Plethysmographic cold test for diagnosis and evaluation of the severity of Raynaud's phenomenon. Validation of the method by factorial analysis of correspondences in 541 patients.

The purpose of this study was to analyze the reactivity to cold in a series of 541 patients with Raynaud's phenomenon and to search for possible correlations with the functional severity and the etiologic diagnosis of the acrosyndrome. Digital reactivity to cold was quantified by a plethysmographic cold test performed under standardized conditions, using mercury-strain-gauge plethysmography. The functional severity of Raynaud's phenomenon was assessed by the weekly frequency of attacks during winter. Topographic evaluation of the acrosyndrome sought to determine the possible extension of attacks to the thumb. Factorial Analysis of Correspondences indicated a high correlation between the intensity of reactivity to cold and the frequency of thumb involvement (p = 0.0001) or the weekly frequency of attacks during winter (p < 10(-4)). There was also a close dependence between reactivity to cold and the etiologic diagnosis of the acrosyndrome (p < 10(-4)). Significant correspondences were found between mild or major types of reactivity and primary Raynaud's disease, between very severe reactivity to cold and scleroderma. This study contributes to a clinical validation of the plethysmographic cold test. During Raynaud's phenomenon, it is indicative of clinical severity and can in a certain way guide the etiologic diagnosis, particularly concerning the risk of scleroderma.