Clinical standard · QT risk
Tisdale QT risk score
What it measures
The score is not a measurement; it is a risk classification. The measured QTc (Fridericia-corrected, ms) is one of its inputs. The two are therefore written separately: "QTc 485 ms · Tisdale 11: high risk".
Risk factors and points
| Factor | Points |
|---|---|
| Age ≥68 years | +1 |
| Female sex | +1 |
| Loop diuretic | +1 |
| Serum potassium ≤3.5 mEq/L | +2 |
| Admission QTc ≥450 ms | +2 |
| Acute myocardial infarction | +2 |
| ≥2 QTc-prolonging drugs | +3 |
| Sepsis | +3 |
| Heart failure | +3 |
| One QTc-prolonging drug | +3 |
| Maximum total | 21 |
The "≥2 QTc-prolonging drugs" row is added on top of the "one QTc-prolonging drug" points: 6 points in total for two drugs.
Risk categories
| Category | Score range |
|---|---|
| Low risk | 0–6 |
| Moderate risk | 7–10 |
| High risk | ≥11 |
What PharmaDeux does with these thresholds
The rule engine recalculates the score on every order and shows which factor each point comes from. The suggestions below are example rule behaviour; they are set to the institution's clinical policy, and the physician makes the final decision.
| ≥11 | ECG monitoring and a non-QT-prolonging alternative should be considered. |
| 7–10 | ECG monitoring and an electrolyte check are advised. |
| ≤6 | No extra QT measure needed; routine monitoring continues. |
To try the score on an example patient, open the QT risk simulator.
Limits
The score was developed and validated in hospitalised adults; the same thresholds have not been shown to hold for outpatients or children. A "QTc-prolonging drug" is one whose product information lists QT prolongation.
References
- 1Tisdale JE, Jaynes HA, Kingery JR, et al. Development and validation of a risk score to predict QT interval prolongation in hospitalized patients. Circ Cardiovasc Qual Outcomes. 2013;6(4):479–487.
- 2Fridericia LS. Die Systolendauer im Elektrokardiogramm bei normalen Menschen und bei Herzkranken. Acta Med Scand. 1920;53:469–486.
This page is for information only and is not for clinical decisions. Decisions rest on the product information (SmPC/PIL), current guidelines and the physician's judgement. Last updated: 13 October 2026