Transcultural adaptation and validation of the Spanish-language version of ACTIVLIM in adults with inherited myopathies using the Rasch model.

Abstract

INTRODUCTION\nACTIVLIM is an instrument for the measurement of activity limitations in patients with neuromuscular disorders. The aim of this study is to establish a transcultural adaptation and psychometric validation of the Spanish-language version of ACTIVLIM in a sample of Spanish patients with inherited myopathies.\n\n\nPATIENTS AND METHOD\nA Spanish-language version of ACTIVLIM was developed using the translation/back translation method. The questionnaire was administered to 135 patients with inherited myopathies. The psychometric properties of the questionnaire were assessed using the Rasch model. Floor and ceiling effects were estimated. Unidimensionality was evaluated with a principal component analysis of the residuals of the model, and using infit and outfit statistics. We estimated reliability with the person separation reliability index and invariance with differential item functioning. External construct validity was tested through correlation with the Brooke scale, the Vignos scale, the Functional Independence Measure scale, and floor-to-stand time. Test-retest reliability was evaluated with the intraclass correlation coefficient and differential item functioning.\n\n\nRESULTS\nThe psychometric analysis of the Spanish-language version of ACTIVLIM demonstrated that floor effect was absent, although a modest ceiling effect was identified. The instrument displayed unidimensionality, good internal consistency, external construct validity, and good test-retest reliability.\n\n\nCONCLUSION\nThe Spanish-language version of ACTIVLIM is a valid and reliable measurement instrument for assessing activity limitations in patients with inherited myopathies.