Peter Bol tests positive for EPO

All the Aussies on twitter on Facebook supporting him. Embarrassing really.

No I think you’re misinterpreting him. He is saying the A sample has been tested twice by two independent sources and the B sample is yet to be tested in any capacity. If the study is believed to be representative, then there is still a reasonably high chance (50%) the B sample comes back negative. Or it comes back positive. We don’t know anything but the A sample was positive and confirmed positive.

All correct, apologies for being misinformed on the B sample situation. After reading the study again I think we can have a reasonable hypothesis that the overwhelming probability is that Bol’s B sample will confirm his A sample. Barring human error (on either sample) or a major stroke of fortune for him the multiple analyses/eyes on his first sample are unlikely to be overturned.

So is the A sample tested twice before a finding on A is issued, or just once, with the result verified? This is key. Is the B sample from the same collection as the A, or is it a uniquely collected sample? These details are critical for knowing where Bol stands now.

Which is complete nonsense of course.

Again, I’m just trying to understand. Verification of the A result can mean you took another aliquot of the sample and repeated the assay and the same result was obtained OR it can mean that another expert or experts looked at the results of the initial assay and verified they agree with the interpretation. If it’s the former, Bol is guilty. If it’s the latter, then we don’t know yet.

You’re not one of those people who believe all predictions are really 50/50 because they either happen or they don’t.

I don’t know the rate of false positives for this test because we don’t know how the detection window is adjusted. But do you really think WADA would rely on a test that is a crapshoot like this?

I would assume they repeat the assay, but I’m not 100% sure on that. But that doesn’t conclusively mean he is guilty. Again - that’s the point of the B sample. The study followed WADA protocols - so their urine would have been separated into separate aliquots as well I believe (haven’t had time to read the methods fully).

Both A and B samples come from the same original sample. In the case of urine, you collect one sample and then split it into two separate containers. The A sample is tested immediately, the B sample is frozen and can be used to confirm a positive finding (as in this case) or to test retrospectively (they can be kept for 10 years).

This document was helpful to me:

usada.org

What happens to My Sample?

Guy Infront

Learn more about what happens to an anti-doping drug test sample (urine or blood) once it has been collected from an athlete.

Open link

It seems if I’m reading it right, they will have done all the tests prescribed in the study to follow up and then had 2 other scientists review their findings. Again, I feel like his best hope is human error with mishandling of his sample. Timing is paramount for the EPO findings and the samples are of identical timing so they should show the same things.

For his sake, I hope it’s the latter.

I doubt B sample will be negative.

Oh I don’t disagree with you. I was simply trying to clarify what others had said. By no means am I asserting that in reality there is a 50/50 chance a positive A sample for synthetic epo actually means there’s only a 50% chance there was foul play. I was simply restating what others had said and what the paper implied as there seemed to be some confusion.

Yep, thanks.

Once again, thank you for sharing. No, it does not seem like the A sample is retested, just that the results are verified by two experts. This definitely needs to be clarified. This is a BIG difference. In the study you presented to all of us, it was only when the assay was repeated on the second sample that the performance of the test allowed for a highly accurate delineation of the true positives versus the false positives. Simply have some experts look at assay #1 and confirming they agree with the interpretation of the results is not the same as rerunning the test. It would be nice if somebody who REALLY knows what’s done to an A sample would chime in. If in Bol’s case, the 2nd time the synthetic epo assay will be run has yet to happen (awaiting testing of the B sample), then we remain in a period of uncertainty. If the assay was repeated twice on the A sample and a positive A result means that both times a tested aliquot from A came back positive, then the chance the B sample will be negative is close to zero. Honestly, I’m amazed nobody posting here knows for sure how it’s done.

OMG, go to google and look up the concepts of sensitivity, specificity, positive and negative predictive value as they apply to any diagnostic test. I know this is dry stuff, but it’s critical if you really are interested in whether a person has a true positive test result or not.

Maybe I’m reading it wrong but I was picking up in the study that part of the issue was performing all of the different tests on the sample. By different tests I mean they had multiple ways to detect an AAF. Three were mentioned in the study. If you do just one it is insufficient, but if you do all 3 you rule out the false positives. Again could be reading it wrong.

To my point look at the USADA document and it says that if a positive result is returned they do “robust and targeted confirmation procedures.” That feels to me like what was done in the study and while done by the same scientist would be sufficient to rule out most false positives.

I think you are correct in your interpretation of their language and I take back my assessment. My apologies. I think they run the assay twice on the A sample if the first run is +, and only report a positive A out if both runs are concordat and positive. If so, Bol’s B sample will be positive nearly 100% of the time based on the performance characteristics of the test.

You have to worry now about the association with his cousin, Femke Bol