Maximum risk score: 9 points + sum of QT-drugs, Low risk: < 5
points, High risk: ≥ 5 points
*QTc prolongation: QTc ≥ 450 ms for males, ≥ 470 ms for females, or an
increase from baseline ECG by ≥ 30 ms.
A cutoff of 5 points revealed a good balance between sensitivity and
specificity (58% and 69% respectively), a PPV of 41% and an NPV of
82%. We also performed our calculation after removal of drugs from
CredibleMeds list 3 as a trigger for the risk score. Since these drugs
were not shown to be significant and were no longer calculated in the
risk score, removing them from the list of triggering medications would
help reduce the volume of alerts and make our risk score more accurate.
This resulted in a sensitivity of 68%, a specificity of 66%, a PPV of
45% and an NPV of 83%. Compared with the DDI warnings, these values
are more balanced and may help detect QTc-prolongation while reducing
false positive alerts.