The minimum clinically significant difference in visual analogue scale pain score in a local emergency setting

Abstract

Objectives: To determine whether the minimum clinically significant difference (MCSD) in visual analogue scale (VAS) pain score varies with age, gender, education level and cause of pain (trauma versus non-trauma) in Chinese patients. Methods: This was a prospective descriptive study of local Chinese patients 15 years of age or older who presented with pain to the accident & emergency department. On presentation, patients were asked to indicate their current pain severity with a single mark through a standard 100-mm visual analogue scale. Then they would be offered an analgesic for pain-relief. After 30-45 minutes, the patients were asked to give a verbal categorical rating of their pain as 'a lot better', 'a little better', 'much the same', 'a little worse', or 'much worse' and to mark the level of pain on a VAS of the same type as used previously. The MCSD in VAS pain score was defined as the mean difference between the current and preceding scores when the subject reported 'a little worse' or 'a little better' in pain. Data were compared based on gender, age, education level, and traumatic versus non-traumatic causes of pain. Results: 186 patients were enrolled in the study, yielding 77 evaluable comparisons where pain was rated as 'a little better' or 'a little worse'. Overall, the MCSD in VAS pain score in the group was 17 mm (95%CI 13.6 mm to 20.6 mm). There were statistically significant differences between the MCSD in VAS pain score between genders and causes of pain (trauma versus non-trauma). Conclusions: The MCSD in VAS pain scores was found to be 17 mm. There was significant differences in MCSD in VAS pain score in different genders and between trauma and non-trauma cases.