Table 4

Diagnostic performance characteristics of the ICD-10 N17x code in hospitalised patients with and without CKD using serum creatinine-based definitions of AKI as the reference standard*

Diagnostic performance characteristics (95% CI)
DefinitionPatients with CKDPatients without CKD
AKIN Stage 1Sn=35.6 (32.0 to 39.3)Sn=20.4 (19.4 to 21.4)
Sp=92.0 (90.2 to 93.5)Sp=98.6 (98.4 to 98.7)
PPV=74.4 (69.2 to 78.9)PPV=74.2 (72.1 to 76.2)
NPV=68.7 (66.1 to 71.1)NPV=85.9 (85.5 to 86.3)
 
RIFLE RiskSn=76.9 (65.4 to 85.5)Sn=54.8 (51.4 to 58.2)
Sp=83.5 (81.6 to 85.3)Sp=96.5 (96.3 to 96.7)
PPV=16.2 (12.5 to 20.8)PPV=26.2 (24.2 to 28.3)
NPV=98.9 (98.1 to 99.3)NPV=98.9 (98.8 to 99.1)
 
RIFLE InjurySn=75.6 (60.7 to 86.2)Sn=60.5 (56.2 to 64.5)
Sp=82.6 (80.7 to 84.4)Sp=96.2 (96.0 to 96.4)
PPV=10.1 (7.2 to 13.9)PPV=18.5 (16.8 to 20.5)
NPV=99.2 (98.6 to 99.6)NPV=99.4 (99.3 to 99.5)
 
RIFLE FailureSn=48.4 (42.2 to 54.6)Sn=63.1 (59.4 to 66.6)
Sp=86.4 (84.5 to 88.1)Sp=96.4 (96.3 to 96.6)
PPV=38.6 (33.4 to 44.2)PPV=24.8 (22.8 to 26.9)
NPV=90.4 (88.7 to 91.9)NPV=99.3 (99.2 to 99.4)
  • All values are presented as percentages (%).

  • *The ICD-10 N17× coding algorithm considered is all diagnoses.

  • AKI, acute kidney injury; CKD, Chronic kidney disease; ICD-10, International Classification of Diseases, tenth revision; NPV, negative predictive value; PPV, positive predictive value; Sn, sensitivity; Sp, specificity.