Pain measurement: Visual Analogue Scale (VAS) and Verbal Rating Scale (VRS) in clinical trials with OTC analgesics in headache

Aim: The aim was to assess the performance of the Visual Analogue Scale (VAS) in patients recruited in a clinical trial with over the counter analgesics in headache.Methods: The Thomapyrin Study showed the significant superiority of the fixed combination of acetylsalicylic acid + paracetamol + caffeine over the combination without caffeine, the single preparations, and placebo in the treatment of headache. Patients enrolled into the study were trained in the handling of the VAS by naming categories of a 6-point Verbal Rating Scale (VRS). These data were used to evaluate the level of order consistency between the VAS and VRS, to deduce cut-off points for rescaling the continuous VAS into a discrete ordinal scale using the receiver operating characteristic methodology, and to assess the test-retest performance.Results: Approximately 75% of the patients recorded the pain intensity on the VAS in the same order as given on the VRS. However, in 12.6% of patients, the German terms ‘leicht’ (mild) and ‘masig’ (mo...