Predictive Value of Emergency Physician-coded Cincinnati Prehospital Stroke Scale Scores Based on Witness Reports and Their Association With Action Decision Time: A Cross-sectional Emergency Department Validation Study

The Cincinnati Prehospital Stroke Scale (CPSS) is traditionally scored directly by a healthcare professional or a layperson who independently observes facial droop, arm weakness, and speech disturbance, constituting the primary CPSS score. In contrast, this study focuses on witness-derived secondary CPSS scoring, which is performed indirectly by an emergency physician who is blinded to the patient's physical examination findings and relies exclusively on symptom descriptions provided by witnesses of the patient's initial presentation.

This prospective analytical cross-sectional study aims to evaluate the predictive accuracy of secondary CPSS scores obtained by emergency physicians through structured interviews with witnesses of suspected stroke cases. Interrater reliability will be assessed between secondary CPSS scores independently assigned by a senior emergency medicine resident and an attending emergency physician based on witness-reported symptom descriptions. Secondary CPSS scores will then be compared with final neuroimaging diagnoses (CT/MRI), which will serve as the diagnostic gold standard. The study will also investigate the association between physician-coded secondary CPSS scores, witness demographic characteristics, and delays in seeking emergency medical care.

Research Questions

1. Are witness-derived secondary CPSS scores, as assigned by an emergency physician, a valid tool for predicting ischemic stroke?
2. Are witness-derived secondary CPSS scores of ≥1 associated with shorter recognition-to-action time (decision delay)?

Research Hypotheses

1. Witness-derived secondary CPSS scores assigned by an emergency physician are a valid diagnostic tool for predicting ischemic stroke.
2. Witness-derived secondary CPSS scores of ≥1 are associated with shorter recognition-to-action time.

A total of 235 stroke witnesses, including family members, friends, neighbors, or bystanders who observed the patient's initial symptoms and accompanied the patient to the emergency department with acute stroke or stroke-like symptoms, will be included. All eligible participants will provide written informed consent prior to enrollment. Witnesses will undergo a structured, physician-administered interview in which they will be asked to recall and describe the patient's first symptoms. Based solely on these reports, an emergency physician blinded to the patient's clinical examination will assign a secondary CPSS score focusing on facial droop, arm weakness, and speech impairment. Two investigators will independently score the secondary CPSS to enable interrater agreement analysis.

Participants will also provide demographic data and report three key time points: symptom recognition, decision to seek care, and arrival at the emergency department. These data will be used to calculate onset-to-door time (prehospital delay), recognition-to-action time (decision delay), and call-to-door time (transfer delay). Data collection and emergency care provision will be conducted by investigators independent of those performing secondary CPSS scoring to minimize bias.