Providing Guidance in the Dark: Rare Renal Diseases and the Challenge to Improve the Quality of Evidence

Davide Bolignano; Evi V. Nagler; Wim Van Biesen; Carmine Zoccali


Nephrol Dial Transplant. 2014;29(9):1628-1632. 

In This Article

Planning Interventional Studies in Rare Diseases

When designing a drug trial in a rare disease, a detailed background on the pharmacology of a drug being tested is desirable and pharmacology studies can also help to identify sources of heterogeneity in patients affected by the disease. For rare diseases with very long course, the use of surrogate end points may be acceptable but the relationship between these surrogates and clinical efficacy should be preliminarily established to properly evaluate the balance of risks and benefits.

An example of validated surrogate end point is cyst volume in patients with ADPKD. Kidney enlargement resulting from the expansion of cysts is a quantifiable parameter and higher rates of kidney enlargement reflect a more rapid decrease in renal function.[19]