This review examines how guideline-determining thrombectomy trials outline the assessment of pre-stroke disability, highlighting the potential for errors and suggesting strategies for improvement.

Current acute ischemic stroke guidelines do not recommend mechanical thrombectomy (MT) for patients with prior disabilities, estimated around 30% of patients. Although the Modified Rankin Scale (mRS) is validated for post-stroke assessment, it is often applied to evaluate pre-stroke disability with minimal evidence or implementation guidance to support this application. 

We reviewed the full manuscripts, supplementary appendices and protocols of five stroke thrombectomy trials that were referenced in the 2019 American Heart Association Guidelines EXTENDA-IA, SWIFT-PRIME, REVASCAT, DAWN, DEFUSE-3 and three “large core” trials,  ANGEL-ASPECT, SELECT-2, and RESCUE-LIMIT.

We assessed whether trials assigned individuals to evaluate pre-stroke mRS scores, required training for those evaluators, utilized structured interviews, recognized acceptable patient-proxy relationships for reporting disability history, and addressed patient-provider language barriers.

All trials except DAWN, SELECT-2, and ANGEL-ASPECT designated specific personnel for determining the mRS. All eight trials required mRS training before participation. No trials mentioned use of structured versus unstructured interviews, available translators, or how to vet interview proxies.

The study highlights that most practice influencing stroke thrombectomy trials offered limited guidance on assessing pre-stroke disability. To improve future interrater reliability, mRS training should focus on disability assessment in acute settings, utilizing structured interviews, and the interview of patient proxies. Additionally, combining objective imaging characteristics indicative of low recovery potential in conjunction with the mRS may enhance the reliability of disability assessments.