International validation of the CLAU-S quality-of-life questionnaire for use in patients with intermittent claudication

Abstract

Background: Intermittent claudication (IC) occurs in patients with peripheral occlusive arterial disease and results in leg pain after walking a certain distance - the claudication distance. Until recently, no specific questionnaire has been available to measure quality of life in patients with IC.

Objectives: To validate the Claudication Scale (CLAU-S) questionnaire in patients in France, the UK, Germany and Belgium.

Methods: Patients completed the CLAU-S questionnaire and provided demographic and clinical data. Pooled data were examined for psychometric and structural validity and test-retest reliability. Structural equation modelling (SEM) was used to confirm that the questionnaire was measuring the causal relationships involved in IC in each of the language groups studied.

Results: Cross-sectional and factor analysis confirmed the validity of the questionnaire in the pooled patient population. Item convergent and discriminant coefficients and internal consistency reliability coefficients met or exceeded standard criteria. Principal component analysis confirmed the factorial structure. The underlying causal relationships in IC were identified using SEM and were consistent in all language groups studied.

Conclusions: The CLAU-S questionnaire has undergone validation in English, French, German and Flemish and has a very satisfactory validity in these languages.