Table 2.
Characteristics of external validation studies and model performance in validations (N = 17)
| Study | Model validated | Independent | Validation type | Country | Population | GFR mean | N total, No. of events | Outcome | Time frame (years) | Model updated | C-statistic | Calibration | Updated model presented |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| General CKD | |||||||||||||
| Schroeder et al. [24] | KPNW model (Johnson) | No | External | USA | General CKD Stages 3 and 4 | 48 | 16 553, 360 | RRT | 5 | Baseline hazard recalibrated to Colorado | 0.95 | Plot | No |
| Lennartz et al. [19] | KFRE 4v (Tangri) | No | External | Germany | General CKD Stages 2–4 | 46 | 565, 52 | RRT | 3 | Baseline hazard, addition ultrasound parameters | 4v, update: 0.91, 0.91 | Plot | Formula |
| Tangri et al. [18] | KFRE 4v and 8v (Tangri) | No | External | >30 countries | General CKD Stages 3–5 | 46 | 721 357, 23 829 | RRT | 2, 5 | Baseline hazard recalibrated to Europe | 4v, 8v: 0.88, 0.88 | Plot | Formula and web calculator |
| Grams et al. [16] | KFRE 4v (Tangri) | Yes | External | USA | CKD, GFR 20–65a | – | 1094, – | RRT | 1, 5 | No | 0.83 | – | – |
| Marks et al. [28] | Model 7 (Marks) | No | Temporal | Scotland | General CKD Stages 3–5 | 47 | 18 687, 222 | RRT | 5 | No | 0.96 | Plot, test | – |
| KFRE 3v and 4v (Tangri) | Yes | External | Scotland | General CKD Stages 3–5 | 47 | 18 687, 222 | RRT | 5 | No | 3v, 4v: 0.94, 0.95 | Plot | – | |
| Levin et al. [30] | KFRE 8v (Tangri) | No | External | Canada | General CKD Stages 3b–4 | 28 | 2402, 142 | RRT | 1 | Coefficients re-estimated, biomarkers added | 8v, update: 0.86, 0.87 | – | HRs |
| Drawz et al. [32] | VA risk score (Drawz) | No | Geographic | USA | General CKD Stage 4 and 5b | 25 | 819, 33 | GFR <15, RRT | 1 | No | 0.82 | – | – |
| KFRE 8v (Tangri) | Yes | External | USA | General CKD Stage 4 and 5b | 25 | 2684, 110 | GFR <15, RRT | 1 | No | 0.78 | – | – | |
| Peeters et al. [17] | KFRE 3v, 4v, and 8v (Tangri) | Yes | External | The Neth- erlands | General CKD Stages 3–5 | 33 | 595, 114 | RRT | 5 | No | 3v, 4v, 8v: 0.88, 0.88, 0.89 | Plot, test | – |
| Tangri et al. [34] | KFRE 3v, 4v, and 8v (Tangri) | No | External | Canada | General CKD Stages 3–5 | 31 | 4942, 1177 | RRT | 1, 3, 5 | No | 3v, 4v, 8v: 0.79, 0.83, 0.84 | Plot, test | – |
| Landray et al. [35] | CRIB score (Landray) | No | External | UK | General CKD Stages 3–5 | 22 | 213, 66 | RRT | – | No | 0.91 | Plot | – |
| Specified renal disease | |||||||||||||
| Knoop et al. [21] | ARR score (Berthoux) | Yes | External | Norway | IgA nephropathy | – | 1134, 320 | Death, RRT | 5, 10, 15 | Coefficients re-estimated, age and GFR added | 0.79 update: 0.89 | – | Formula |
| Mohey et al. [22] | ARR score (Berthoux) | No | External | France | Secondary IgA nephropathy | 82 | 74, 19 | GFR <15, death | 10, 20 | No | – | – | – |
| Tanaka et al. [46] | Tanaka score | No | External | Japan | IgA nephropathy | – | 702, 85 | RRT | 5 | No | 0.89 | Plot, test | – |
| Xie et al. [47] | Goto score | Yes | External | China | IgA nephropathy | 88 | 619, 67 | ESRD | 2, 5, 10 | No | 0.82 | – | – |
| RENAAL score (Keane) | Yes | External | China | IgA nephropathy | 88 | 619, 67 | ESRD | 2, 5, 10 | No | 0.79 | – | – | |
| ARR score (Berthoux) | Yes | External | China | IgA nephropathy | 88 | 619, 67 | ESRD | 2, 5, 10 | No | 0.73 | – | – | |
| Berthoux et al. [48] | ARR score (Berthoux) | No | Temporal | France | IgA nephropathy | – | 250, 38 | Death, RRT | 10, 20 | No | – | – | – |
| Bjorneklett [20] | Goto score | Yes | External | Norway | IgA nephropathy | 67 | 633, 146 | RRT | 10, 20 | Coefficients re-estimated, classification simplified | – | – | No |
| Magistroni et al. [54] | Magistroni score | No | External | Italy | IgA nephropathy | – | 73, 8 | RRT | 10 | No | – | – | – |
a
Hypertensive CKD population.
b
Population of veterans ≥65 years old. v, variable; (e)GFR, (estimated) glomerular filtration rate in mL/min/1.73 m2; EPV, events per variable/candidate predictor; ‘–’ not reported. The time-frame for which the model performance and other model specifics are reported in bold in the table.