Peter Bol's doping suspension lifted - B sample comes back "atypical"

Sorry, I’ve been off the thread. I’m not an expert regarding the details of the epo assay. All I can say is that every diagnostic test, even when done properly, has a rate of false positives and negatives and so a corresponding sensitivity and specificity. Often as a test is more sensitive, more likely to find a doper, it is less specific, there for less likely to be negative in non dopers, and vice versa. No diagnostic test is 100% accurate, or few anyway. Knowing these performance characteristics is critical for interpreting the results. In the report I reference, the currently used epo assay is wanting in both regards, missing dopers and falsely identifying as positive non dopers. This latter problem was greatly remedied in the study by running the B sample and only labeling a person as positive if positive twice. If you go to the old thread, the study is posted there.

Now we have an atypical finding…the plot thickens in the sense that it seems likely someone screwed up somewhere along the line.

Yeah, ok, definitely above my pay grade….Honestly, it really should not be so opaque. Any assay has established outcomes, and published performance characteristics. It should be straightforward for the testing agency to explain the results and their interpretation in this and any other case.

What is an "atypical finding"?

But sorry Australian anti-dopers, he has to be positive on both tests to be convicted.

Given that investigation is ongoing,

Atypical Finding: A report from a WADA-accredited laboratory or other WADA-approved
laboratory that requires further investigation prior to the determination of an Adverse Analytical
Finding, as provided in the International Standard for Laboratories or related Technical
Documents.

Mine, too. Layman’s guess: first pass at this, they saw one band that looked funny and made the judgment call that it was an AAF. Second pass, they did further testing that was even more borderline, but his series of EPO bands/patterns remain unusual. Either way, this is why we should have the ABP and they can make an informed judgment if they’re seeing something truly unusual or he’s just an atypical guy

The honorable Thomas Bayes strikes again!

No doubt EPO is hard to test, so they look at the possibility from all angles.

While I may complain EPO test is problematic given inconsistencies, i am sure WADA and others are trying their best.

Huh, so who are the Australian's you're having a shot at.

But thanks for stating the obvious re the "both tests" bit.

y'all have done how much reporting on doping and anti-doping and you still don't know what an atypical finding is? you for real?

i swear rojo logs in under wejo's name sometimes

The wire transfer finally cleared into the lab's Swiss bank account.

By that logic, he got unlucky with the A test.

"The investigation into the matter remains ongoing. Sport Integrity Australia will, as part of its investigation, proceed to consider whether any anti-doping rule violations have been committed,” the government-backed agency said in a statement".

What, are they out to get him or something? He was cleared, get over it. What else can they charge him for? No whereabouts violations.

Whoever leaked the A sample results should be worried about a defamation case.

Unless there was some other data linked at a later stage, the data presented in the other thread showed the specificity of the A sample was 100%

That is zero false positives.

The positive predictive value is therefore 1 or 100%.

In other words, based on the data, you can assume an athlete is a doper based on the A sample.

If this were a medical diagnostic test you would have certainly diagnosed the disease based on the A sample alone.

In fact from a medical perspective, presented with both the positive A and negative B, (based on the performance of the test according to the data), it would still confirm a positive diagnosis.

The B sample wasn't "negative". It was "atypical".

No such thing as a perfectly specific or perfectly sensitive test in the real world.

ncbi.nlm.nih.gov

Sensitivity and specificity of detection methods for erythropoietin doping in cyclists

Recombinant human erythropoietin (rHuEPO) is used as doping a substance. Anti‐doping efforts include urine and blood testing and monitoring the athlete biological passport (ABP). As data on the performance of these methods ar...

Open link

Here is the study again. In this study, the first time a sample is tested, there are false positives and at that point the PPV is only 50%. When the same sample is retested, the false positive rate falls to zero if you require both runs of the assay to be positive to call it an adverse analytical finding. In real life testing, is the A sample screened once, and if positive, tested again and found to be confirmed positive before issuing the A positive result? If yes, then you are correct.

So the A sample was tested twice and was positive each time?

This is actually the system working. False positives are alway a possibility which is why they have a B sample to confirm. It's crappy that someone leaked the A sample result early on but the testing is functioning as intended

But, this isn't the end of the line. He is still being investigated because of the A sample result, all that's happened now is that his provisional ban has been lifted. He'll likely be exonerated but it's right that they continue to investigate, some of the biggest doping busts (like Armstrong) are a result of investigation rather than testing