Determining validity, discriminant ability, responsiveness, and minimal clinically important differences for PROMIS in adult spinal deformity

OBJECTIVE The aim of this study was to determine the concurrent validity, discriminant ability, and responsiveness of the Patient-Reported Outcomes Measurement Information System (PROMIS) in adult spinal deformity (ASD) and to calculate minimal clinically important differences (MCIDs) for PROMIS scores. METHODS The authors used data obtained in 186 surgical patients with ASD. Concurrent validity was determined through correlations between preoperative PROMIS scores and legacy measure scores. PROMIS discriminant ability between disease severity groups was determined using the preoperative Oswestry Disability Index (ODI) value as the anchor. Responsiveness was determined through distribution- and anchor-based methods, using preoperative to postoperative changes in PROMIS scores. MCIDs were estimated on the basis of the responsiveness analysis. RESULTS The authors found strong correlations between PROMIS Pain Interference and ODI and the Scoliosis Research Society 22-item questionnaire Pain component; PROMIS Physical Function and ODI; PROMIS Anxiety and Depression domains and the 12-Item Short Form Health Survey version 2, Physical and Mental Components, Scoliosis Research Society 22-item questionnaire Mental Health component (anxiety only), 9-Item Patient Health Questionnaire (anxiety only), and 7-Item Generalized Anxiety Disorder questionnaire; PROMIS Fatigue and 9-Item Patient Health Questionnaire; and PROMIS Satisfaction with Participation in Social Roles (i.e., Social Satisfaction) and ODI. PROMIS discriminated between disease severity groups in all domains except between none/mild and moderate Anxiety, with mean differences ranging from 3.7 to 8.4 points. PROMIS showed strong responsiveness in Pain Interference; moderate responsiveness in Physical Function and Social Satisfaction; and low responsiveness in Anxiety, Depression, Fatigue, and Sleep Disturbance. Final PROMIS MCIDs were as follows: -6.3 for Anxiety, -4.4 for Depression, -4.6 for Fatigue, -5.0 for Pain Interference, 4.2 for Physical Function, 5.7 for Social Satisfaction, and -3.5 for Sleep Disturbance. CONCLUSIONS PROMIS is a valid assessment of patient health, can discriminate between disease severity levels, and shows responsiveness to changes after ASD surgery. The MCIDs provided herein may help clinicians interpret postoperative changes in PROMIS scores, taking into account the fact that they are pending external validation.