First study to assess the reliability of commonly used pain scales in children with disorders of gut-brain interaction.

BACKGROUND: There are no validated measures to assess chronic abdominal pain (AP) in clinical trials of children with disorders of gut-brain interaction (DGBIs). Currently used AP measures are extrapolated from studies on adults or children with acute AP. The primary aim of the study was to assess the commonly used pain scales in children with DGBIs. The secondary aim of the study was to compare specific pain measures with the overall subjective assessment of AP well-being in children. METHODS: A sub-study from multicenter crossover randomized controlled trial (RCT) was conducted. Children with AP-DGBIs completed daily diaries for 7 weeks. It included three widely used AP scales: the numeric rating scale (NRS), the visual analog scale (VAS), the Faces Pain Scale Revised (FPS-R), and a global improvement question. Strength of correlations among scales and questions was assessed with the Pearson correlation coefficient (r). KEY RESULTS: Thirty subjects completed the study. Children completed 4975 of 5880 (84.6%) pain and global responses. The VAS and NRS had strongest correlation among them, r = 0.893 (p < 0.001). The FPS-R also demonstrated strong correlations with the VAS r = 0.773 (p < 0.001), NRS = 0.783 (p < 0.001). The three scales exhibited weaker but significant correlations with the global question. Strong correlations were consistent when stratified by age groups. CONCLUSION: This is the first study to assess the most used AP scales in children with DGBIs. It supports the Rome IV recommendations on using the VAS and NRS scales. It also suggests that FPS-R, that was not part of Rome IV, can also be used in RCTs. Congruent with the biopsychosocial model, there was a weaker correlation between AP measures and the global question. This suggests that the global question measures more domains than AP alone and that it should also be incorporated in DGBIs RCTs in children.