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 l imbs. Initially developed in Germany, the scale has been translated into Fr ench 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 Livi ng" "Pain"; "Social Life"; "Disease-specific anxiety"; and "Mood", for a to tal 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 co nfirmed. Analysis of structural validity showed grouping of items in accord ance with initial Scale construction and a clear separation between the dif ferent 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 mathemati cal technique called Structural Modelling Equations was used on this QoL in strument. It related the causal structure of the QoL components in peripher al arterial disease of the lower limbs (stage 2). An indisputable causal re lationship was demonstrated between clinical parameters, particularly walki ng distance, and the QoL components. The classical symptom-deficit-disabili ty causal structure of disease- specific QoL questionnaires was also studie d. In particular, we found an essential relationship between the Daily Livi ng dimension and, to a lesser extent, the Social Life activities and Diseas e- specific anxiety dimension, and QoL. The Pain dimension proved to be an explanatory variable of the other QoL components without being directly rel ated to QoL. Finally, the Mood dimension was a resultant variable of QoL an d not an explanatory variable of QoL. This study therefore enabled validation of the psychometric properties of t he French version of CLAU-S and also demonstrated the complementary roles o f walking distance and QoL in the management of patients with intermittent claudication.