Clinically Meaningful Reduction in Pain Severity by Using a Unidimensional Scale and Verbal Categorical Rating of Pain

Choi,  Do Il; Jung,  Tae O; Jin,  Young Ho; Lee,  Jae Baek

J Korean Soc Emerg Med > Volume 14(1); 2003 > Article

Original Article

Journal of The Korean Society of Emergency Medicine 2003;14(1): 66-70.

Clinically Meaningful Reduction in Pain Severity by Using a Unidimensional Scale and Verbal Categorical Rating of Pain

Do Il Choi, Tae O Jung, Young Ho Jin, Jae Baek Lee

¹Department of Emergency, Medical School, Chonbuk National University and Hospital, Jeonju, Korea. emjin@moak.chonbuk.ac.kr
²Institute of Medical Science, Medical School, Chonbuk National University and Hospital, Jeonju, Korea.

ABSTRACT

PURPOSE:
The visual analogue scale (VAS) pain score is widely and frequently used to evaluate the severity of pain. However, statistically significant differences in the VAS scores may not always mean differences in pain severity. This study is to determine clinically meaningful reductions in pain severity as measured by the VAS and by a verbal categorical rating of pain.
METHODS:
Three hundred adult patients presenting to the emergency department (ED) with acute pain resulting from trauma or non-traumatic diseases were enrolled in this prospective, descriptive study. A 100-mm non-hatched, horizontal visual analogue scale was used to measure pain severity. The VAS measurements were obtained two times 1 minute apart at admission, 30 minutes after admission, and 1 hour after treatment. At each VAS measurements, patients also gave verbal ratings of their pain as "more pain,""the same pain," or "less pain." Data from the groups reporting "the same pain" or "less pain" were compared with their preceding descriptions and yielded a VAS difference. The mean VAS change was calculated, from which a grand means and 95% confidence intervals (95% CI) were determined.
RESULTS:
At 30 minutes after admission and 1 hour after treatment, 256 and 31 patients, respectively described their pain as "the same pain,"and 33 and 269 patients described it as "less pain." The mean reduction in VAS for the group reporting that pain was "the same pain" was 13 to 16 mm (95% CI, 8 to 20 mm) instead of 'zero.'For the group reporting that pain was "less pain," the mean reductions in VAS score were 24 mm (95% CI, 20 to 28 mm) at 30 minutes after admission and 44 mm (95% CI, 42 to 46 mm) at 1 hour after treatment.
CONCLUSION:
When evaluating management for acute pain in the ED, a difference in VAS score of less than 20 mm without regard to the presence or absence of treatment is unlikely to signify a clinically meaningful reduction in pain severity. This study provides guidance to those who design and interpret clinical studies of the acute pain experience in the ED.

Key words: Acute pain, Pain management, Visual analogue scale, Verbal categorical rating