Assessment Of Postoperative Pain Intensity In Chinese Patients

Objectives: The purposes of the study were to determine the psychometric properties and usability of four commonly used pain scales for the assessment of postoperative pain intensity in Chinese patients, and to provide reliable data for the selection of the right tools to assess pain intensity.Subjects: From Sep 2002 to Jan 2003, one hundred and seventy-three patients undergoing scheduled surgery in a general hospital in Guangzhou participated in the study (age range 18-78 years, mean age 45.3 ?15.0 years).Methods: Patients were tested preoperatively with four scales (Visual Analog Scale, VAS; Numeric Rating Scale, NRS; Verbal Descriptor Scale, VDS; and Faces Pain Scale Revised, FPS-R) to rate their remembered pain and expected postoperative pain. After operation, patients were interviewed in the evening (18:00 to 21:00) from the operative day (day 0) to the 6th postoperative day (day 6) to record their current pain intensity scores and retrospective ratings of worst, least and average pain levels on that day. On day 6, retrospective ratings over the 7 days were also obtained and the situation of pain relief and tool preference were investigated. Results: All the four scales showed good reliability and validity with the ICCs above 0.83, the correlation between ratings of each scales was statistically significant, but the correlation between the FPS-R and VDS appeared least significant. The correlation between current and average pain was stronger than that between the worstand the least pain. All the four scales were sensitive for testing the efficacy of analgesic interventions. Although there was a significant decrease in scores with time on all scales, differences in scores were significant within day 3, between day 0 to day 2 and day 4 to day 6. FPS-R had higher pain scores, being the most sensitive scale for assessing current, least and average pain, while VAS was the least sensitive. When measuring the worst pain, YDS was the most sensitive and NRS the least sensitive. In addition, the error rate for the first time use of the scales to assess remembered pain was VAS 12.3%, NRS 4.9%, FPS-R 2.5% and YDS 0.8%, respectively. When used to assess the expected postoperative pain and actual postoperative pain, the error rates for each tool remained rather low. The tool preference was FPS-R 48.1%, NRS 24.4%, YDS 23.1% and VAS 3.8%, respectively.Conclusions: The findings confirm the importance of ongoing assessment and effective management of postoperative pain and that all the four scales can be used for Chinese adults to report pain intensity, but FPS-R emerges as the best scale with respect to reliability, validity, error and preference rate. A mini pain assessment ruler that incorporates a FPS-R, NRS and YDS would be the most appropriate tool for clinical use.