'll admit I made a terrible blunder" - Ken Fitch

Drinfinity | 5 years ago

This looks like a textbook case of the statistical pitfalls of a screening programme. A correlation is created based on a small population. An alert limit is then set, based on the mean and sd of that population’s variation. Now we apply it to a completely different individual, but expect the same alert limit to be valid.

This approach might be appropriate if it is reasonable to expect the subject is drawn from the same population as the original data, there aren’t enough observations on the subject to draw a control chart, the consequence of type I error (false positive) is low, and there is an effective (if more expensive) follow up. In the case of grand tour cyclists, we should not expect the variation to be the same as swimmers, and none of the other assumptions hold. Presumably Sky used a competent statistician who pointed out the very different  sd given the extensive data they have, showed where the alert limits should be drawn, and WADA be like “fair enough”.

Anyway, I’m a stats nerd, and this case shows why stats is really important.

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