Table 4.
A priori probabilities of outcomes by diagnostic approach
|
A priori probability (%)
|
||||
|---|---|---|---|---|
| Clinical strategy (FNAB assumptions) | Surgery for benign nodule | Observation for benign nodule | Surgery for cancer | Observation for cancer |
| Routine observation | ||||
| A | 0.0 | 92.0 | 0.0 | 8.0 |
| B | 0.0 | 92.0 | 0.0 | 8.0 |
| Routine FNAB | ||||
| A | 24.1 | 67.9 | 7.8 | 0.2 |
| B | 13.8 | 78.2 | 7.9 | 0.1 |
| FNAB only if mCa | ||||
| A | 2.7 | 89.3 | 3.5 | 4.5 |
| B | 1.6 | 90.4 | 3.5 | 4.5 |
| FNAB only if hypo-plus | ||||
| A | 7.8 | 84.2 | 7.0 | 1.0 |
| B | 4.5 | 87.5 | 7.2 | 0.8 |
These estimates are predicated on baseline model parameters (Table 1). A, Set of conservative FNAB parameter estimates (95% FNAB sensitivity and specificity; 10% likelihood of persistently inadequate FNAB; and 15% likelihood of indeterminate FNAB). B, Set of more optimistic FNAB parameter estimates (98% FNAB sensitivity and specificity; 5% likelihood of persistently inadequate FNAB; and 10% likelihood of indeterminate FNAB). mCa, Microcalcifications; hypo-plus, hypoechoic plus at least one other ultrasonographic risk factor.