[Intermittent claudication and quality of life. Psychometric validation of the French version of the CLAU-S questionnaire].

CLAU-S is a disease-specific quality of life (QoL) scale for patients with intermittent claudication due to peripheral arterial disease of the lower limbs. Initially developed in Germany, the scale has been translated into French according to classical forward/backward methodology. The objective of this study was to test the validity of the French version of CLAU-S. In its current format, the CLAU-S scale evaluates 5 dimensions: "Daily Living"; "Pain"; "Social Life"; "Disease-specific anxiety"; and "Mood", for a total of 47 items. The QoL scores and clinical findings in 157 patients with intermittent claudication were analysed. Validation of the convergence and discriminatory power of the scale were confirmed. Analysis of structural validity showed grouping of items in accordance with initial scale construction and a clear separation between the different dimensions. Analysis of the internal reliability of the questionnaire confirmed the good internal coherence of these dimensions. Reproducibility of the scores over time was confirmed by test-retest analysis. In addition to the actual validation of CLAU-S, a new, innovative mathematical technique called Structural Modelling Equations was used on this QoL instrument. It related the causal structure of the QoL components in peripheral arterial disease of the lower limbs (stage 2). An indisputable causal relationship was demonstrated between clinical parameters, particularly walking distance, and the QoL components. The classical symptom-deficit-disability causal structure of disease- specific QoL questionnaires was also studied. In particular, we found an essential relationship between the Daily Living dimension and, to a lesser extent, the Social Life activities and Disease- specific anxiety dimension, and QoL. The Pain dimension proved to be an explanatory variable of the other QoL components without being directly related to QoL. Finally, the Mood dimension was a resultant variable of QoL and not an explanatory variable of QoL. This study therefore enabled validation of the psychometric properties of the French version of CLAU-S and also demonstrated the complementary roles of walking distance and QoL in the management of patients with intermittent claudication.