A new valid Walking Aid Scale better predicts distance walked by prosthesis users than Prosthetic Mobility Questionnaire 2.0 and Activities-Specific Balance Confidence Scale

Head-to-head Rasch comparison of the Prosthesis Evaluation Questionnaire-Mobility Section and the Prosthetic Mobility Questionnaire 2.0 in Italian lower-limb prosthesis users

BACKGROUND

The Prosthesis Evaluation Questionnaire-Mobility Section (PEQ-MS) and the Prosthetic Mobility Questionnaire (PMQ 2.0) are two validated self-report questionnaires assessing mobility in people with lower-limb amputation.

OBJECTIVE

The aim of this study was to assess and compare the psychometric properties of PEQ-MS and PMQ 2.0 in a sample of 100 Italian lower-limb prosthesis users.

METHODS

We conducted a secondary Rasch analysis of data from a prospective single-group observational study, comparing the PEQ-MS and PMQ 2.0 head to head and then cocalibrating them onto a common interval-scaled metric, through common-person equating, to compare their operational range.

RESULTS

The PMQ 2.0 showed good measurement qualities. The PEQ-MS had acceptable psychometric properties, despite some weakness in item selection. Cocalibration of the two questionnaires indicated that they assess the same underlying construct (prosthetic mobility), but PMQ 2.0 items have a wider range of difficulty (by one logit). Finally, we created a nomogram allowing to "cross-walk" between scores of the two questionnaires.

CONCLUSIONS

Comparison of the two questionnaires showed that the PMQ 2.0 has a better measurement performance and larger operational range than the PEQ-MS, making it more suitable for assessing lower-limb prosthesis users with a large range of locomotor abilities, in particular those with higher mobility levels.

Rasch validation and comparison of the German versions of the Locomotor Capabilities Index-5 and Prosthetic Mobility Questionnaire 2.0 in lower-limb prosthesis users

This study aimed to compare, through Rasch analysis, the psychometric properties of the Locomotor Capabilities Index (LCI-5) and Prosthetic Mobility Questionnaire (PMQ 2.0) in German lower-limb prosthesis users. The questionnaires were concurrently administered to a convenience sample of 98 consecutively recruited individuals with lower limb amputation (LLA) (male/female = 61/37; mean age 57 ± 14 years). LCI-5 showed disordered rating scale thresholds (one response option in three items required collapsing); local dependence between two items (resolved by creating a testlet); underfit of one item ('Get up from the floor'); and presence of a second weak dimension. PMQ 2.0 showed a correctly functioning rating scale; good fit of the data to the model (apart from some overfit); local dependence between two items (absorbed by creating a testlet); and essential unidimensionality. At scale co-calibration onto a common interval-scaled metric, PMQ 2.0 was better targeted than LCI-5 (i.e. the extent of item difficulty was more appropriate for the sample) and its operational range allowed a more precise measurement of higher locomotor abilities. The correlation between LCI-5 and PMQ 2.0 scores was rho =  0.78. In conclusion, LCI-5 revealed some drawbacks, confirming a previous Rasch study; refinement of its rating scale and item selection seems therefore warranted. The PMQ 2.0 demonstrated good overall measurement quality, in line with previous Italian and Slovene studies. The operational range of the PMQ 2.0 makes it more suitable than LCI-5 for assessing people with high locomotor abilities.