4Ts Score for Heparin-Induced Thrombocytopenia: Clinical Guide

Overview

Estimates pre-test probability of immune heparin-induced thrombocytopenia.

Clinical Significance

Scores 0–3 are low, 4–5 intermediate and 6–8 high pre-test probability.

When to Use

• Use as structured clinical decision support when the required data are available and reliable.

How It Is Calculated

• The displayed variables are combined using the published equation, decision rule or weighted point system.

Interpretation

• Scores 0–3 are low, 4–5 intermediate and 6–8 high pre-test probability.

Worked Example

Enter verified patient data in the displayed units; MedicalC applies the published model.

Limitations

• Risk and classification tools can be misapplied outside their validated population.
• Missing, estimated or non-contemporaneous data may materially change the result.

Clinical Pearls

• Document the inputs, units, date and clinical setting with the result.
• Use serial scores only when the same instrument and measurement method are used consistently.

Common Mistakes

• Using the tool without confirming entry criteria.
• Using approximate or incorrectly converted values.
• Treating a prognostic score as a standalone treatment decision.

References

1. Lo GK et al. J Thromb Haemost. 2006;4:759-765. — Primary or supporting reference for the implemented model.