Nature has a correspondence in this week's issue on my recent piece on the poor state of data on doping. Simon Evans of Uppsala University argues that drug testing, as currently employed by anti-doping agencies, cannot be used to evaluate the prevalence of doping. He writes:
Roger Pielke Jr suggests that doping prevalence can be estimated by drug testing of athletes (Nature 517, 529; 2015). I contend that this method is flawed: as the autobiographies of some athletes attest, regular dopers have a track record of avoiding testing positive.These procedures are (a) statistical and (b) based on surveys of elite athletes. He cites the results on Hon et al. (recently discussed here), which indicate that 14% to 39% of elite athletes dope.
To estimate doping's true prevalence, two procedures that circumvent inherent weaknesses in simple counts of positive test results are useful.
I don't disagree with anything Evans writes, and find his argument reasonable. However, if it really is the case that drug testing cannot be used to detect doping then it is also the case that the results of drug testing cannot be used to evaluate the effectiveness (or not) of anti-doping regulations and agencies.
Taken to the limit, this would mean that anti-doping regulations are a fig leaf, to be polite, with little purpose beyond the symbolic. Even more reason to shine a bright light on the prevalence of doping and the policies in place to regulate it.
Today's article does NOT argue that drug testing cannot be used to detect doping. It states that using the frequency of positive drug tests as an estimate of doping prevalence in the manner you proposed is flawed, as is detailed in the review by Hon and colleagues.
ReplyDeleteThe primary purpose of testing blood/urine samples is not to estimate the prevalence of doping but rather to identify individuals who are doping. Given this difference in focus - one being an estimate of a population-level parameter, the other looking at the likelihood of an individual-level binary variable (I.e. is this individual doping?) - it isn't actually as surprising as you make out that a methodology designed for the latter (catching dopers) operates poorly when applied to the former. It is this very issue that has presumably stimulated published studies of doping prevalence amongst athletes over the past decade, with even self-reporting surveys producing considerably higher estimates of doping prevalence than the frequency of positive doping tests.
Clearly, then, methods are available to approach both of the two issues highlighted, and the key to resolving this, then, is to appreciate that the optimal approach is not the same for these two issues, precisely because the parameters you are attempting to quantify are very different.
Simon-
ReplyDeleteThanks for your comment. A few replies.
1. You are correct, I was imprecise. I have edited to now state: "drug testing, as currently employed by anti-doping agencies, cannot be used ..."
2. We seem to be in violent agreement. My original piece was not an essay on methodology but a criticism of drug testing agencies for not employing methodologies which would allow for estimating the prevalence of doping and the effectiveness of anti-doping policies.
3. You write: "the optimal approach is not the same for these two issues, precisely because the parameters you are attempting to quantify are very different" -- which is pretty much the point of my original essay.
Thanks!
Yeah. In this respect, WADA are presumably somewhat between a rock and a hard place. There are science issues, which are easily overcome, and there are sports politics issues, which are not (ultimately because of the money involved). I don't think WADA could maintain the support of sports' governing bodies if they allowed the data they hold to be used to openly demonstrate to the public the extent to which the rules are being violated/ignored, which would then prevent WADA from being able to to carry out doping tests. Limiting doping, rather than quantifying it, seems to be WADA's primary aim (however much confirmation of the success of one necessitates the other) and, although many dopers evidently slip through the net, the mesh is getting smaller. It would take a very forward-thinking governing body, perhaps, to acknowledge the extent of the problem and thereby incur a loss of income in the short term in the hope that it was in the long-term interests of the sport. Perhaps we are starting to see that in cycling, but only after the sport had essentially bottomed out in terms of credibility - for many sports, the administrators maintain a very comfortable life based on the status quo.
ReplyDeleteOf course, this is all horribly frustrating if you'd like to know the truth. But a lot of sports fans actually seem to prefer not knowing, or even choose to ignore the evidence. I guess the governing bodies rely on that.