Assessing the Minimal Clinically Important Difference and Patient-Accepted Symptom State Using Visual Analog Scales and Numerical Rating Scales in Postoperative Patients: a Prospective Descriptive Study

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Fa-ngam Charoenpol
Atipong Pathanasethpong
Piyakorn Ouypron
Yuwadee Huntula
Nathee Maneewan
Arissa Tamwong
Wannisa Suphokam


Introduction: Visual analog scale (VAS) and numerical rating scale (NRS) are widely used in measuring pain scores and guide treatment. In using these tools, the minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) are crucial for guiding treatment. However, they vary in different situations and populations. The aim of the present study was to determine MCID and PASS for acute pain in elective surgical patients. Materials and methods: Pain assessment was done by first measuring VAS and NRS in the immediate postoperative period. Then 24 hours later, participants were asked to rate their pain score, perception of pain change, and state of recovery. The mean changes in pain scores among patients who reported “a little change” were used to calculate MCID. The 75th percentile of pain score rated by participants who considered themselves as having recovered well from surgery was defined as PASS. Results: Data from 79 of 104 participants, after excluding illogical data, showed that the MCID was 16 mm for VAS and 1.8 for NRS. While PASS for VAS and NRS were 38 mm and 5, respectively. Conclusion: MCID and PASS in our setting were similar to other population.

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