The accuracy of the Adapted Brazilian Functionality Index in assessing disability severity

Abstract

This article describes accuracy measurements against a reference scale from the Brazilian project to validate the Brazilian Functionality Index Applied for Retirement Purposes (IFBRA) for authorizing eligibility for early retirement. The IFBRA assesses the functionality of Persons with Disabilities (PwDs) by combining the International Classification of Functioning, Disability and Health, the Functional Independence Measure, and performance and barriers to classify severity levels. It represents the third phase of a nationwide validation study. Accuracy was derived from a census survey of spontaneous demand to determine eligibility for early retirement and assessed sensitivity, specificity, and effectiveness compared to the standard scale constructed for this study. The nationwide survey assessed the best agreement between physicians’ and social workers’ assessments of disability severity of insured PwDs workers. Maximum effectiveness and performance with sensitivity and specificity of 85% occurred when we combined the two professional raters’ sum scores with cutoff points at respective percentiles and absolute values of the evaluator pairs at 20% – 6,060, 43% – 6,750, and 84% – 7,750. The IFBRA demonstrated high accuracy, validity, and effectiveness according to the reference standard.