Table 2.
Diagnostic performance characteristics of three different algorithms for ICD-10 code N17× using four different serum creatinine-based definitions of AKI as the reference standard
| Diagnostic performance characteristics (95% CI) |
|||
|---|---|---|---|
| Diagnostic coding algorithm | Definition | Emergency Department Cohort | Hospitalised Cohort |
| All diagnoses | AKIN Stage 1 | Sn=7.2 (6.6 to 8.0) | Sn=21.8 (20.9 to 22.8) |
| Sp=99.9 (99.8 to 99.9) | Sp=98.4 (98.2 to 98.5) | ||
| PPV=90.4 (87.2 to 92.8) | PPV=74.2 (72.3 to 76.1) | ||
| NPV=86.2 (85.8 to 86.5) | NPV=85.3 (84.9 to 85.6) | ||
| RIFLE Risk | Sn=30.4 (26.5 to 34.7) | Sn=56.4 (53.2 to 59.7) | |
| Sp=99.2 (99.1 to 99.3) | Sp=96.0 (95.8 to 96.2) | ||
| PPV=33.8 (29.5 to 38.4) | PPV=24.7 (22.8 to 26.6) | ||
| NPV=99.1 (99.0 to 99.2) | NPV=98.9 (98.8 to 99.1) | ||
| RIFLE Injury | Sn=37.4 (32.1 to 43.1) | Sn=61.6 (57.5 to 65.5) | |
| Sp=99.1 (99.0 to 99.2) | Sp=95.6 (95.4 to 95.8) | ||
| PPV=25.8 (21.9 to 30.2) | PPV=17.3 (15.7 to 19.0) | ||
| NPV=99.5 (99.4 to 99.6) | NPV=99.4 (99.3 to 99.5) | ||
| RIFLE Failure | Sn=30.2 (26.4 to 34.2) | Sn=59.1 (55.9 to 62.3) | |
| Sp=99.2 (99.2 to 99.3) | Sp=96.1 (95.9 to 96.3) | ||
| PPV=37.3 (32.9 to 42.0) | PPV=26.9 (25.0 to 28.9) | ||
| NPV=99.0 (98.9 to 99.1) | NPV=99.0 (98.9 to 99.1) | ||
| Main diagnosis/most responsible diagnosis | AKIN Stage 1 | Sn=4.1 (3.6 to 4.6) | Sn=5.1 (4.6 to 5.7) |
| Sp=100.0 (99.9 to 100.0) | Sp=99.9 (99.8 to 99.9) | ||
| PPV=94.7 (91.0 to 97.0) | PPV=90.7 (87.4 to 93.2) | ||
| NPV=85.8 (85.4 to 86.1) | NPV=82.9 (82.5 to 83.3) | ||
| RIFLE Risk | Sn=21.4 (17.9 to 25.3) | Sn=18.7 (16.2 to 21.4) | |
| Sp=99.6 (99.6 to 99.7) | Sp=99.4 (99.3 to 99.5) | ||
| PPV=44.5 (38.2 to 51.0) | PPV=42.5 (33.7 to 47.5) | ||
| NPV=99.0 (98.9 to 99.1) | NPV=98.1 (98.0 to 98.3) | ||
| RIFLE Injury | Sn=27.9 (23.1 to 33.3) | Sn=22.8 (19.5 to 26.4) | |
| Sp=99.6 (99.6 to 99.7) | Sp=99.3 (99.2 to 99.4) | ||
| PPV=36.1 (30.2 to 42.6) | PPV=33.3 (28.7 to 38.1) | ||
| NPV=99.4 (99.3 to 99.5) | NPV=98.9 (98.7 to 99.0) | ||
| RIFLE Failure | Sn=22.0 (18.7 to 25.7) | Sn=22.9 (20.3 to 25.8) | |
| Sp=99.6 (99.5 to 99.7) | Sp=99.5 (99.5 to 99.6) | ||
| PPV=51.1 (44.6 to 57.5) | PPV=54.4 (49.4 to 59.3) | ||
| NPV=98.9 (98.7 to 99.0) | NPV=98.1 (98.0 to 98.3) | ||
| Admission diagnosis | AKIN Stage 1 | n/a | Sn=15.8 (15.0 to 16.7) |
| Sp=99.2 (99.1 to 99.3) | |||
| PPV=81.6 (79.4 to 83.6) | |||
| NPV=84.5 (84.1 to 84.8) | |||
| RIFLE Risk | Sn=43.1 (39.9 to 46.4) | ||
| Sp=97.5 (97.3 to 97.6) | |||
| PPV=28.5 (26.2 to 31.0) | |||
| NPV=98.6 (98.5 to 98.8) | |||
| RIFLE Injury | Sn=48.3 (44.2 to 52.4) | ||
| Sp=97.2 (97.0 to 97.4) | |||
| PPV=20.5 (18.4 to 22.8) | |||
| NPV=99.2 (99.1 to 99.3) | |||
| RIFLE Failure | Sn=47.4 (44.2 to 50.6) | ||
| Sp=97.6 (97.5 to 97.8) | |||
| PPV=32.6 (30.2 to 35.2) | |||
| NPV=98.7 (98.6 to 98.8) | |||
All values are presented as percentages (%).
To convert serum creatinine from μmol/l to mg/dl divide by 88.4.
AKI, acute kidney injury; ICD-10, International Classification of Diseases, tenth revision; NPV, negative predictive value; PPV, positive predictive value; Sn, sensitivity; Sp, specificity; n/a, not applicable.