12 Mar 2009

Doping test questioned

A key test for catching drug cheats in sports should be scrapped because it fails to take into account vital ethnic variations, according to a study by a leading Olympic anti-doping lab.

The study, published in the British Journal of Sports Medicine, claims the testosterone test is "not fit for purpose" and should be replaced by an athlete "passport" system that tracks a competitor's biological patterns.

The study, funded by football's world governing body FIFA, was conducted by scientists at the anti-doping laboratory in Lausanne, Switzerland.

Testosterone is a naturally occurring hormone, but is believed to be widely used as a steroid in synthetic form to enhance performance among athletes.

How the study was done
The Swiss researchers examined the testosterone levels of 171 football players in six different countries after steroids were deliberately added to their urine samples. The scientists studied the steroid profiles of 57 Africans, 32 Asians, 50 Caucasians and 32 Hispanics using a chemical analysis.

The researchers reported "significant differences" among the groups. The study found levels were naturally highest among Hispanic players, who on average produced marginally more testosterone than Africans and Caucasians and significantly more than Asians.

"These results demonstrate that a unique and nonspecific threshold to evidence testosterone misuse is not fit for the purpose," the study said.

Under current Wada rules, any ratio of testosterone to epitestosterone greater than 4-to-1 is considered evidence of possible doping. Such a finding leads to further tests to look for synthetic testosterone.

What the study showed
Based on the genetic variations, the Swiss said the testosterone thresholds were actually 5.8-to-1 for Hispanics, 5.7 for Caucasians, 5.6 for Africans and 3.8 for Asians.

The World Anti-Doping Agency, which accredits drug-testing labs around the world, said it was "well aware" of the issue of ethnic variations. It said suspicious T/E results are "just one of several warning signals" and are followed up by carbon-isotope tests that are not affected by genetic factors.

Wada spokesman Frederic Donze also said the agency has been working with the Lausanne lab for more than three years on developing an athlete passport programme.

"This approach ... will allow anti-doping organisations to monitor variations in the athlete's biological profile and subsequently target-test or sanction based on abnormal variations," he said. "This detection strategy is not affected by genetic variations."

High profile cases involving testosterone
There have been a number of high profile cases in sports involving testosterone:

American cyclist Floyd Landis tested positive with a testosterone/epitestosterone ratio of 11:1 at the 2006 Tour de France. He was later stripped of the Tour title and banned from cycling for two years.
New York Yankees star Alex Rodriguez admitted using banned substances from 2001-2003 after Sports Illustrated reported that he tested positive for Primobolan and testosterone during baseball's anonymous survey in 2003.
Two Belarusian hammer throwers were stripped of silver and bronze medals from the Beijing Olympics after testing positive for testosterone.

Plans for a 'passport system'
The ethnic variations, the Swiss study said, make it impossible to apply a universal benchmark for testosterone doping. The scientist instead called for the introduction of a passport system, which measures variations in individual athletes.

"Even if we apply different thresholds we will not be sensitive enough in detection of testosterone and we have to use another system," said Christophe Saudan, a researcher with the Lausanne lab. "Now we have to turn to the biological passport which takes into account the individual range of the athlete.

"The athlete is his own reference. We have to look at the athlete's reference rather than a population reference." The passport system would measure an athlete's baseline blood and urine profiles against numbers gleaned from later tests. Such "longitudinal" tests wouldn't necessarily look for specific substances, but could detect changes in body chemistry that would indicate use.

Jiri Dvorak, FIFA's chief medical officer, said of more than 25 000 doping controls carried out each year from 2004-08 in world football, just 51 tested positive for anabolic steroids.

"In our experience over the past five years we have not found any single one T/E ratio between four and six which has proven to be a positive case," Dvorak said. "We see that there are ethnical differences."

'Findings don't cast doubt on previous tests'
Dvorak, a member of Wada's health, medical and research committee, said he would submit the study to the panel's next meeting in Montreal.

The chairman of the International Olympic Committee's medical commission, Arne Ljungqvist, said the research confirmed what was already known by anti-doping experts and did not cast fresh doubt on previous positive tests.

"Using T/E ratios is fairly accurate and useful as a screening method, but it is never the final proof," Ljungqvist said. – (Sapa, March 2009)