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

Background: Intermittent claudication (IC) occurs in patients with peripher al occlusive arterial disease and results in leg pain after walking a certa in distance - the claudication distance. Until recently, no specific questi onnaire has been available to measure quality of life in patients with IC. Objectives: To validate the Claudication Scale (CLAU-S) questionnaire in pa tients in France, the UK, Germany and Belgium. Methods: Patients completed the CLAU-S questionnaire and provided demograph ic and clinical data. Pooled data were examined for psychometric and struct ural validity and test-retest reliability. Structural equation modelling (S EM) was used to confirm that the questionnaire was measuring the causal rel ationships 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 discrim inant coefficients and internal consistency reliability coefficients met or exceeded standard criteria. Principal component analysis confirmed the fac torial 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 la nguages.