DAWN Criteria for Mechanical Thrombectomy
The DAWN criteria use age-adjusted clinical-imaging mismatch to select patients for thrombectomy 6-24 hours after last known well, matching specific NIHSS scores with maximum infarct core volumes based on age thresholds of ≤80 versus >80 years 1, 2.
Specific DAWN Eligibility Criteria
The DAWN trial established three distinct patient groups based on clinical-imaging mismatch 3, 2:
Group A: Age ≥80 years
- NIHSS ≥10
- Infarct core 0-20 cm³
Group B: Age <80 years with moderate deficit
- NIHSS 10-20
- Infarct core 0-30 cm³
Group C: Age <80 years with severe deficit
- NIHSS ≥21
- Infarct core 31-50 cm³
Additional Required Criteria
Beyond the age-NIHSS-core mismatch, patients must have:
- Large vessel occlusion of intracranial internal carotid artery or proximal middle cerebral artery (M1) confirmed on CTA or MRA 3, 2
- Time window: 6-24 hours from last known well 1
- Imaging modality: Core volume measured by CT perfusion or DW-MRI using automated software (RAPID was used in the trial) 3
Critical Implementation Points
The 2018 AHA/ASA Guidelines explicitly state that DAWN or DEFUSE-3 eligibility criteria should be strictly adhered to in clinical practice 1. This is a Class I, Level A recommendation for the 6-16 hour window and Class IIa, Level B-R for the 16-24 hour window 1.
Why Strict Adherence Matters
The guidelines emphasize that DAWN and DEFUSE-3 are the only randomized controlled trials demonstrating benefit beyond 6 hours 1. The DAWN trial showed remarkable outcomes with 49% achieving functional independence (mRS 0-2) versus 13% in controls, with an adjusted difference of 33 percentage points 1, 2.
Common Pitfalls to Avoid
- Do not extrapolate beyond these criteria: While observational data suggests some trial-ineligible patients may benefit 4, the guidelines mandate strict adherence to proven criteria
- Core volume is absolute: A patient age 75 with NIHSS 18 and 35 cm³ core does NOT qualify (exceeds the 30 cm³ limit for that NIHSS range)
- Age cutoff is binary: The 80-year threshold creates distinct eligibility groups with different core volume limits
- Imaging is mandatory: Clinical assessment alone is insufficient; you must have CT perfusion or DW-MRI to measure core volume 1
Practical Algorithm
- Confirm time window: 6-24 hours from last known well
- Obtain vascular imaging: Confirm ICA or M1 occlusion
- Measure infarct core: Use automated software on CTP or DW-MRI
- Apply age-based criteria:
- If age ≥80: Requires NIHSS ≥10 AND core ≤20 cm³
- If age <80 with NIHSS 10-20: Core must be ≤30 cm³
- If age <80 with NIHSS ≥21: Core must be 31-50 cm³
- Proceed to thrombectomy if all criteria met
The DAWN criteria demonstrated 90-day mortality of 19% with thrombectomy versus 18% with medical management, with symptomatic ICH rates of 6% versus 3% (not statistically different) 2, establishing both efficacy and safety in this carefully selected population.