Validity and reliability of the Functioning Disability Evaluation Scale-Adult Version based on the WHODAS 2.0-36 items

Background/Purpose: The disability eligibility determination system is based on the International Classification of Functioning, Disability and Health (ICF) framework in Taiwan. The Functioning Disability Evaluation Scale (FUNDES) has been developed since 2007 for assessing the status of an individual's activities and participation in the disability eligibility system. The purpose of this study was to examine the reliability and validity of the FUNDES-Adult Version (FUNDES-Adult). Methods: During 2011-2012, a total of 5736 adults with disabilities (aged 58.4±18.2 years) were randomly recruited for a national population-based study. These adults were assessed in person by certified professionals in the authorized hospitals. Domains 1-6 of the FUNDES-Adult addressing the performance and capability dimensions are modified from the World Health Organization Disability Assessment Schedule 2.0-36-item version, and Domain 7 (Environmental attribute) and capability and capacity dimensions of Domain 8 (Motor action) are designed based on the ICF coding system. Results: The internal consistency was excellent (Cronbach's α≥0.9). An exploratory factor analysis yielded a five-factor FUNDES structure with a variance of 76.1% and 76.9% and factor loadings of 0.56-0.94 and 0.55-0.94 for the performance and capability dimensions, respectively. The factor loadings for the second-order confirmatory factor analysis for the performance and capability dimensions were from 0.81 to 0.89. In Domains 1-6 and 8, the ceiling effects were from 9% to 36%, and the floor effects were from 5% to 45%. Conclusion: FUNDES-Adult has acceptable reliability and validity and can be used to measure activities and participation for people with disabilities.