Decreasing incidence of renal replacement therapy over time at the critical 50-59-year age range suggests a role for nephroprotective therapy in ADPKD.

To the Editor: Spithoven et al.1 conclude that the increased age at onset of renal replacement therapy (RRT) over time is most likely due to an increased access for elderly ADPKD patients or lower competing risk prior to the start of RRT rather than the consequence of effective emerging renoprotective treatments for ADPKD. However, the lower incidence of RRT expressed per million of the age-related population (p.m.a.r.p.) in the most recent period for the crucial age range 50–59, when the incidence peaks, suggests a potential role for medical therapy. In 1991–95, the incidence of RRT peaked at age 50–54 and then fell. We have redrawn Figure 1 without 1991–95 data because the early peak of incidence and later decrease is compatible with a lack of access to RRT because of age, as at the time age-related criteria were still in place at many centers. The figure shows that for the most recent time periods (1996–2010), unmarred by potential lack of access to RRT, incidence of RRT is 6–10% lower in 2006–2010 than in 1996–2000, for the 50 to 59 decade, remains lower until age 69, and is higher thereafter. Thus, we agree with the authors that an increased access for elderly ADPKD patients or lower competing risk prior to the start of RRT indeed contributes to increase age at RRT. However, on the basis of incidence data, we respectfully disagree on the lack of potential contribution of effective emerging renoprotective treatments for ADPKD. This hypothesis is in agreement with recent US data assessing age at end-stage renal disease.2