Construct Validity of Pediatric PROMIS Computerized Adaptive Testing Measures in Children with Adolescent Idiopathic Scoliosis

Background: The use of patient-reported outcome measures, especially Patient-Reported Outcomes Measurement Information System (PROMIS) measures, has increased in recent years. Given this growth, it is imperative to ensure that the measures being used are validated for the intended population(s)/disease(s). Our objective was to assess the construct validity of 8 PROMIS computer adaptive testing (CAT) measures among children with adolescent idiopathic scoliosis (AIS). Methods: We prospectively enrolled 200 children (aged 10 to 17 y) with AIS, who completed 8 PROMIS CATs (Anxiety, Depressive Symptoms, Mobility, Pain Behavior, Pain Interference, Peer Relationships, Physical Activity, Physical Stress Experiences) and the Scoliosis Research Society-22r questionnaire (SRS-22r) electronically. Treatment categories were observation, bracing, indicated for surgery, or postoperative from posterior spinal fusion. Construct validity was evaluated using known group analysis and convergent and discriminant validity analyses. Analysis of variance was used to identify differences in PROMIS T-scores by treatment category (known groups). The Spearman rank correlation coefficient (r s) was calculated between corresponding PROMIS and SRS-22r domains (convergent) and between unrelated PROMIS domains (discriminant). Floor/ceiling effects were calculated. Results: Among treatment categories, significant differences were found in PROMIS Mobility, Pain Behavior, Pain Interference, and Physical Stress Experiences and in all SRS-22r domains (P<0.05) except Mental Health (P=0.15). SRS-22r Pain was strongly correlated with PROMIS Pain Interference (r s=-0.72) and Pain Behavior (r s=-0.71) and moderately correlated with Physical Stress Experiences (r s=-0.57). SRS-22r Mental Health was strongly correlated with PROMIS Depressive Symptoms (r s=-0.72) and moderately correlated with Anxiety (r s=-0.62). SRS-22r Function was moderately correlated with PROMIS Mobility (r s=0.64) and weakly correlated with Physical Activity (r s=0.34). SRS-22r Self-Image was weakly correlated with PROMIS Peer Relationships (r s=0.33). All unrelated PROMIS CATs were weakly correlated (|r s|<0.40). PROMIS Anxiety, Mobility, Pain Behavior, and Pain Interference and SRS-22r Function, Pain, and Satisfaction displayed ceiling effects. Conclusions: Evidence supports the construct validity of 6 PROMIS CATs in evaluating AIS patients. Ceiling effects should be considered when using specific PROMIS CATs. Level of Evidence: Level II, prognostic.