Validity and Reliability of the Frontotemporal Dementia Rating Scale (FTD-FRS) for the Progression and Staging of Dementia in Brazilian Patients

Abstract

Introduction:Few studies on instruments for staging frontotemporal dementia (FTD) have been conducted.Objective:The objective of this study was to analyze the factor structure, internal consistency, reliability, and convergent validity of the Brazilian version of the Frontotemporal Dementia Rating Scale (FTD-FRS).Methods:A total of 97 individuals aged 40 years and above with >2 years' education took part in the study, 31 patients diagnosed with behavioral variant FTD (bvFTD), 8 patients with primary progressive aphasia, 28 with Alzheimer disease, 8 with mild cognitive impairment, and a control group of 22 healthy subjects. The FTD-FRS was completed by family members or caregivers, and Neurologists completed the 8-item Clinical Dementia Rating for Frontotemporal Lobar Degeneration (CDR-FTLD) scale (6 original domains plus Language and Behavior). The Alzheimer disease and FTD patients had equivalent disease severity level.Results:The internal consistency of the FTD-FRS, estimated by Cronbach , was 0.975 whereas test-retest reliability was 0.977. Scree plot and exploratory factor (Varimax rotation) analyses revealed the existence of 4 factors, with eigenvalues >1, which together explained 77.13% of the total variance with values of 1.28 to 17.52. The domains of the Brazilian version of the FTD-FRS scale correlated with the domains of the CDR-FTLD.Conclusions:The present study is the first to document the factorial structure of the FTD-FRS and its convergent validity with the CDR-FTLD. These tools are key to determine dementia severity in FTD. The Brazilian FTD-FRS demonstrated adequate psychometric properties for use in Brazil. This instrument may contribute to disease staging in FTD and may help to document intervention-related changes.