Bernadette, maybe I’m misunderstanding your point, but the 14 year estimate is for patients 60-64 who receive a transplant (this might be a bit unclear as we wrote it though). Patients 60-64 on dialysis can expect 5.1 years of life, so that gives a 8.9 differential, which when you discount years by disability comes to 8.29 or about 8, which is our (admittedly imprecise) estimate. We don’t think it’s skewed in an optimistic direction though. To be clear, the 14-year overall estimate is 8 per transplant * 1.75 per marginal transplants created by starting a chain.
Patients 45-49 with a transplant have an average life expectancy of 22.8 years (8.3 if they’re on dialysis). But we’re not assuming they’re the median recipient.
I haven’t seen half-life outcomes broken out by living related vs. unrelated donors, but 5-year graft survival is similar. See p. 14 of the 2012 OPTN Report -- (http://srtr.transplant.hrsa.gov/annual_reports/2012/pdf/01_kidney_13.pdf). This makes sense because deceased donor organs are not worse primarily because of mismatching but because (besides the fact that they’re dead) the quality of donor pre-death is worse (they don’t go through rigorous screening; little health data is available; something caused them to die, etc.).
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.
Bernadette, maybe I’m misunderstanding your point, but the 14 year estimate is for patients 60-64 who receive a transplant (this might be a bit unclear as we wrote it though). Patients 60-64 on dialysis can expect 5.1 years of life, so that gives a 8.9 differential, which when you discount years by disability comes to 8.29 or about 8, which is our (admittedly imprecise) estimate. We don’t think it’s skewed in an optimistic direction though. To be clear, the 14-year overall estimate is 8 per transplant * 1.75 per marginal transplants created by starting a chain.
Patients 45-49 with a transplant have an average life expectancy of 22.8 years (8.3 if they’re on dialysis). But we’re not assuming they’re the median recipient.
I haven’t seen half-life outcomes broken out by living related vs. unrelated donors, but 5-year graft survival is similar. See p. 14 of the 2012 OPTN Report -- (http://srtr.transplant.hrsa.gov/annual_reports/2012/pdf/01_kidney_13.pdf). This makes sense because deceased donor organs are not worse primarily because of mismatching but because (besides the fact that they’re dead) the quality of donor pre-death is worse (they don’t go through rigorous screening; little health data is available; something caused them to die, etc.).
Here’s how you present the calculation
average half life of graft is 14.1 years across all transplants (which I’ve confirmed is what your defence data is discussing)
patients aged 60-65 on dialysis have life expectancy 5.2 years
therefore patients aged 60-65 on dialysis will gain 8.9 years from transplant.
I think that’s implausible for the reasons above.
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.