Intravenous N-acetylcysteine for the PRevention Of Contrast-induced nephropathy – a prospective, single-center, randomized, placebo-controlled trial. The INPROC trial

Introduction
Contrast-induced nephropathy (CIN) is a common clinical problem that is growing in importance as an increasing number of tests and procedures which utilize contrast media (CM) are performed.

Aim
To evaluate the efficacy of intravenous N-acetylcysteine (NAC) for prevention of CIN after diagnostic and/or interventional procedures requiring CM administration.

Material and methods
In a prospective, single-center, randomized, placebo-controlled trial the preventive effects of N-acetylcysteine were evaluated in 222 patients undergoing elective angiography and/or angioplasty. Patients were randomly assigned to receive either NAC or placebo. All patients received intravenous hydration with normal saline before and after catheterization. Serum creatinine (SCr) and estimated glomerular filtration rate were assessed at baseline, at 48–72 h and 10–15 days after CM administration. Contrast-induced nephropathy was defined as an increase in SCr of at least 44 µmol/l (0.5 mg/dl) or an increase of ≥ 25% of the baseline value 48–72 h after CM administration.

Results
Contrast-induced nephropathy occurred in 30 of 222 patients (13.5%): 9 of 108 patients in NAC (8.3%) and 21 of 114 patients in the control group (18.4%; p = 0.0281). The multivariate Cox analysis revealed that elevated SCr at 10–15 days (HR = 2.69; p = 0.018) and baseline SCr level (HR = 1.009; p = 0.015) were independent prognostic variables for adverse events during follow-up.

Conclusions
Our findings suggest that intravenous NAC along with intravenous hydration may help prevent declining renal function after CM exposure. Elevated SCr level 10–15 days after CM administration was associated with increased risk of adverse events in long-term observation, while elevated SCr within 72 h was not. Measuring SCr at least 10 days after exposure to CM may provide a better outcome measure.