N-acetylcysteine in the prevention of radiocontrast-induced nephropathy: Clinical trials and end points

N-acetylcysteine (NAC) has been suggested to prevent
radiocontrast-induced nephropathy (RCIN) in patients with a reduced
renal function. However, clinical studies have not been
demonstrating this effect consistently. Also, reviews and
meta-analyses dealing with the question of prevention of RCIN by
NAC have been controversial. Nearly all investigators used serum
creatinine as surrogate end point of their trials, and changes in
serum creatinine concentrations are thought to reflect the extent
of renal injury as primary outcome. In a recent study, an effect of
NAC on creatinine values and estimated glomerular filtration rate
without any effect on cystatin C levels has been shown in
volunteers with a normal renal function. Therefore, before renal
protective effects of NAC in RCIN are proposed, any direct effects
of NAC on creatinine, urea, and estimated glomerular filtration
rate should be addressed. In future trials, the glomerular
filtration rate should preferentially be measured directly, or at
least additional markers of the renal function ( e. g., serum
cystatin C) have to be assessed. Furthermore, additional `hard' end
points, i.e., hospital morbidity, mortality, or dialysis
dependency, should be considered in the design of future studies of
RCIN. Copyright (C) 2004 S. Karger AG, Basel.