日本における潰瘍性大腸炎の統計

A Statistical Survey of Ulcerative Colitis in Japan

　かつて稀であるとされていた潰瘍性大腸炎（CUと略）が，ある時期から急に増加したことが真実であれば，その原因を追究することが病気の成立にかかわる因子を解明する手掛りとなる．それには適正な疫学的解析が重要である．集計を開始してわずか3年で時期尚早ではあるが，許される範囲内で試みた解析結果をならべて私見を述べてみる．

　A nation-wide survey of patients with ulcerative colitis examined since 1968 has been made in the form of questionnaire from 2,408 institutions all over the country. As of April 20, 1976, the number of institutions treating such a case was 487 with 2,116 cases (1,022 males and 1,094 females). The morbidity rate of ulcerative colitis is 1.890 persons per 100,000 population. From 1968 to 1972 the yearly morbidity rate increased in the manner of quadratic function. In 1973 the rate was lower (0.248 person). It was almost the same in 1974.

　1. The trends for higher rate of incidence were seen in areas where the population rate of the age group 20～29 was high, in areas of higher cultural standards and in those with denser population.

　2. No difference was seen between the male and female in the yearly change of morbidity rate, but its age distribution showed that until the age of 29 the male was more often affected. After 30 it was the other way around.

　3. Proctitis was seen in about 11 per cent. We think that there must be a large number of unreported cases in this country.

　4. Age-adjusted distribution of yearly morbidity, although different year by year, showed that on an average a peak incidence was seen in the age group 20～29. With advancing years the disease lessened. There was no so-called secondary peak.

　5. The age distribution of morbidity differed between the colonic type and rectosigmoid type. No regional difference was seen.

　6. The onset of the disease showed no great seasonal changes.

　7. People in densely populated areas were affected by the disease before the age of 39 more often than those in less populated areas.

　8. No significant difference of morbidity was seen among the blood groups (ABO). We hope that HLA study would come up to our expectations.

　9. Familial occurrence was reported in 23 cases among 11 family trees. It was most prominent between mother and daughter.

　10. Our investigations were done four times, but owing to the limited time for study, they are insufficient to determine how accurately our sampling groups reflected the actual conditions of the overall patients of ulcerative colitis in Japan. At present, we cannot also make out the implication of the change in the curve of yearly morbidity with the year 1972 at its peak.