Comparative study of verbal rating scale and numerical rating scale to assess postoperative pain intensity in the post anesthesia care unit: A prospective observational cohort study

Postsurgical patients usually have difficulty in answering the self-report pain scales due to the residual effects of anesthetic or sedative agents in the post-anesthesia care unit (PACU). A comparative analysis of pain assessment tools used in the PACU is lacking. In this prospective observational study, we compared the intensity of pain using the 11-point numeric rating scale (NRS) and the 4-category verbal rating scale (VRS) thrice, 5 minutes after PACU admission, 20 minutes after the first assessment, and just before discharge from the PACU in 200 patients undergone surgery. Spearman rank correlation analysis was used to investigate the correlation between 2 scales, and the weighted kappa (κ) coefficient was performed to evaluate inter-scale reliability. Response rates of the 2 scales were also compared. VRS and NRS were highly correlated during all 3 comparisons (r = 0.767, 0.714, and 0.653, respectively; P < .0001). Each category of VRS showed a statistically significant difference in pain intensity measured by NRS during all 3 assessments. Inter-scale reliability had a fair strength of agreement for all 3 measurements (weighted κ = 0.519, 95% CI: 0.421–0.618; weighted κ = 0.511, 95% C.I: 0.409–0.613; weighted κ = 0.452, 95% C.I: 0.352–0.551, respectively). VRS showed a higher response rate for PACU patients compared to NRS in all 3 measurements (96% vs 77.5%, 99% vs 81.5%, and 96.5% vs 86.5%, respectively; P < .0001). In the PACU, VRS is a reasonable and practical pain intensity measurement tool for postsurgical patients, considering the high correlation between VRS and NRS, and a higher response rate.