Noriaki Harada

Prevalence of Raynaud's phenomenon in Japanese males and females

In order to estimate the prevalence rate of Raynauds phenomenon in the Japanese population, 1875 males and 1998 females were interviewed by medical doctors, aided by a typical photograph of Raynauds phenomenon. The prevalence rates were 3.3% in males and 2.5% in females. Approximately 60% of the male cases of Raynauds phenomenon were presumed to be caused by vibration syndrome or trauma to the fingers. Prevalence rates excluding these two causes were 1.2% in males and 2.2% in females. The male:female ratio of these prevalence rates was 1:1.9. The prevalence rate for males increased with age, while that for females tended to decrease. The male:female ratio for subjects under 50 years old was 1:5.2 and for those 50 years old or older the ratio was 1:1.1. The prevalence rates of symptoms limited to finger whitening, excluding cases caused by vibration syndrome or trauma, were 1.0% in males and 1.8% in females. Both of these prevalence rates were lower than those of male and female Caucasians.

Correlation between vibration-induced white finger and symptoms of upper and lower extremities in vibration syndrome

SummaryThe correlation was investigated between the frequency of attacks of vibration-induced white finger (VWF) and numbness or coldness of the fingers and legs in patients with vibration syndrome. Some 1687 patients with vibration syndrome were examined and of these 342 chain-saw operators and 277 rock-drill operators had no disease other than vibration snydrome. Then subjects were matched by age and period of treatment within three years. In the last analysis, 20 in the VWF “almost everyday” group or in the “never” group, and 40 in the “occasionally” group were selected from the chain-saw operators, and from the rock-drill operators 32 in the VWF “everyday” or the “never” group and 64 in the “occasionally” group. The present study showed that, with the frequency of VWF attacks, patients had a higher prevalence of coldness not only in the fingers but also in the legs. These findings suggest a correlation between the severity of circulatory disturbances of the upper extremities and that of the lower ones in patients with vibration syndrome. Further studies on circulatory disturbances in the leg are required.

Validity of various function tests performed in Japan as a screening test for vibration syndrome

SummaryIn Japan, various function tests on the upper extremities are widely performed for the early diagnosis of vibration syndrome. The validity of these function tests was investigated by discriminant function analysis. The correct classification rate of the 120 workers exposed to vibration and the 40 control workers was 83.1%, when including the exposure-to-cold test. Therefore, the function tests were confirmed to be of diagnostic significance as a screening test for vibration syndrome. However, the rate is not sufficient to make a diagnosis only with the function tests. When not including the exposure-to-cold test, the rate was reduced by 10% because insidious functional disorders were missed in the early stage. For the early diagnosis of vibration syndrome, the exposure-to-cold test should be included in the function tests. Furthermore, to enhance the validity of the diagnosis, the results of the function tests should be evaluated together with subjective symptoms and the findings on bones and joints, the central nervous system and the endocrine system.

Heart rate variation and serum dopamine-beta-hydroxylase activity in workers exposed to vibration

SummaryTests of autonomic nervous function were conducted on 38 workers who had been exposed to vibration [16: VWF(+) group, 22: VWF(−) group, VWF: vibration-induced white finger] and 17 workers who had not been exposed to vibration (control group). Measurements were made of R-R interval variation of the electrocardiogram at rest and during deep breathing, and serum dopamine-beta-hydroxylase (DBH) activity during an immersion test of the hand in 10°C water. Heart-rate variation related to respiratory arrhythmia indicates parasympathetic activity, and serum DBH activity is regarded as an indicator of sympathetic activity. The variations in the R-R interval during deep breathing were smallest in the VWF(+) group, followed by the VWF(−) group (P< 0.05 and P<0.01, compared with the control group). The DBH activity of the VWF(+) group was larger than those of the VWF(−) group and the control group, however, the differences were small and not statistically significant. The reduced R-R interval variations in the VWF(+) and the VWF(−) groups support the hypothesis that autonomic nervous function can be affected by exposure to vibration. The change of DBH activity induced by cold exposure may be an unsuitable index of sympathetic tone. Further study of the autonomic nervous function in workers with vibration syndrome is recommended.

Living and working conditions, and the effect on health problems of women employed in a factory in rural district.

農村婦人の農外就労が増加している。愛媛県松山市近郊の農村地城に位置する重信町でも, 女子就業者にしめる雇用者の割合が1960年の24.8%から1980年の61.1%へと増加している。同町のN製缶工場に勤務していた農村婦人の生活と健康について調査した。その結果, 同工場就労婦人の属する家庭の経済状態が不安定であること, 同工場における労働条件にも種々の問題があり, 業務に起因すると疑われた健康障害の発生が多いことが明らかになった。農村地域における不安定な雇用条件を背景にした農村進出工場の労働条件と, そこに勤務する農村婦人の健康問題についてさらに検討する必要があると考えられた。

A study of eight subjective symptoms concerned with the so-called "farmer's syndrome" as a health indicator.

愛媛県内の農村地域で実施した循環器検診で得られた資料を解析し, 現代の農村地域での健康管理活動における農夫症8症候の意義を検討した。その結果, 農夫症8症候の訴えは農村社会の変貌とともに減少してきているが健康指標2しての役割は消失していないこと, しかし, 農業労働の多様化や兼業化の進行による生活条件や労働条件の変化を農夫症8症候に反映させる必要があることなどを考察した。