Correlations between Numerical Rating Scale and Visual Analog Scale Pain Scores in the Assessment of Postoperative Pain

Abstract

Background: We wondered what type of pain scores is more available and rliable during the immediate postoperative period. In this study, we compared a numerical rating scale (NRS) with a visual analog scale (VAS) pain scores to assess postoperative pain. Methods: Fifty patients were educated as to how to describe pain intensity using the NRS (11-point) and VAS (10 cm) scores during the evening before elective laparoscopic cholecystectomy. Following their operation, patents checked their pain intensity using NRS and VAS at postoperative 1 hour in the recovery room with the assistance of an anesthesiologist, and 3, 6, 12, 18 and 24 h by themselves. The absolute values of the NRS and VAS scores were analyzed for inter-individual variability and for correlations between the two. Results: Forty-eight patients finished this study. The absolute value of the mean NRS score was slightly higher than that of the mean VAS score at each time point. However, the mean difference was only 0.4. Overall, the two parameters correlated well at each of the six measurement times. The correlation coefficients between the absolute values of the NRS and VAS pain scores for all measurement times were over 0.95. Conclusions: This data suggests that NRS and VAS pain scores are well correlated, and that they are equally useful at assessing immediate postoperative pain. (Korean J Anesthesiol 2003; 45: 238- 243)