Expected lifespan can vary from graft survival half-life both because half-lives are different from averages and (moreso) because most patients end up surviving graft failure and going back on dialysis or getting another transplant (thus extending life further).
We used the 60-64 age as the baseline for the calculation because (1) it’s fairly typical of when patients develop ESRD; (2) the life-spans from both dialysis and transplant treatments fit the average transplant candidate; and (3) the transplant survival figure included both living and deceased, so it skewed conservative compared to a figure that only included living, which gave us a margin of error to avoid bias towards overoptimism.
Got it! Thanks for explaining that, and I do think we wrote it in a confusing way (sorry!). There are two separate facts --1. the half-life for all living donor grafts is 14.2 years (figure 6.7 here http://srtr.transplant.hrsa.gov/annual_reports/2012/pdf/01_kidney_13.pdf). 2. Expected lifespan for those who receive any kidney transplant between the years of 60 and 64 in particular is 14.0 years. (See p. 266 here—http://www.usrds.org/2013/pdf/v2_ch5_13.pdf).
Expected lifespan can vary from graft survival half-life both because half-lives are different from averages and (moreso) because most patients end up surviving graft failure and going back on dialysis or getting another transplant (thus extending life further).
We used the 60-64 age as the baseline for the calculation because (1) it’s fairly typical of when patients develop ESRD; (2) the life-spans from both dialysis and transplant treatments fit the average transplant candidate; and (3) the transplant survival figure included both living and deceased, so it skewed conservative compared to a figure that only included living, which gave us a margin of error to avoid bias towards overoptimism.