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.