Table 5:

Effect of methylprednisolone versus placebo on the risk of acute kidney injury in a subsample of patients with serial postoperative serum creatinine assessments (restricted to the 4824 patients who were randomly assigned on or after Mar. 1, 2012)

VariableNo. (%) of events*Relative risk (95% CI)
Methylprednisolone
n = 2405
Placebo
n = 2419
UnadjustedAdjusted
Acute kidney injury (KDIGO guideline definition)§15832 (34.6)819 (33.9)1.02 (0.94 to 1.10)1.02 (0.92 to 1.12)
Acute kidney injury for ≥ 2 days538 (22.4)549 (22.7)0.99 (0.89 to 1.09)0.98 (0.87 to 1.10)
Acute kidney injury for ≥ 3 days**358 (14.9)363 (15.0)0.99 (0.87 to 1.13)0.98 (0.85 to 1.14)
  • Note: CI = confidence interval, KDIGO = Kidney Disease Improving Global Outcomes.

  • * At least 1 postoperative serum creatinine measurement in the first 7 days after surgery was available for 98.2% of patients. Patients with no serum creatinine measurements in the 7-day period after surgery (and who did not receive dialysis within 30 days of surgery) were assumed to not have acute kidney injury (n = 89; 49 [2.0%] in the methylprednisolone group and 40 [1.7%] in the placebo group). Of these 89 patients, 43 (48.3%) died within 0, 1 or 2 days after surgery (23 [46.9%] in the methylprednisolone group and 20 [50.0%] in the placebo group).

  • A modified Poisson regression model was used without adjustment for covariates or accounting for centre.

  • Adjusted for 10 prespecified covariates: age (yr); sex; left ventricular function < 50%; diabetes; preoperative estimated glomerular filtration rate < 60 mL/min/1.73m2; prerandomization use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, statins, or diuretics; surgery type (isolated valve [referent], isolated coronary artery bypass grafting [CABG], CABG and valve, or other); and evidence of nonelective surgery (defined as preoperative use of inotropes or vasopressors, preoperative use of an intra-aortic balloon pump or ventricular assist device, or evidence of myocardial infarction in the 30 days before surgery).

  • § Defined as an increase in the serum creatinine concentration (from the preoperative value) of ≥ 0.3 mg/dL [≥ 26.5 μmol/L] within 48 hours of surgery, or ≥ 50% within 7 days of surgery, or receipt of dialysis within 30 days after surgery. Results were similar in a sensitivity analyses that imputed missing postoperative creatinine data with a peak value obtained in the first 14 days after surgery (available for 50 of the 89 patients missing outcome data for the KIDIGO guideline definition): adjusted relative risk 1.02 (95% CI 0.93 to 1.12).

  • Defined as an increase in serum creatinine concentration (from the preoperative value) of ≥ 0.3 mg/dL [≥ 26.5 μmol/L] or ≥ 50%, evident on at least 2 separate days within 7 days of surgery, or receipt of dialysis within 30 days after surgery.

  • ** Defined as an increase in serum creatinine concentration (from the preoperative value) of ≥ 0.3 mg/dL [≥ 26.5 μmol/L] or ≥ 50%, evident on at least 3 separate days within 7 days of surgery, or receipt of dialysis within 30 days after surgery.