Prior research supports the validity and short-term test-retest stability of 4 commonly used scales for assessing pain intensity (Visual Analogue Scale [VAS], 6-point Verbal Rating Scale [VRS-6], Numerical Rating Scale [NRS-11], and Face Pain Scale-Revised [FPS-R]). However, the relative stability and ability of these measures to detect changes in pain intensity over longer time periods have not yet been examined. The 4 scales were administered to a Thai cohort of 250 chronic pain outpatients on 2 occasions to assess worst and average pain intensity 6 weeks apart. All 4 scales were found to be valid for detecting decreases in pain, and the VAS, NRS-11, and FPS-R evidenced the most validity for detecting increases in pain. Overall, the NRS-11 emerged as showing the most sensitivity and stability. This study adds to the body of knowledge the stability of pain intensity scales over the longer term.
PainSA is a chapter of the International Association for the Study of Pain. Our mission is to improve all aspects of pain management in Southern Africa.