[Differences in the prevalences of Raynaud's phenomenon in general populations living in a mountain area and in a plain area].

Raynaud's phenomenon (RP) which is the episodic and reversible vascular spasm of the extremities can be elicited by cold or emotional changes. RP has been classified into two groups. One is primary Raynaud's phenomenon (PRP) with no identifiable underlying disease and/or cause, and the other is the secondary form of RP (Raynaud's syndrome) with underlying disease and/or cause, e.g., collagen disease, trauma, vibration from vibrating tools, etc. In the present study using this definition of RP the prevalences of RP were studied in general populations in a mountain village "T" and in a town "K" located in a plain area in Gifu prefecture, Japan. The prevalences of RP in T Village were 8.0% (25/314) in males and 3.5% (16/454) in females, and in K Town 2.7% (7/259) in males and 3.2% (21/657) in females. In 52% of the male cases in T Village it was estimated that the exposure to vibration from vibrating tools was the cause of RP. In K Town no male cases of RP were induced by vibration. Exposure to vibration may be one of the important factors when prevalences of RP are investigated in various areas. There were no significant differences between the two areas in the prevalences of PRP (T Village: male 2.9%, female 3.1%; K Town: male 2.7%, female 2.9%). The annual mean air temperature was usually 5-6 degrees C lower in T Village than that in K Town. From the results of this study the differences in the mean air temperature did not appear to have a significant influence on the prevalence of PRP in each area.