OBJECTIVE: Since the 1990s the Functional Independence Measure (FIM™) was believed to measure 2 different constructs, represented by its motor and cognitive subscales. The practice of reporting FIM™ total scores, together with recent developments in the understanding of the influence of locally dependent items on fit to the Rasch model, raises the question of whether the FIM™ 18-item version can be reported as a unidimensional interval-scaled metric. DESIGN: Rasch analysis of the FIM™ using testlet approaches to accommodate local response dependency. PATIENTS: A calibration sample containing 946 cases of data from 11,103 patients undergoing neurological or musculoskeletal rehabilitation in Switzerland in 2016. RESULTS: Baseline analysis and the traditional testlet approach showed no fit with the Rasch model. When items were grouped into 2 testlets, fit to the Rasch model was achieved, indicating unidimensionality across all 18 items. A transformation table to convert FIM™ raw ordinal scores to the corresponding Rasch interval scaled values was created. CONCLUSION: This study provides evidence that FIM™ total scores represent a unidimensional set of items, supporting their use in clinical practice and outcome reporting when applying the respective transformation table. This provides a basis for standardized reporting of functioning.
OBJECTIVE: Since the 1990s the Functional Independence Measure (FIM™) was believed to measure 2 different constructs, represented by its motor and cognitive subscales. The practice of reporting FIM™ total scores, together with recent developments in the understanding of the influence of locally dependent items on fit to the Rasch model, raises the question of whether the FIM™ 18-item version can be reported as a unidimensional interval-scaled metric. DESIGN: Rasch analysis of the FIM™ using testlet approaches to accommodate local response dependency. PATIENTS: A calibration sample containing 946 cases of data from 11,103 patients undergoing neurological or musculoskeletal rehabilitation in Switzerland in 2016. RESULTS: Baseline analysis and the traditional testlet approach showed no fit with the Rasch model. When items were grouped into 2 testlets, fit to the Rasch model was achieved, indicating unidimensionality across all 18 items. A transformation table to convert FIM™ raw ordinal scores to the corresponding Rasch interval scaled values was created. CONCLUSION: This study provides evidence that FIM™ total scores represent a unidimensional set of items, supporting their use in clinical practice and outcome reporting when applying the respective transformation table. This provides a basis for standardized reporting of functioning.
Authors: Roxanne Maritz; Cristina Ehrmann; Birgit Prodinger; Alan Tennant; Gerold Stucki Journal: Int J Qual Health Care Date: 2020-07-20 Impact factor: 2.038
Authors: Reem M Alwhaibi; Noha F Mahmoud; Mye A Basheer; Hoda M Zakaria; Mahmoud Y Elzanaty; Walaa M Ragab; Nisreen N Al Awaji; Hager R Elserougy Journal: Int J Environ Res Public Health Date: 2021-01-12 Impact factor: 3.390