Content » Vol 47, Issue 5

Original report

Rasch validation of the Prosthetic Mobility Questionnaire: A new outcome measure for assessing mobility in people with lower limb amputation

Franco Franchignoni, Marco Monticone, Andrea Giordano, Barbara Rocca
Scientific Institute of Veruno, Salvatore Maugeri Foundation, Via Revislate 13, IT-28010 Veruno (NO), Italy
DOI: 10.2340/16501977-1954


Objective: To create a new outcome measure of mobility in people with lower limb amputation, based on a pool of 14 items assessing prosthetic mobility, comprising the 12-item Prosthesis Evaluation Questionnaire (Mobility Section) plus 2 new items.
Design: Cross-sectional study.
Subjects: A total of 100 subjects (median age 58 years; 46 males; median body mass index 23. 8) who had recently undergone lower limb amputation.
Methods: Each patient completed the 14-item questionnaire twice: (i) at admission to the rehabilitation unit for prosthetic rehabilitation training; (ii) at 6-month follow-up after discharge.
Results: After Rasch analysis, 2 items were deleted (one due to misfit, the other because showing large (>  0. 30) positive correlation of residuals with two other items (local dependence). The remaining items fitted the Rasch model (internal construct validity), giving a new 12-item scale with a 5-level response format, the Prosthetic Mobility Questionnaire (PMQ), which demonstrated unidimensionality, lack of differential item functioning, and good reliability indices (person-separation reliability = 0. 87; Cronbach’s alpha 0. 88).
Conclusion: Although further studies are needed to increase confidence in clinical use of the PMQ, this new questionnaire appears to be a promising, psychometrically-sound patient-reported outcome measure for assessment of mobility in subjects with lower limb amputation who use a prosthesis.

Lay Abstract


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