Contrast-induced nephropathy and its prevention: What do we really know from evidence-based findings?

INTRODUCTION Contrast-induced acute kidney injury, also referred to as contrast-induced nephropathy (CIN), is a potentially serious renal complication associated with the use of iodinated contrast media (CM) in patients at risk. With the dramatic growth in contrast-enhanced imaging services worldwide, including procedures involving exposure to iodinated CM, efforts to reduce the occurrence of CIN have received considerable attention in recent years. To date, these efforts have met with little success since the 12% prevalence of CIN today remains unchanged from 2 decades ago. METHODS We conducted a systematic literature review of the most recent evidence available from published reports of contemporary (2000-2008) prospective, randomized, controlled trials that have investigated CIN either by comparing CM or by comparing preventive strategies. The objective was to critically review the findings in light of several aspects of study design and then to establish a set of parameters for consideration in the planning of future CIN trials so as to optimize the strength of evidence obtained. RESULTS Whether future CIN trials are investigating comparative CM nephrotoxicity or dealing with prophylactic strategies for risk reduction, the complexities that must be addressed include a standardized definition of CIN, appropriate timing of SCr measurements with timing standardized for all subjects in a given study population, awareness of study population risk profile, hydration protocols, and pharmacological prophylactic strategies. CONCLUSIONS Large, well-designed trials (ideally with hard clinical outcome measures) that consider all the complexities involved in CIN and its prevention are needed before the clinical community has the evidence-based direction required for optimized patient care.