At 75, a marginal kidney may not beat staying on dialysis

Design

target trial emulation with monthly sequential trials, flexible parametric spline models, registry data 2000-2019

Population

64,036 waitlisted dialysis patients aged 20 and over in five European countries or regions; 39,244 transplanted

Primary outcome

five-year patient survival after deceased donor transplantation vs continued dialysis

Effect

standard-criteria donors favoured at all ages; expanded-criteria/donation after circulatory death at age 75: 59% (95% CI 51-66) vs 55% (54-55), HR 0.97 (0.70-1.33)

A target trial emulation using European Renal Association Registry data from Catalonia, Denmark, France, Norway and the UK, covering 64,036 waitlisted dialysis patients between 2000 and 2019, of whom 39,244 were transplanted. Five-year survival after deceased donor transplantation was compared with continued dialysis in monthly sequential trials, split by donor criteria and retrieval type.

Standard-criteria kidneys — whether donation after brain death or after circulatory death — were associated with better five-year survival than continued dialysis at every recipient age. The benefit of expanded-criteria kidneys narrowed as recipients aged, and for expanded-criteria donation after circulatory death it disappeared: among 75-year-olds, five-year survival was 59% (95% CI 51-66) after transplantation against 55% (54-55) on dialysis, hazard ratio 0.97 (0.70-1.33). That group also had threefold higher early post-transplant mortality.

This is the conversation the nephrology clinic is already having badly. An older patient told that a kidney is available hears 'better than dialysis' regardless of which kidney it is. These numbers let that discussion distinguish between a standard kidney, where the survival case is clear at any age, and a marginal one in a 75-year-old, where the honest answer is that it may cost more life in the first year than it returns over five.

• Ask which donor category an offer falls into before framing it as a survival benefit
• Front-load the early mortality risk in the consent conversation for older recipients of marginal kidneys
• Quality of life off dialysis is a legitimate reason to accept a kidney that offers no survival gain — but say that is the reason
• These are European registry data; Indian deceased-donor practice and dialysis outcomes differ enough that the numbers do not transfer directly

Why it matters

It separates 'a kidney' from 'this kidney' in a conversation that currently treats any offer as an unambiguous gain.

Don't overread it

This is an emulation of a trial, not a trial — unmeasured differences between those transplanted and those who stayed on dialysis can still bias it.

The statistics, in plain English

Target trial emulation reconstructs a randomised comparison from registry data by repeatedly asking, month by month, who was eligible for a transplant and who actually got one. It handles the main trap — that people who get transplanted were healthier to begin with — better than a simple comparison, but it cannot fully remove it. The 75-year-old estimate carries an interval from 51% to 66% because relatively few patients contribute to it.

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