Validation of the Amputee Single Item Mobility Measure (AMPSIMM) and the abbreviated AMPSIMM-4 for amputee mobility

ObjectiveTo evaluate the criterion and construct validity of the 7-category Amputee Single Item Mobility Measure (AMPSIMM) in a large contemporary dysvascular lower limb amputation population and propose an abbreviated 4-category version (AMPSIMM-4) whose mobility categories parallel the Medicare Functional Classification Levels (K-levels).DesignCohort study retrospectively identifying persons with their first lower limb amputation then prospectively collecting their self-reported mobility.SettingNational cohort identified through a large Veterans' Administration dataset.ParticipantsSix hundred and ninety-two participants aged 30 years and older, undergoing their first diabetes and/or peripheral artery disease-related amputation at the transmetatarsal, transtibial, or transfemoral level, with a subset of 60 consecutive participants with a self-reported K-level.Main measuresAMPSIMM, Locomotor Capability Index-5 (LCI-5), K-levels, and PROMIS Global-10 Physical (PROMIS-P), at one year post amputation.ResultsThe strength of the correlation between AMPSIMM and LCI-5 scores was large (Spearman's rho = .88; <i>p</i> < .0001). The correlation with PROMIS-P scores was 0.67 (<i>p</i> < .0001). The strength of the correlation between the AMPSIMM-4 and self-reported K-levels was large (Spearman's rho = .82; <i>p</i> < .0001).ConclusionsThe AMPSIMM is a clinician-friendly single-item patient-reported measure that can capture a broad range of lower limb amputation mobility, from wheelchair to advanced community ambulation, with or without a prosthesis, and with or without ambulation aids. It demonstrates strong criterion and construct validity. The AMPSIMM-4 can be generated directly from the AMPSIMM with descriptors that are very similar to and are highly correlated with self-reported K-levels.