Comparing visual-analog and numeric scales for assessing menstrual pain.

Measurements from visual-analog (VAS) and numeric scales were used to assess menstrual pain in a prevalence study of 1,387 women in Madrid, Spain. The data obtained from these 2 scales were compared to determine if significant differences existed between the 2 rating methods. Findings indicated that both scales are useful for assessing menstrual pain. A high degree of correlation was found between the 2 scales; larger rating differences were seen in only a small percentage of the sample. The numeric scale is easier and more convenient to use than the VAS and is recommended in epidemiologic and prevalence studies such as this one.