Visual Analog Scales

The Visual Analog or Analogue Scale (VAS) is designed to present to the respondent a rating scale with minimum constraints. Respondents mark the location on the 10-centimeter line corresponding to the amount of pain they experienced. This gives them the greatest freedom to choose their pain's exact intensity. It also gives the maximum opportunity for each respondent to express a personal response style. VAS data of this type is recorded as the number of millimeters from the left of the line with the range 0-100. The scales consist of 100-point lines anchored with “not at all” on one end and “extremely” on the other. Participants will report at each clinic visit the extent to which they felt any craving for opiates, the severity of their withdrawal symptoms, and the extent to which the study medication has helped to ease the cravings (if applicable). On induction day this measure is to be completed pre dose (screening VAS) and post dose for the induction day VAS.