Randomised controlled trials (RCTs) in perioperative settings that compared N-acetylcysteine with placebo for adults who underwent major surgery were eligible for inclusion, provided radio contrast was not used. The primary outcomes for the review were mortality and acute renal failure that required dialysis. Other outcomes of interest included rates of increase in serum creatinine more than 25% above baseline (or more than 0.50mg per dL), surgical re-exploration for bleeding, length of intensive care unit stay and amount of allogeneic blood transfusion required. Studies of N-acetylcysteine for patients with sepsis, acute respiratory distress syndrome or radio contrast nephropathy were excluded, as were studies in which N-acetylcysteine was administered as part of a multi-oxidant supplement.
Participants in studies in the review underwent elective cardiac surgery, abdominal aneurysm repair or abdominal cancer surgery. Most had normal renal function preoperatively, although some of the cardiac surgery studies were restricted to participants with pre-existing renal impairment. N-acetylcysteine was in most cases given intravenously through the whole peri-operative period at a mean dose of about 15,300 mg (range 2,400 to 35,000 mg per 75kg patient); some studies used an oral dose pre-operatively. Controls in most cases received an equivalent volume of intravenous 5% dextrose or 0.9% saline.
Two reviewers checked the eligibility of selected trials, but the authors stated neither how the papers were initially selected for the review nor how many reviewers performed the selection.