Positive (PPV) and negative predictive values (NPV) of the simple traffic light grading for any fibrosis or cirrhosis in the model development cohorta
| Setting | Parameter | Predictive value | Fibrosis | Cirrhosis |
|---|---|---|---|---|
| STL | Simple TL | |||
| Hospital setting prior probability: cirrhosis 39%, fibrosis 82% | Red | PPV | 0.96 | 0.69 |
| Red/amber | PPV | 0.88 | 0.46 | |
| Green | NPV | 0.50 | 0.97 | |
| Low prevalence community prior probability: cirrhosis 4%, fibrosis 8% | Red | Est PPV | 0.31 | 0.13 |
| Red/amber | Est PPV | 0.12 | 0.05 | |
| Green | Est NPV | 0.98 | 1.00 | |
| Higher prevalence community prior probability: cirrhosis 10%, fibrosis 20% | Red | Est PPV | 0.57 | 0.27 |
| Red/amber | Est PPV | 0.29 | 0.13 | |
| Green | Est NPV | 0.95 | 0.99 | |
| mSTL | Modified TL | |||
| Hospital setting prior probability: cirrhosis 39%, fibrosis 82% | Red | PPV | 0.99 | 0.73 |
| Red/amber | PPV | 0.91 | 0.48 | |
| Green | NPV | 0.59 | 0.99 | |
| Low prevalence community prior probability: cirrhosis 4%, fibrosis 8% | Red | Est PPV | 0.63 | 0.15 |
| Red/amber | Est PPV | 0.17 | 0.04 | |
| Green | Est NPV | 0.99 | 1.00 | |
| Higher prevalence community prior probability: cirrhosis 10%, fibrosis 20% | Red | Est PPV | 0.84 | 0.31 |
| Red/amber | Est PPV | 0.38 | 0.13 | |
| Green | Est NPV | 0.96 | 1.00 | |
↵a As the prevalence of fibrosis/cirrhosis in a primary care population with suspected liver disease was not known, estimated PPV (Est PPV) and NPV (Est NPV) values were calculated for a range of prevalences: fibrosis (8–20%) and cirrhosis (4–10%). These ranges of risk might be expected in patients with harmful alcohol consumption or known fatty liver and steatohepatitis.