Establishing clinical significance thresholds for common pediatric pain-related patient-reported outcome measures

ABSTRACT: Pediatric patient-reported outcome measures (PROMs) are essential in pain intervention research, yet their changes often lack clear clinical significance. The authors estimated minimally important differences (MIDs) for commonly used and freely available PROMs in pediatric pain intervention research. Using data from a longitudinal multicenter study (N = 453) on children and adolescents aged 8 to 17 years with chronic pain in Germany, the authors applied equipercentile linking to align pre-post intervention changes in PROMs with global ratings of change. The MID for improvement in the Functional Disability Inventory (FDI) is 4.96 points (8.27% of the instrument range, Hedges g = 0.47). In the Revised Children's Anxiety and Depression Scale (RCADS), the MID for anxiety is 3.32 points (2.99% of subscale range, g = 0.17) and 1.38 points (4.60%, g = 0.24) for depression. A reduction of 0.64 points (g = 0.32) on an 11-point pain intensity scale indicates meaningful improvement. For pain self-efficacy (Scale for Pain Self-Efficacy), an increase of 3.72 points (8.46% of instrument range, g = 0.44) constitutes an MID. This is the first study to estimate detailed anchor-based thresholds using equipercentile linking for widely used pediatric PROMs based on patient perspectives, distinguishing clinical from statistical significance. Although primarily applicable to pediatric chronic pain, these patient-centered thresholds may extend to broader pediatric populations.