Comparison of Visual Analogue Scale, Categorical Scale and Satisfaction for Postoperative Pain

수술 후 통증 평가를 위한 Visual Analogue Scale, Categorical Scale 그리고 환자 만족도와의 비교

Background: The categorical scales and visual analogue scales (VAS) are methods used for evaluating variations of postoperative pain intensity. Several studies have introduced the idea that there is a clear correlation between visual scales and categorical scales. However, when VAS is the only pain measure in the study, we do not know what point on the VAS represents a category on the categorical scale and their degree of correlation with satisfaction for postoperative pain. Methods: 252 patients who had undergone elective surgery were studied. A 5-point categorical scale (none, mild, moderate, severe, worst possible pain), a 0-100 mm VAS (no pain to worst possible pain) and patient satisfaction score were checked 24 hours after surgery using a pain questionnaire and VAS tool. Results: The mean VAS score of the 14 patients reporting 'no-pain' was $1.9{\pm}0.9$, $23.9{\pm}1.0$ for the 132 patients reporting 'mild-pain', $47.2{\pm}1.1$ for the 82 patients reporting 'moderate-pain' and $67.5{\pm}2.8$ for the 24 patients reporting 'severe-pain'. Of the patients reporting moderate pain, 85% scored over 45.6 mm on the corresponding VAS, with a mean score 47.2 mm. The mean satisfaction scores were $90.6{\pm}2.7$ for the 'no pain', patients, $75.1{\pm}1.3$ for ‘mild pain', $58.3{\pm}1.5$ for 'moderate pain', and $55.1{\pm}4.0$ for 'severe pain' patients. The categorical scale was significantly correlated with VAS (P < 0.01). The satisfaction score was significantly inversely correlated with VAS (P < 0.01). Conclusions: Our results indicate that if a patient records a VAS score in excess of 45.6 mm they would probably have recorded at least moderate pain on a 5-point categorical scale. The categorical scale can be used properly for postoperative pain measurement with VAS. More research is required for the development of suitable pain descriptor for a categorical scale and pain questionnaire in Korean.