Comparison of four pain scales in children with acute abdominal pain in a pediatric emergency department

Study objective: In children, the agreement between the many scales used to document the intensity of pain is not well known. Thus, to determine the agreement, we evaluate the visual analog scale, the standardized color analog scale, the Wong-Baker FACES Pain Rating Scale, and a verbal numeric scale in children with acute abdominal pain suggestive of appendicitis in a pediatric emergency department (ED). Methods: Participants were children who were aged 8 to 18 years, presented to a pediatric ED with abdominal pain suggestive of appendicitis, and were recruited to participate in a randomized controlled trial evaluating the efficacy of morphine. Patients were initially asked to grade their pain on a plasticized color analog scale, a paper visual analog scale, a paper Wong-Baker FACES Pain Rating Scale, and then with a verbal numeric scale. Thirty minutes after morphine or placebo administration, the assessment was repeated. All scores were then converted to a value of 0 to 100. Agreements between scores were evaluated with the Bland-Altman method, and the 95% lower and upper limits were reported. We defined a priori the maximum limit of agreement at +/- 20 mm. Results: A total of 87 children were included in the study, 58 of them with confirmed appendicitis. The 95% limits of agreement for each pair of scales were visual analog scale/color analog scale -18.6, 14.4; visual analog scale/Wong-Baker FACES Pain Rating Scale -20.1, 33.7; visual analog scale/verbal numeric scale -30.2, 20.7; color analog scale/Wong-Baker FACES Pain Rating Scale -18.5, 36.3; color analog scale/verbal numeric scale -26.9, 22.1; and Wong-Baker FACES Pain Rating Scale/verbal numeric scale -38.7, 15.7. Conclusion: Our study suggests that only the visual analog scale and the color analog scale have acceptable agreement in children with moderate to severe acute abdominal pain. In particular, the verbal numeric scale is not in agreement with the other evaluated scales.