ADD-RS + D-dimer Calculator

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ADD-RS Score	D-dimer (ng/mL)	Interpretation / Risk	Recommended Action
0	<500	Very low risk	AAS can often be safely ruled out without imaging (ADvISED protocol)
0	≥500	Low risk but positive D-dimer	Imaging recommended to exclude AAS
1	<500	Low-intermediate risk	Clinical judgment; consider imaging if suspicion persists
1	≥500	Intermediate risk	Imaging (CTA) recommended
2–3	<500	High risk	Imaging strongly recommended regardless of D-dimer
2–3	≥500	Very high risk	Immediate imaging (CTA) and urgent management

linical Notes / Key Points

1. ADD-RS 0 + D-dimer <500 ng/mL → Safely rules out acute aortic syndrome (AAS) in early presenters.
2. ADD-RS 0 but D-dimer ≥500 ng/mL → Even with low ADD-RS, elevated D-dimer warrants imaging.
3. ADD-RS ≥2 → High pretest probability: imaging is indicated even if D-dimer is normal, because false negatives occur in high-risk patients.
4. D-dimer limitations:
   • Sensitivity decreases >24 hours from symptom onset.
   • Less reliable in chronic dissection or delayed presentation.
5. Clinical integration: Always combine ADD-RS + D-dimer with clinical judgment, vital signs, and exam findings.

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Example Interpretations

Case 1:

• ADD-RS = 0, D-dimer = 400 ng/mL → Very low risk → No CTA needed if early presentation and low clinical suspicion.

Case 2:

• ADD-RS = 1, D-dimer = 700 ng/mL → Intermediate risk → CTA recommended to rule out AAS.

Case 3:

• ADD-RS = 2, D-dimer = 300 ng/mL → High risk → CTA required despite normal D-dimer.

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