Remember, nothing is alleged to--or can have--happened to all of MLB over some one or two seasons: the claim is that PEDs were being used at a slowly but steadily increasing rate (and thus "distorting records") from very roughly 1980 through the present. Were that so, or anything like it, we would expect to see a clear long-term uptrend during this period. But we don't: we see a nearly flat line that, if anything, slopes slightly down. The "boost" just isn't there. But that doesn't seem to stop anyone from talking about it.
One drawback to Brennan’s study is that, unlike Kouri’s, there was evidence of attempted deception. Several people had to be excluded from the non-users’ group because they were either definitely on steroids (they failed the urine test), or probably on steroids (in the researchers’ words, they had “implausibly high muscularity and low body fat despite denial of AAS use”). However, even if a couple of users slipped in, they probably didn’t skew the data too much. The sample size for nonusers was big enough (131 people) that a few bad apples wouldn’t spoil the whole bunch, and the researchers were excluding suspiciously jacked people anyways, so if a few users did slip in, they apparently weren’t swole enough to raise any red flags.
There is now significant evidence to support that systemic corticosteroids help not only in arresting the progression of vitiligo, but may also help repigment affected skin. Periodic evaluation, adjustment of the dose, and monitoring of side effects are important in avoiding long-term complications. Since autoimmunity against melanocytes is the predominant hypothesis regarding the pathogenesis of non-segmental vitiligo, systemic corticosteroids should not be considered for segmental vitiligo or focal limited vitiligo, in which autoimmunity likely does not play a significant role. More studies using systemic corticosteroids for vitiligo need to be performed to better understand their efficacy and safety for this disorder.