Objective: To determine the population based prevalence of Raynaud's phenomenon (RP) in 5 geographic regions: one in South Carolina, USA, and 4 in France; to explore the relationship of RP to the climate; to investigate possible risk factors; and to describe the characteristics of RP+ subjects in the general population.
Methods: The study consisted of 2 phases: a telephone survey of a randomly drawn sample of households, with 10,149 completed interviews; these were followed by a face to face interview and clinical evaluation (n = 1,534), including diagnosis of RP. The same methodology was used in all 5 regions: for recruitment of subjects, criteria for RP, method of RP diagnosis, and for gathering additional information.
Results: The prevalence of RP was found to be related to the climate. The relationship between RP and climate was complicated, however, by the fact that many subjects had moved between climate zones. The relationship of RP to a cold climate became more evident after taking the migration patterns into account: the majority of RP+ subjects in the 2 coldest regions had lived all their lives in the same or a similar climate zone; the majority of RP+ subjects in the 2 warmest regions had previously lived in a colder climate. Other factors associated with RP were family history of RP, cardiovascular diseases, older age, a low body mass index, use of vibrating tools, and outings of a day or more. The classical triphasic RP was rarely encountered in the general population and the most frequently observed signs and symptoms during an RP attack were blanching accompanied by numbness.
Conclusion: In addition to being a triggering factor for RP attacks, cold also appears to be an etiologic factor in the pathogenesis of RP. A subclinical cold injury, more likely to occur in colder climates, may be responsible for the "local fault" that has been implicated in the pathogenesis of RP and, in association with other risk factors, may predispose subjects to develop clinical RP.