Table 2.

Actual AKI misclassification rates using baseline serum creatinine estimation methods

Estimation MethodaOveralleGFR < 60 ml/min per 1.73 m2 (n=1118)eGFR ≥ 60 ml/min per 1.73 m2 (n=5384)
Single eGFR 7512.3 (11.5–13.2)40.5 (37.6–43.5)6.5 (5.8–7.2)
Basic multiple imputation10.0 (9.3–10.8)19.1 (16.8–21.5)8.1 (7.4–8.9)
Basic multiple imputation with SCr9.3 (8.6–10.0)13.9 (11.9–16.1)8.3 (7.6–9.1)
Full multiple imputation11.3 (10.6–12.1)28.3 (25.7–31.0)7.8 (7.1–8.6)
Full multiple imputation with SCr9.0 (8.3–9.7)15.3 (13.3–17.6)7.7 (7.0–8.4)
  • Misclassification rates (%) with 95% Wilson confidence intervals for each method are shown for the overall group. Estimated GFR based on minimum serum creatinine during the first 7 days of hospitalization. All multiple-imputation groups were compared with single eGFR 75 as the reference group. All differences in misclassification were statistically significant (P<0.001) except for the full multiple imputation versus single eGFR 75 in the overall comparison (P=0.06). eGFR, estimated GFR; eGFR 75, eGFR = 75 ml/min per 1.73 m2; SCr, serum creatinine.

  • a Basic multiple imputation = three-variable multiple imputation; basic multiple imputation with SCr = basic three-variable multiple imputation plus minimum inpatient serum creatinine; full multiple imputation = full-variable multiple imputation; full multiple imputation with SCr = full variable multiple imputation plus minimum inpatient serum creatinine.