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Psychometric validation of a patient‐reported measure of physical functioning in sporadic inclusion body myositis
Author(s) -
Williams Valerie,
Coles Theresa,
Gnanasakthy Ari,
Demuro Carla,
Yarr Stuart,
Williams Nicole,
Lowes Linda,
Alfano Lindsay,
Tseng Brian
Publication year - 2016
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.25080
Subject(s) - cronbach's alpha , reliability (semiconductor) , convergent validity , intraclass correlation , construct validity , medicine , physical therapy , physical medicine and rehabilitation , inclusion body myositis , psychology , psychometrics , clinical psychology , myositis , internal consistency , power (physics) , physics , quantum mechanics
: To assess self‐reported physical functioning in patients with sporadic inclusion body myositis (sIBM), the sIBM Physical Functioning Assessment (sIFA) was developed. This research establishes the validity, reliability, and responsiveness of the sIFA in patients with sIBM. Methods : Data from 3 small, noninterventional, observational studies were analyzed. Several measures of physical function were included to assess validity. Reliability (Cronbach alpha, test–retest intraclass correlations), construct validity (correlations, analyses of variance), and responsiveness (effect size estimates) were evaluated. Results : Cronbach alphas (range = 0.86–0.91) and test–retest reliability (0.91) were highly satisfactory. Correlations with other measures provided evidence of convergent validity. sIBM patients able to walk without assistive devices scored significantly better on the sIFA (means = 36.0–47.05) than those who required power mobility or wheelchairs (means = 54.9–71.5), demonstrating the discriminating ability of the sIFA. Effect size estimates of responsiveness suggested mild functional progression. Conclusions : Psychometric analyses of the sIFA demonstrate satisfactory reliability, validity, and responsiveness. Muscle Nerve 54 : 658–665, 2016