The Functional Disability Inventory (FDI) is a well-established and commonly used measure of physical functioning and disability in youth with chronic pain. Further validation of the measure has been called for, in particular, examination of the clinical utility and factor structure of the measure. To address this need, we utilized a large multicenter dataset of pediatric patients with chronic pain who had completed the FDI and other measures assessing pain and emotional functioning. Clinical reference points to allow for interpretation of raw scores were developed to enhance clinical utility of the measure and exploratory factor analysis was performed to examine its factor structure. Participants included 1300 youth ages 8 to 18 years (M=14.2 years; 76% female) with chronic pain. Examination of the distribution of FDI scores and validation with measures of depressive symptoms and pain intensity yielded three distinct categories of disability: No/Minimal Disability, Moderate Disability and Severe Disability. Factor analysis of FDI scores revealed a two-factor solution representing vigorous Physical Activities and non-physically strenuous Daily Activities. The three-level classification system and factor structure were further explored via comparison across the four most commonly encountered pain conditions in clinical settings (head, back, abdominal and widespread pain). Our findings provide important new information regarding the clinical utility and validity of the FDI. This will greatly enhance the interpretability of scores for research and clinical use in a wide range of pediatric pain conditions. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Conflict of InterestThe authors have no financial or other relationship that might lead to a conflict of interest. NIH Public Access Author ManuscriptPain. Author manuscript; available in PMC 2012 July 1. In particular these findings will facilitate use of the FDI as an outcome measure in future clinical trials.Assessment of pain-related disability is an essential component in the evaluation and treatment of pediatric patients with chronic pain. The Functional Disability Inventory (FDI) [40] is one of the most widely used measures of functional impairment among children and adolescents with chronic pain, and its initial psychometric properties have been well established [3,26]. The FDI is a brief 15-item instrument originally developed to assess disability in children and adolescents with chronic abdominal pain [41,3]. Subsequently it has been used with a variety of pediatric chronic pain conditions such as fibromyalgi...

IMPORTANCE Early, safe, effective, and durable evidence-based interventions for children and adolescents with chronic migraine do not exist.OBJECTIVE To determine the benefits of cognitive behavioral therapy (CBT) when combined with amitriptyline vs headache education plus amitriptyline. DESIGN, SETTING, AND PARTICIPANTSA randomized clinical trial of 135 youth (79% female) aged 10 to 17 years diagnosed with chronic migraine (Ն15 days with headache/month) and a Pediatric Migraine Disability Assessment Score (PedMIDAS) greater than 20 points were assigned to the CBT plus amitriptyline group (n = 64) or the headache education plus amitriptyline group (n = 71). The study was conducted in the Headache Center at Cincinnati Children's Hospital between October 2006 and September 2012; 129 completed 20-week follow-up and 124 completed 12-month follow-up.INTERVENTIONS Ten CBT vs 10 headache education sessions involving equivalent time and therapist attention. Each group received 1 mg/kg/d of amitriptyline and a 20-week end point visit. In addition, follow-up visits were conducted at 3, 6, 9, and 12 months. MAIN OUTCOMES AND MEASURESThe primary end point was days with headache and the secondary end point was PedMIDAS (disability score range: 0-240 points; 0-10 for little to none, 11-30 for mild, 31-50 for moderate, >50 for severe); both end points were determined at 20 weeks. Durability was examined over the 12-month follow-up period. Clinical significance was measured by a 50% or greater reduction in days with headache and a disability score in the mild to none range (<20 points).RESULTS At baseline, there were a mean (SD) of 21 (5) days with headache per 28 days and the mean (SD) PedMIDAS was 68 (32) points. At the 20-week end point, days with headache were reduced by 11.5 for the CBT plus amitriptyline group vs 6.8 for the headache education plus amitriptyline group (difference, 4.7 [95% CI, 1.7-7.7] days; P = .002). The PedMIDAS decreased by 52.7 points for the CBT group vs 38.6 points for the headache education group (difference, 14.1 [95% CI, 3.3-24.9] points; P = .01). In the CBT group, 66% had a 50% or greater reduction in headache days vs 36% in the headache education group (odds ratio, 3.5 [95% CI, 1.7-7.2]; P < .001). At 12-month follow-up, 86% of the CBT group had a 50% or greater reduction in headache days vs 69% of the headache education group; 88% of the CBT group had a PedMIDAS of less than 20 points vs 76% of the headache education group. Measured treatment credibility and integrity was high for both groups.CONCLUSIONS AND RELEVANCE Among young persons with chronic migraine, the use of CBT plus amitriptyline resulted in greater reductions in days with headache and migraine-related disability compared with use of headache education plus amitriptyline. These findings support the efficacy of CBT in the treatment of chronic migraine in children and adolescents.