Reliability of the Questionnaire for Verifying Stroke-free Status

Background: The Questionnaire for Verifying Stroke-Free Status (QVSS) is a practical instrument for confirming absence of previous symptomatic stroke or transient ischemic attack in control subjects participating in stroke research.

Methods: We tested reliability of telephone administration of the QVSS in stroke patients and healthy volunteers aged >/=50 years. For intrarater reliability, one interviewer administered the QVSS twice to the same subjects 8 weeks apart (115 subjects). For interrater reliability, one interviewer administered the QVSS and a different interviewer readministered the QVSS 8 weeks later (107 subjects). Both interviewer and interviewee were masked to responses from the first interview.

Results: Intrarater agreement for overall classification of stroke-free status was 0.90 [95% confidence interval (CI), 0.82-0.94], with a kappa of 0.78 (95% CI, 0.67-0.90). Interrater agreement for overall classification was 0.94 (95% CI, 0.88-0.98), with a kappa of 0.89 (95% CI, 0.80-0.97).

Conclusion: The QVSS is a reliable instrument for telephone interviews in stroke research when applied to adult populations without severe deficits of cognition or verbal communication.