The athlete biological passport: an effective tool in the fight against doping.

Athletes dope to trigger physiological changes that provide advantages in competition. Doping leaves a biological fingerprint in the athlete’s body. The Athlete Biological Passport (ABP) is the paradigm in testing that aims to detect this biological fingerprint (1, 2 ). Biomarkers of doping measured or inferred from blood and urine samples are used for that purpose, in the same way that biomarkers of disease are used in medicine as indicators of the presence or severity of a disease. Although both types of biomarkers aim to distinguish a biological fingerprint induced by a specific cause from the usual biological profile expected for a natural physiological condition, biomarkers of doping are collated and evaluated according to standards specific to forensic sciences. Several aspects of the ABP have been developed and validated in recent years. They include strict protocols for the collection, transport, and analysis of samples; a scrupulous chain of custody; an adaptive Bayesian method to evaluate longitudinal biological profiles; and application of forensic standards for the evaluation of doping evidence— with the anonymity of the athlete guaranteed at all steps of the process. The blood passport aims to detect any modification of erythropoiesis, whether by blood transfusion or the use of erythropoiesis-stimulating agents, such as recombinant erythropoietin (rEPO) (1, 3 ). The ABP can be used for intelligence, for sanctioning, for health protection, and, in turn, for deterrence. It can be used for intelligence because antidoping organizations (ADOs) can use data from the passport to define suspicious biological profiles and identify athletes who have them. It can be used for sanctioning because the weight of ABP evidence can be sufficiently high in some cases to prove beyond reasonable doubt that an athlete doped. The ABP can be used for health protection because it provides a direct view of the impact of doping on the athlete’s physiology. Finally, it can be used for deterrence because doping leaves a biological fingerprint, so athletes are no longer able to dope with impunity. In 1996, some sports federations discouraged rEPO doping by introducing upper limits for precompetition hematocrit and hemoglobin measurements. At the time, these analyses were conducted immediately on the field after blood collection, and athletes who tested above these limits were declared unfit for competition. This “no-start rule” was considered a competition rule and not an antidoping rule violation. Each federation had its own internal preanalytical and analytical protocols. The antidoping laboratories conducting these analyses for the federations acquired considerable experience. This experience indicated that most of the preanalytical and analytical conditions set up in hospitals and clinics were not sufficiently exacting to meet the forensic standards required for antidoping analysis. The expertise gained over time by the antidoping community led to the establishment of rigorous protocols. These protocols were submitted over a 2-year period to many experts in the field of laboratory hematology and were officially released by the World Anti-Doping Agency (WADA) in 2009 (4 ). For the protection of athletes, the criteria are conservative, and the acceptance criteria for blood analyses at the laboratory level are extremely selective. For that reason, 5%– 8% of the samples were rejected in the first year the blood passport was implemented, (analytical turnaround time too long, incorrect transport temperature conditions, incomplete documentation, blood samples analyzed only once, and so forth). Currently, many fewer samples are rejected, because all stakeholders have become more experienced, and good couriers have been identified who are capable of delivering refrigerated blood samples collected all over the world within 36 hours. The blood passport was developed with data derived from many clinical trials and has been validated by scientific publications. Standard cross-validation methods were performed to determine the sensitivity and specificity of the adaptive Bayesian model (3, 5, 6 ). In 2006, the most discriminating and stable variables were selected. The need for a network of laboratories 1 Swiss Laboratory for Doping Analyses, University Centre of Legal Medicine, Epalinges, Switzerland; 2 Medical Department, World Anti-Doping Agency, Montreal, Quebec, Canada. * Address correspondence to this author at: Swiss Laboratory for Doping Analyses, University Centre of Legal Medicine, West Switzerland, Chemin des Croisettes 22, 1066 Epalinges, Switzerland. Fax 41-0-21-314-70-95; e-mail [email protected]. Received March 11, 2011; accepted March 16, 2011. Previously published online at DOI: 10.1373/clinchem.2011.162107 3 Nonstandard abbreviations: ABP, Athlete Biological Passport; rEPO, recombinant erythropoietin; ADO, antidoping organization; WADA, World Anti-Doping Agency; ADAMS, Anti-Doping Administrative Management System. Clinical Chemistry 57:6 830–832 (2011) Opinions