Visual Analog Scale Rating Change Cut-Offs for Detection of Improvement in Nausea Severity.

OBJECTIVE:To determine accuracy and best cut-point of measured and percentage visual analog scale (VAS) change for detection of symptom improvement.METHODS:A pooled analysis of three previously published studies was conducted. All patients had baseline and 30 min VAS ratings linked to described symptom change. A receiver operating characteristic curve analysis was performed.RESULTS:Area under the curve for detecting symptom improvement was 0.86 (95% CI 0.83-0.90) and 0.87 (95% CI 0.84-0.90) for measured and percentage VAS change. Best cut-points were -8 mm and -20%.CONCLUSION:Accuracy of VAS change for detection of symptom improvement is good to excellent. Use of this outcome measure in future ED antiemetic trials is supported.