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Negative tests; positive for doping: The Athlete Biological Passport Explained

10 Nov 2022

Negative tests; positive for doping

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How does an athlete who has never tested positive for a banned substance get a 4-year ban for Presence or use of a banned substance or method?

In the case of marathon runner Daniel Wanjiru, it was his Athlete Biological Passport, or ABP. The ABP flagged an abnormality in Daniel’s 14th blood sample by comparing it to his previous results over time. The high level of haemoglobin they found wasn’t a positive test – after all, haemoglobin isn’t a prohibited substance. Instead, it was the biological evidence that doping had taken place, and was so convincing that a panel of experts unanimously concluded that blood doping was highly likely to have taken place.

Tracking athlete data over time

So what exactly is the Athlete Biological Passport?

The Athlete Biological Passport is a digital record with an algorithm that records and evaluates an athlete’s test results over time. It has two modules: the steroidal module uses urine samples to monitor the body’s natural steroid production; the haematological module uses blood samples to monitor oxygen transportation in the blood. It’s aim, the World Anti-Doping Agency (WADA) explains, is to “monitor selected biological variables over time that indirectly reveal the effects of doping rather than attempting to detect the doping substance itself”.

When a sample is fed into the ABP, its algorithm evaluates it, comparing it to all the previous results for that athlete, and makes predictions about what the athlete’s biological landscape should look like in the future.

When Daniel first joined the ABP programme, his landscape (known as his ABP profile) was based on norms for his gender, age, ethnicity, and other differentiators. But as more test results were added, the algorithm’s predictions improved and Daniel’s ABP profile became specific and unique to his biology. Not comparing Daniel to another athlete, or to generic ‘norms’, but comparing Daniel to himself.

Daniel’s 13th sample was within normal parameters. His 14th sample showed an unusual increase in haemoglobin concentration, amongst other indicators. His 15th sample was again within normal limits. The ABP detected the spike and flagged the results as abnormal.

Interpretations and sanctions

Though the ABP can make predictions and flag abnormalities with remarkable accuracy, it doesn’t give explanations. Interpreting the evidence is left to humans. At DFSNZ, our Science Manager reviews any abnormal results and then, if justified, they are examined by three independent experts known as the Expert Panel.

They examine the anonymized data and conclude – independently – whether or not the evidence points to doping, or whether there innocent explanations. In Daniel’s case, the experts were unanimous in their belief that the spike in haemoglobin “cannot be explained by any other cause than blood manipulation”. Not a positive test, but definitive biological evidence that doping has occurred. Mr Wanjiru received a 4-year ban for ‘Use of a prohibited substance or method’.

ABP as investigative tool

The ABP’s value isn’t just in its ability to directly detect doping. It’s also a useful tool for investigations, helping to guide decisions around testing.

US cyclo-cross athlete Katie Compton’s out-of-competition urine test in September 2020 came back negative for substances, but her ABP flagged an abnormality. Using information from the ABP, the United States Anti-Doping Agency rescreened the sample using a specialist, substance-specific test known as Carbon Isotope Ratio testing. The result came back positive, and Katie accepted a 4-year ban.

The ABP isn’t just used to sanction athletes. It’s used to make decisions, whether that’s the decision to store a sample, to re-test a certain athlete, or to review a previous result.

ABP sanctions in New Zealand

The Athlete Biological Passport programme in New Zealand has been running since 2014. In that time, most samples we’ve taken have contributed towards an athlete’s Biological Passport. To date, no athlete has been sanctioned directly because of anomalies in their ABPs.

We came close. In a recent case that started similarly to that of Daniel Wanjiru’s, the ABP flagged an abnormal result for a Kiwi athlete with an established history of data in their ABP profile. We investigated, sending the athlete’s anonymised data to three independent experts for their opinion. They unanimously agreed that there was no other explanation for the anomaly but blood doping.

The athlete appealed, presenting a counter argument in the form of a piece of academic research. It was dismissed by two members of the expert panel but brought enough doubt into the mind of the final member that proceedings against the athlete were dropped and the case was closed. To take proceedings against an athlete based on ABP data requires the expert panel to be unanimous in their belief of doping.

We have yet to sanction an athlete as a direct result of data from their Athlete Biological Passport. But, as in the Katie Compton case, we have used ABP data as a tool to guide testing – and it has led to athletes being banned from sport.

We tested an athlete in one of our Olympic sports, and his ABP flagged an anomalous result. Further testing revealed exogenous – or ‘introduced’ – testosterone and the athlete was banned for 2 years.

The future of anti-doping

The ABP is a powerful tool that has been directly responsible for over 180 sanctions since 2009 and we don’t know how many sanctions the ABP is indirectly responsible for. And it’s only going to get better. An Endocrine module is in development, for example, which will detect the abuse of hormones like growth hormone. Another tool in our toolbox. As technology improves, so too will our ability to catch dopers, hold them to account, and protect the integrity and reputation of sport in New Zealand.


'Negative tests; positive for doping: The Athlete Biological Passport explained' | Presented by Hayden Tapper, DFSNZ Intelligence and Investigations Manager, and Ryan Morrow, DFSNZ Science Manager

Content presented live at the 2022 Cambridge Athlete Forum. See also:

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