Thanks for your reply.
The JAMA article you cite is not a good one for this discussion, I think, because the median followup was just 6.3 years. The mortality curves for donors and properly matched controls don't start moving apart until about 10 years. At 15 years, the difference is quite pronounced. At 20 years post donation, donors are looking at 50% increased mortality compared to properly matched controls.
Kidney donation is still a huge benefit for recipients, and may be a net benefit, but it is a much bigger risk (I believe) for donors than has been portrayed. Yet major donor web sites (Stanford, Maryland Medical Center) haven't caught up to the research.
The claim that kidney donation does not affect donor survival is based mainly on [Ibrahim NEJM 2009], which has a very serious flaw. In that study donors are matched to controls from the general population, which is significantly less healthy than screened donors. In contrast [Mjoen 2013] found very significant reduction in survival rates for donors. A footnote on this EA page claims that [Mjoen 2013] also makes an error in matching to controls with the control group being younger, but the [Mjoen 2013] authors address this concern here:
To summarize, "Drs. Kaplan and Ilahe argue that the difference in mortality between the living kidney donors and controls in our study was due to differences in age between the two groups. There seems to be a misunderstanding about the statistical methods used. They refer to differences in age at baseline, that is, before any adjustment or matching was performed." Refer to the link for more detail.
At this point I would say that the evidence strongly favors the proposition that kidney donation significantly negatively affects donor survivial.