Passport to clean competitionBMJ 2012; 344 doi: https://doi.org/10.1136/bmj.e2077 (Published 22 May 2012) Cite this as: BMJ 2012;344:e2077
- Kirsten Patrick, editorials editor, BMJ,
As the stakes for top level competitive athletes become increasingly high, so does the pressure to perform better. The use of banned substances is widespread. But catching doping cheats is difficult, as highlighted by the drawn out case that resulted in the recent suspension of Alberto Contador from professional road cycling for two years. Contador tested positive for clenbuterol in a blood sample taken on 21 July 2010, but it was not until February 2012 that the Court of Arbitration for Sport ruled on the matter after much legal wrangling.1 In the intervening time Contador won the 2010 Tour de France and the 2011Giro d’Italia.
Traditionally, doping tests have focused on detecting banned substances in blood or urine samples provided either at the time of competition or at random time points outside competition (as introduced by the International Olympic Committee in 1994). The drawbacks of direct testing are many. Athletes may dodge tests, for example, and many substances have a short window in which their metabolites are excreted and detectable. Some substances that are banned in competition, such as corticosteroids, may be used to treat an injured athlete, which, as the World Anti-Doping Agency (WADA) acknowledges, can hardly be branded as cheating. It has developed guidance that requires athletes to declare the therapeutic use of banned substances.2 It’s also not uncommon for athletes to claim that they have tested positive for a substance because they have eaten contaminated food.
Another problem that grew towards the end of the last century is “blood doping”—that is the infusion of homologous or autologous red blood cells before a competition or, more recently, the use of recombinant human erythropoietin, which stimulates endogenous red blood cell production. Blood doping enhances performance by improving an athlete’s oxygen carrying capacity, which is particularly desirable in endurance sports. It was made illegal only in 1986—the US cycling team at the 1984 Olympic Games used blood transfusions. Use of blood transfusions is difficult to prove because it is hard to establish that high red cell and packed cell volumes are due to blood doping, although tests are now being developed that can tell whether red blood cells have been stored. Recombinant erythropoietin can be detected by a reliable urine test that has been in use for nearly 10 years, but poor timing of a test can still miss a user and, just as in the recreational drug market, new synthetic agents that may not be detected by current tests are constantly being developed.
How can sporting authorities hope to stay ahead of the increasingly sophisticated doping game? For some banned substances a shift away from direct detection to indirect detection through longitudinal monitoring of biomarkers seems to be an appealing answer. A practical application of the athlete’s “blood passport” was first developed in 2005, and WADA finalised its operating guidelines for biological passports in December 2009.
The International Cycling Union (UCI) was the first organisation to adopt biological passports. According to UCI’s medical adviser, Mario Zorzoli, the organisation made it compulsory for professional road cyclists to participate in its biological passport programme in 2010. The programme is used both for profiling athletes and as a basis for sanctioning them. Previously a few cyclists had been disqualified or suspended from competition because their reticulocyte count during a competition was much higher than in training periods. The biological passport formalises this approach. The top cyclists in other disciplines, such as track and off-road cycling, are also now subject to regular sample collection both in and out of competition, although not necessarily as part of a biological passport
To date some 19 national and international sporting organisations have implemented some or all aspects of the athlete passport. Recently, Hélder Ornelas, a long distance athlete from Portugal, became the first runner to be found guilty of a doping violation solely on the basis of the biological passport (that is, without any positive test results). The Portuguese Athletic Federation declared him ineligible for competition for four years after analysis of blood samples collected between December 2009 and November 2010 as part of the International Association of Athletics Federations’ (IAAF) biological passport programme suggested use of banned drugs or blood doping. IAAF president, Lamine Diack, said: “Those who try to cheat within the athletics community should be warned that the athlete biological passport is not merely a concept but rather an efficient method that is now being used by the IAAF anti-doping department to identify, target, and catch those who believe that doping is the ... route to success.”
How does the biological passport work?
The athlete’s passport builds on WADA’s existing strategies to test elite athletes for banned substances. Top level competing athletes who are affiliated with a sporting organisation that subscribes to WADA’s anti-doping requirements must give information on their whereabouts for every day of the year so that they can supply a sample for testing when required. For the biological passport athletes are tested without notice both in and out of competition, with roughly 15-20 tests over two years. Changes in biological and non-biological markers are tracked over time through statistical modelling using the athlete as his or her own reference. This system allows authorities to consider whether competition values fall reasonably within a range that could be expected for that individual based on observed intra-individual variability over time and natural variability for the marker within a population reference group⇓ ⇓. For the haematological measurements (box) only haemoglobin and the OFF-hr score, which takes into account the relation between haemoglobin and reticulocyte concentration, are used in the bayesian model that is used to define a possible anti-doping rule violation. Since reticulocytes tend to decrease when haemoglobin is artificially high, the combination of high haemoglobin and low reticulocytes gives a high OFF score.
Haemotological tests in the biological passport3
Red blood cells
Packed cell volume
Mean corpuscular haemoglobin
Mean corpuscular haemoglobin content
Mean corpuscular volume
Absolute number of reticulocytes
% of reticulocytes
OFF-hr score (haemoglobin− 60√% reticulocytes)
So far at least eight cyclists have been suspended on the basis of data from their biological passport. In some cases the biological passport has led to targeted out-of-competition testing for erythropoietin, which was subsequently detected.
Of course, as with any positive test result, the athlete is given the opportunity to explain the abnormal findings (for example, by claiming a normal physiological condition, medical condition, or treatment of a medical condition) and may contest the allegation of doping. However, in the past when the only scientific tool available to anti-doping organisations was direct testing, athletes suspected of blood doping often had their homes searched for blood products, transfusion equipment, and drugs, and the biological passport may obviate the need for such invasion of privacy.
Furthermore, according to Zorzoli, the introduction of the biological passport has had a measurable deterrent effect on doping. Together with his colleague, Francesca Rossi, he examined 10 years of data from cyclists’ tests and found that the proportion of extreme values pattern of reticulocyte percentage—one of the most reliable markers of blood doping—has fallen dramatically, with almost none detected since 2009, the year after the passport was introduced.4
Although an athlete’s biological profile is kept confidential— only a few people from regulatory authorities and the athlete have access to the password protected data— some athletes have published data from their biological passports to encourage clean competition. In 2009 the British cyclist Bradley Wiggins began publishing his haemoglobin and OFF score results online before and during the Tour de France.
Of course, athletes who practise blood doping need doctors to help them to do it, as highlighted by the case of Eufemiano Fuentes, the controversial Spanish gynaecologist and sports physiologist. Fuentes was arrested after a series of police raids across five Spanish provinces in 2010, in which blood products, equipment, hormones, anabolic steroids, and erythropoietin were seized.5 He is alleged to have worked with a number of high profile road cyclists, including the recently suspended German cyclist, Jan Ullrich, as well as with footballers and track athletes. Fuentes denies having performed illegal operations. Athlete passports are also likely to discourage doctors from aiding doping.
So does this mean that the days of cross sectional testing for banned substances may be over? The main limitation of the biological passport is that it is very costly—administering the passport for professional road cyclists alone costs several million euros a year. Much of this is met by the cycling teams (about €120 000 (£96 000; $153 000) for a team of 25 cyclists a year), although UCI contributes and the major competition organisers also pay an annual fee. Zorzoli says that although the laboratory analysis of samples is quite cheap, frequent collection of out-of-competition samples by trained individuals all over the world and transport of samples to the laboratory within 36 hours in refrigerated conditions, as set out by WADA, is expensive. In addition, not all banned substances are currently covered by the biological passport, though it is likely to be expanded in the future. WADA is, for example, currently developing the capacity to include an endocrine module that will allow steroid profiling—an “individual hormonal blueprint.”
In future it may be possible to track a wide range of variables for a single athlete over time, and the importance of the biological passport in detecting cheats may supersede that of traditional doping tests. Although it is not currently feasible that every athlete competing in the 2012 Olympic Games should be required to have an athlete’s passport, the International Olympic Committee may require it for future games.
Cite this as: BMJ 2012;344:e2077
Competing interests: The author has completed the ICMJE unified disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declares no support from any organisation for the submitted work; no financial relationships with any organisation that might have an interest in the submitted work in the previous three years; and no other relationships or activities that could appear to have influenced the submitted work.
Provenance and peer review: Commissioned; not externally peer reviewed.