The Pediatric Evaluation of Disability Inventory (PEDI)1 is one of the most widely-used measures of children's function world-wide. Originally published in 1992, the PEDI was the first pediatric measure to assess children's functional ability rather than developmental skills. The PEDI is used by physical therapists and other rehabilitation professionals to measure children's self-care, mobility and social function. Increasing its appeal as a clinical assessment is the wealth of published research confirming the PEDI as a valid, reliable and responsive assessment.2-4 The PEDI has been translated into multiple languages and validated for multiple cultures, requires minimal training and is available at a low cost. 5
The original PEDI1 does, however, have limitations.With a total of more than 200 items in the three Functional Skill scale domains, it is time-consuming to administer. In addition, the PEDI's normative scores cover a small age range (six months - 7.5 years) and the content is narrow with most skills at the low end of the functional continuum. In an effort to still measure functional abilities yet improve efficiency and minimize clinician and client burden, a computerized adaptive test version (CAT) of the PEDI has been developed. The Pediatric Evaluation of Disability Inventory Computerized Adaptive Test (PEDI-CAT) represents a major advancement in the assessment of disability in children and youth.5
Computer adaptive testing is not just a computer version of a paper-pencil assessment. Computer adaptive tests (CATs) draw from an extensive bank of items to customize assessments to the unique ability of each examinee.6 Completed using pre-installed software on a computer or iPad, the PEDI-CAT uses a statistical algorithm that selects questions from the PEDI-CAT's large set of items, based on the respondent's previous choices. All respondents begin each domain with the same item from the middle of the range of difficulty and the response to that item then dictates which item will appear next (a harder or easier item), thus tailoring the items to the child and avoiding irrelevant items. As a response is recorded with each subsequent item, the score is re-estimated along with a unique confidence interval and the computer algorithm determines whether the program's stopping rules have been satisfied. If satisfied, the assessment ends. If not satisfied, new items are administered until the stopping rule(s) are satisfied.7
The PEDI-CAT fundamentally mimics what an experienced clinician would do during an assessment. The computer algorithm chooses which items are most appropriate according to a child's ability level and minimizes the number of items needed to insure an accurate score. To illustrate this, consider that a parent indicates that it is "Easy" for their child to walk up one flight of stairs without the use of a handrail.
With a CAT, a question about walking upstairs with a handrail would not be asked as the computer-based algorithm would account for walking up stairs without a handrail being a higher functional skill than walking upstairs using a handrail. This approach minimizes the number of items administered but still allows the clinician to obtain an estimate of a child's functional abilities in a particular area.
Features of the PEDI-CAT
The PEDI-CAT is intended for use with children from birth through 20 years of age and can be used across all diagnoses, conditions and settings.8 As with the original paper-pencil PEDI,1 the PEDI-CAT can be administered by professional judgment of rehabilitation clinicians who are familiar with the child or by parent report.8
The PEDI-CAT measures level of difficulty (Easy, A Little Hard, Hard, Unable) in the three functional domains of Daily Activities, Mobility and Social/Cognitive. The fourth domain, the Responsibility Domain, assesses the extent to which a young person is managing life tasks that enable independent living with responses ranging from "Adult/caregiver has full responsibility, the child does not take any responsibility" to "Child takes full responsibility without any direction, supervision or guidance from an adult/caregiver." Responsibility items require children to use several functional skills in combination to carry out life tasks and are thus believed best for children older than three years of age.
Each of the four PEDI-CAT domains has designated content areas (See Table), is self-contained and can be used separately or with the other domains. For all domains, age, gender and mobility device filters prevent irrelevant items from being presented. In addition, item wording uses everyday language and gives clear examples to enhance the respondent's understanding of the item's meaning. Illustrations of the Daily Activities and Mobility items are also included to facilitate the respondent's understanding of the item's intent.8
There are currently two versions of the PEDI-CAT. The Speedy ("Precision") CAT is the most efficient CAT as it is the quickest way to get a precise score estimate while administering up to 15 items per domain. In the Content-Balanced ("Comprehensive") CAT, approximately 30 items per domain are administered for a score to be generated, which includes a balance of items from each of the content areas within each domain. The Comprehensive CAT is most useful when the CAT is administered for individual program planning.8
The PEDI-CAT does not require any special environment, materials or activities to administer other than the computerized assessment itself. Typical performance at the present time is assessed. The PEDI-CAT can be completed on multiple occasions for the same child (e.g., admission, discharge, follow-up) and there is no minimum time that must pass between assessments.8
The PEDI-CAT provides normative standard scores for 21 age groups. Normative standard scores are provided as age percentiles and T scores and can be used to interpret a child's functioning relative to others of the same age. Scaled scores are also available for all ages and provide an indication of the child's current level of function. Score reports are generated by the PEDI-CAT software and are available immediately at the end of the assessment. PEDI-CAT scores are stored in a database on a local computer or server which allow for review of assessments for patient documentation and monitoring of progress as well as program evaluation. A review of the PEDI-CAT Manual prior to administration and scoring is essential for professionals to familiarize themselves with the administration procedures, instrument content, item intent, response scales and score interpretation.8
Linking Original PEDI Scores to New PEDI-CAT Scores
For clinicians who have used the PEDI 1 but would like to transition to the PEDI-CAT, equations have been developed to link previous Functional Skill Self-care, Mobility and Social Function scores from the original PEDI to the PEDI-CAT so that individual child progress can continue to be tracked. There is no conversion for the Caregiver Assistance Scale as it has been replaced with the Responsibility domain.8
Promise of CATs
CAT-based instruments have the advantage of reducing test burden while increasing test precision because test items are selected to match the patient's ability level, thereby minimizing the number of irrelevant test items administered. CATs are being used for outcome assessment for adults with spinal cord injury,9 arthritis10 and cardiopulmonary conditions.11 For children, the PEDI-CAT is an ideal measure for identifying challenges with activities that limit a child's everyday activities, developing individual child/family goals and examining functional outcomes over a period of time for individual children and for programs.8 In initial research, the PEDI-CAT has been shown to have good content,12,13 concurrent,14 construct12-14 and discriminant15 validity as well as excellent reliability.14,15
For more information about the PEDI-CAT, visit CRECare Ltd (www.pedicat.com).
1. Haley SM, Coster WJ, Ludlow LH, Haltiwanger JT, Andrellos PA. Pediatric Evaluation of Disability Inventory: Development, Standardization and Administration Manual. Boston, MA: Trustees of Boston University; 1992.
2. Ahl L, Johansson E, Granat T, Brogren Carlberg E. Functional therapy for children with cerebral palsy: an ecological approach. Dev Med Child Neurol. 2005;47(9):613-619.
3. Ziviani J, Ottenbacher K, Shephard K, Foreman S, Astbury W, Ireland P. Concurrent validity of the Functional Independence Measure for children (WeeFIM) and the Pediatric Evaluation of Disabilities Inventory in children with developmental disabilities and acquired brain injuries. Phys Occup Ther Pediatr. 2001;21(2-3):91-101.
4. Nichols D, Case-Smith J. Reliability and validity of the Pediatric Evaluation of Disability Inventory. Pediatr Phys Ther. 1996;8(1):15-24.
5. Haley SM, Coster WJ, Kao YC, Dumas HM, Fragala-Pinkham MA, Kramer J, Ludlow LH, Moed R. Lessons from use of the Pediatric Evaluation of Disability Inventory (PEDI): Where do we go from here? Pediatr Phys Ther. 2010;22(1):69-75.
6. Cella D, Gershon R, Lai J, Choi S. The future of outcomes measurement: item banking, tailored short-forms, and computerized adaptive assessment. Qual Life Res. 2007;16(Suppl 1):133-141.
7. Haley SM, Coster WJ, Dumas HM, Fragala-Pinkham MA, Kramer J, Ni PS, Feng T, Kao YC, Moed R, Ludlow LH. Accuracy and precision of the Pediatric Evaluation of Disability Inventory Computer Adaptive Test (PEDI-CAT) for children 0 to 21 Years. Dev Med Child Neurol. 2011;53(12):1100-1106.
8. Haley SM, Coster WJ, Dumas HM, Fragala-Pinkham MA, Moed R. Pediatric Evaluation of Disability Inventory Computer Adaptive Test (PEDI-CAT), Version 1.3.6, Development, Standardization and Administration Manual. CRECare, LLC; 2012.
9. Slavin MD, Kisala PA, Jette AM, Tulsky DS. Developing a contemporary functional outcome measure for spinal cord injury research. Spinal Cord. 2010;48(3):262-267.
10. Jette AM, McDonough CM, Haley SM, Ni P, Olarsch S, Latham N, Hambleton RK, Felson D, Kim YJ, Hunter D. A computer-adaptive disability instrument for lower extremity osteoarthritis research demonstrated promising breadth, precision, and reliability. J Clin Epidemiol. 2009;62(8):807-815.
11. Norweg A, Ni P, Garshick E, O'Connor G, Wilke K, Jette AM. A multidimensional computer adaptive test approach to dyspnea assessment. Arch Phys Med Rehabil. 2011;92(10):1561-1569.
12. Dumas HM, Fragala-Pinkham MA, Haley SM, Coster WJ, Ying-Chia Kao, Kramer J, Moed R. Item bank development for a revised Pediatric Evaluation of Disability Inventory (PEDI). Phys Occup Ther Pediatr. 2010;30(3):168-184.
13. Dumas HM, Fragala-Pinkham MA, Feng T, Haley SM. A Preliminary Evaluation of the PEDI-CAT Mobility Item Bank for Children Using Walking Aids and Wheelchairs. J Pediatr Rehabil Med. 2012;5(1):29-35.
14. Dumas HM, Fragala-Pinkham MA, Haley SM, Ni P, Coster W, Kramer JM, Kao YC, Moed R, Ludlow LH. Computer adaptive test performance in children with and without disabilities: prospective field study of the PEDI-CAT. Disabil & Rehabil. 2012;34(5):393-401.
15. Dumas HM, Fragala-Pinkham MA. Concurrent Validity and Reliability of the Pediatric Evaluation of Disability Inventory-Computer Adaptive Test Mobility Domain. Pediatr Phys Ther. 2012;24(2):171-176.
Helene Dumas and Maria Fragala-Pinkham are physical therapists and work in the Research Center at Franciscan Hospital for Children. They are the senior authors of the PEDI-CAT.