Gill JS et al. (2005) The impact of waiting time and comorbid conditions on the survival benefit of kidney transplantation. Kidney Int 68: 2345–2351

A growing disparity between supply and demand of organs for kidney transplantation is expected to increase waiting times to more than a decade by 2010. Excluding candidates who would derive no survival benefit from transplantation would maximize efficient use of limited resources. A longitudinal study of mortality of dialysis patients on waiting lists for transplantation in the US, however, has shown that an anticipated waiting time of as long as 3 years is not a suitable exclusion criterion.

The analysis, which used data from the US Renal Data System, included patients who underwent kidney or multiorgan transplantation from live or deceased donors within 3 years of joining the waiting list (n = 28,234) and those who remained on dialysis (n = 35,549).

Projected survival benefit from transplantation for all graft recipients was 9.8 years. As expected, anticipated survival benefit was less in those with comorbid conditions, such as diabetes (6 years), ischemic heart disease (7.9 years) and congestive heart failure (6.7 years), and decreased as age increased. Compared with subjects with waiting times of 1 year, the survival benefit for graft recipients who waited 3 years was only slightly reduced (7.1 years vs 5.6 years). Because of the greater likelihood of death as dialysis-dependent waiting times increased, the relative risk of mortality among transplant recipients after 12 months was less among those who waited longest (0.43 after 1 year vs 0.34 after 3 years).

It therefore seems that preferential organ allocation to patients with short anticipated waiting times and no comorbidities would not significantly improve survival benefit. The authors do, however, suggest excluding potential graft recipients from the waiting list if their life expectancy on dialysis is projected to be less than the time taken to secure a suitable donor organ.