Table 4. Four hypothetical pharmacogenetic tests for clozapine-induced agranulocytosis and their clinical impact.
| Test | Sensitivity | Size of HR group | P(A|LR) (1-NPV) | P(A|HR) (PPV) | Specificity | Clinical impact |
|---|---|---|---|---|---|---|
| A | 0.500 | 0.004 | 0.004 | 1 | 1 | No change in monitoring, but withhold clozapine from HR group |
| B | 0.600 | 0.200 | 0.004 | 0.024 | 0.803 | No change in monitoring |
| C | 0.850 | 0.100 | 0.0013 | 0.068 | 0.906 | Stop monitoring in LR group |
| D | 0.950 | 0.500 | 0.0008 | 0.015 | 0.504 | Stop monitoring in LR group |
Abbreviations: HR, high risk; LR, low risk; NPV, negative predictive value; PPV, positive predictive value.