A comparison of questionnaires for assessing physical function in patients with lower extremity bone metastases

To assess, (i) the degree to which the: PROMIS Physical Function Cancer, PROMIS Neuro-QoL Mobility, Toronto Extremity Salvage Score (TESS), Lower Extremity Function Score (LEFS), and Musculoskeletal Tumor Society score (MSTS), measure physical function; (ii) differences in coverage and reliability; and (iii) difference in completion time. One hundred of 115 (87%) patients with lower extremity metastases participated in this prospective study. We used exploratory factor analysis-correlating questionnaires with an underlying trait-to assess if questionnaires measure the same. Coverage was assessed by floor and ceiling effect and reliability by the standard error of measurement (SEM). Completion time was compared using the Friedman test. All questionnaires measured the same concept; demonstrated by high correlations (>0.7). Floor effect was absent, while ceiling effect was present in all, but highest for the PROMIS Neuro-QoL Mobility (7%). The SEM was below the threshold-indicating reliability-over a wide range of ability levels for the PROMIS-Physical Function, TESS, and LEFS. Completion time differed between questionnaires (P