Those with HIV and using nandrolone may not exactly go around advertising their HIV status, and then additionally telling people that their dick doesn't work (deca dick). Society (wrongly) would probably bash them for trying to have sex. So their probably keep quiet (moreso than others).
I'm not saying this is the way to treat others, or that its politically correct etc. I'm just mentioning this to point out that the sample may be highly biased for these reasons.
