Assessment of Drug-Induced QTc Prolongation in Mental Health Practice: Validation of an Evidence-Based Algorithm

Figures & data

Figure 1 Schematic representation of the study process.

Abbreviation: CVI=Content Validity Index.

Table 1 I-CVI Scores of the Decision Steps in the QTcI Prolongation Algorithm

	Minimum Mean Score (out of 4)	Maximum Mean Score (out of 4)	Average I–CVI (out of 1)
Appropriateness of the QTcIPA decision steps	3.68	3.83	0.95
Safety of the QTcIPA decision steps	3.7	3.83	0.95
Reliability of the references used in the QTcIPA decision steps	3.57	3.73	0.94

Abbreviations: QTcIPA, corrected QTc interval prolongation algorithm; I-CVI, item-level content validity index.

Figure 2 I-CVI scores for the appropriateness of algorithm decision steps.

Notes: Q1=Question 1: Assessing the drug using CredibleMeds^®; Q2=Question 2: Assessing the drug dose, route, and drug interactions; Q3=Question 3: Assessing the risk by calculating the patient’s QTc prolongation score; Q4=Question 4: Assessing the need for ECG monitoring based on the QTc risk score; Q5=Question 5: Recommending therapy if the risk score ≤ 7 points; Q6=Question 6: Assessing baseline ECG if risk score ≥ 7 points; Q7=Question 7: If ECG shows QTc ≥ 500 ms, avoid therapy and consider cardiac consultation; Q8=Question 8; If ECG shows QTc ≤ 500 ms, recommend therapy with follow up ECG and physical exam at specified cases.

Figure 3 I-CVI scores for the safety of the QTc Prolongation Algorithm decision steps.

Notes: Q1=Question 1: Assessing the drug using CredibleMeds^®; Q2=Question 2: Assessing the drug dose, route, and drug interactions; Q3=Question 3: Assessing the risk by calculating the patient’s QTc prolongation score; Q4=Question 4: Assessing the need for ECG monitoring based on the QTc risk score; Q5=Question 5: Recommending therapy if the risk score ≤ 7 points; Q6=Question 6: Assessing baseline ECG if risk score ≥ 7 points; Q7=Question 7: If ECG shows QTc ≥ 500 ms, avoid therapy and consider cardiac consultation; Q8=Question 8; If ECG shows QTc ≤ 500 ms, recommend therapy with follow up ECG and physical exam at specified cases.

Figure 4 I-CVI scores for the reliability of references used in the QTc Prolongation Algorithm decision steps.

Notes: Q1=Question 1: Assessing the drug using CredibleMeds^®; Q2=Question 2: Assessing the drug dose, route, and drug interactions; Q3=Question 3: Assessing the risk by calculating the patient’s QTc prolongation score; Q4=Question 4: Assessing the need for ECG monitoring based on the QTc risk score; Q5=Question 5: Recommending therapy if the risk score ≤ 7 points; Q6=Question 6: Assessing baseline ECG if risk score ≥ 7 points; Q7=Question 7: If ECG shows QTc ≥ 500 ms, avoid therapy and consider cardiac consultation; Q8=Question 8; If ECG shows QTc ≤ 500 ms, recommend therapy with follow up ECG and physical exam at specified cases.

Figure 5 Emerging themes from participants’ feedback about the QTcI Prolongation Algorithm decision steps.

Abbreviation: QTcI, corrected QT interval.

Table 2 Management of QTc Prolongation in Patients Receiving Antipsychotic Drugs

QTcI value in miliseconds (ms)	Action	Refer to cardiology
<440 ms (men) or <470 ms (women)	No action required unless abnormal T-wave morphology	Consider cardiac review if in doubt
>440 ms (men) or >470 ms (women)	Consider reducing dose or switching to drug of lower effect	Consider
>500 ms	Stop suspected causative drug(s) and switch to drug with a lower effect	Immediate cardiology review is needed