Agreement between verbal numerical scale and visual analog scale assessments in monitoring acute postoperative pain

Objective: To determine the agreement between verbal numerical and visual analog scale assessments of acute postoperative pain on 3 consecutive days. Methods: Pain data were recorded for 2 months for sequentially enrolled patients receiving parenteral opioids or neuraxial blocks for analgesia after major surgery in a tertiary level hospital. Each patient was asked to assess pain on the visual analog and verbal numerical scales every 24 hours for 3 consecutive days. Agreement was estimated by the intraclass correlation coefficient and the Spearman correlation coefficient. The results were analyzed in 2 age strata: age 65 years or younger and older than 65 years. Results: Data for 159 patients (105 <= 65 years; 54 > 65 years) were analyzed. The visual analog scale could not be used with 12 patients; all patients were able to assess pain on the verbal numerical scale. The intraclass correlation coefficient was > 0.70 for all 3 days; the highest coefficients were for patients over 65 years of age. Conclusions: Agreement between pain assessments on the visual analog and verbal numerical scales can be considered good or very good on all 3 days, with stronger agreement when the scales are used in patients over the age of 65 years. Cooperation was better for the numerical scale than for the visual analog scale. Scores on the verbal numerical scale were consistently higher than scores on the visual analog scale.