The association between bowel habits and colorectal neoplasms was studied in a case-control study involving 520 cases with colorectal adenoma, 217 cases with colorectal cancer, 638 hospital controls without no endoscopical findings in the large intestine and 577 population controls. Compared with population controls, the relative risk (RR) for soft stools were in-creased for every site of colorectal adenoma and cancer and that for hard stools was increased for colon adenoma and cancer. However, these associations were not observed with hospital controls. The RRs for rectal and distal colon adenomas and rectal cancer, compared with either control group, progressively increased with increasing the number of bowel movements.The RR for two or more bowel movements per day, adjusted for other confounding factors, was 2.11 (95% confidence interval (CI): 1.24-3.60) for distal colon adenoma, 3.52 (95% CI : 1.56-7.93) for rectal adenoma and 7.72 (95% Cl : 3.18-18.76) for rectal cancer, compared with hospital controls. All of the associations are not likely to be explained by effects of disease. These results suggest that bowel habits indicating diarrhea and underlying inflammation may increase the risk of neoplasms in the distal colon and rectum. J Epidemiol, 1993; 3 : 1-5.

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Hepatitis C virus antibody (anti-HCV) was examined among 540 chronic hemodialysis (HD) patients and 50 predialysis renal failure patients in Fukuoka, Japan. The anti-HCV positive rate was significantly greater in HD patients with a history of blood transfusion than those without it regardless of sexes (males : 37.9% vs 15.8%, p<0.01 and females : 32.3% vs 4.5%, p<0.01) as we reported previously. The result confirmed that blood transfusion is a major route of HCV infection. However, the risk of HCV infection among nontransfused HD patients was still 5.08 times higher compared to blood donors (p<0.001) after adjusting age and sex. On the other hand, anti-HCV positive rate among predialysis renal failure patients was lower than the rate among nontransfused HD patients (2.0% vs 11.8%, p<0.05) and was not different from that among blood donors (O/E=0.63, NS). In addition, anti-HCV positive rate increased with the duration of HD treatment regardless of sex or a history of blood transfusion. These results suggest that renal failure itself does not seem to increase the risk of HCV infection. J Epidemiol, 1993; 3 : 7-10.

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In order to learn the relationship between the population size of municipalities and conduct-ing methods of gastric cancer screening programs according to the Health and Medical Service for the Aged Act of 1982 in Japan, the programs of 2, 795 municipalities having replied a questionnaire survey were analyzed. Several aspects of conducting the programs, such as whether to conduct individual screenings, how to conduct outside office hour screening, how to provide information about screening schedules, keeping and controlling systems of the results, and participation rates, depended on the population size. The difference according to the population size seemed due to differences of life style and social environment between rural and urban, and population size itself. Moreover, the population size should be considered as a confounding factor in analyzing the relationship between the gastric cancer screening program system and the participation rate. J Epidemiol, 1993; 3 : 11-18.

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Seven hundred and fifty four Japanese SLE patients were subdivided into the following 3 groups according to the year of diagnosis : Group A ; 85 cases between 1955 and 1969, Group B ; 322 cases between 1970 and 1979 and Group C ; 347 cases between 1980 and 1990. The clinical features and prognosis were compared among the 3 groups. The number of SLE patients with persistent and/or profuse proteinuria, psychosis, unconsciousness, thrombocytopenia and other disorders in Group C was less than that of Groups A and/or B. The number of cases treated with steroids, immunosuppressants, non-steroidal antiinflammatory drugs, antihypertensive drugs in Group C was less than that of Groups A and/or B. However, the number of cases treated with pulse therapy and plasmapheresis in Group C was more than that of Groups A and/or B. The mortality rate of SLE, especially due to uremia, significantly decreased from Group A to Group C. Five-year and 10-year survival rates in Group C were 95.2% and 93.4%, respectively, revealing a significantly more favorable prognosis than that of the other groups. J Epidemiol, 1993; 3:19-27.

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A matched case-control study on sudden unexpected death, defined as a natural death within 24 hours after the onset of acute symptoms occurring in apparently healthy workers, was carried out. The purpose of our study is to analyze the factors that precede sudden unexpected death among Japanese workers, controlling for differences in working conditions. 102 male cases and 202 age-and sex-matched coworker controls were studied, using questionnaires sent to fulltime occupational health physicians. Mean values of blood pressure, number of cigarettes smoked daily were significantly higher and that of HDL-cholesterol were significantly lower in the sudden death cases than in the controls. A larger number of workers with hypertension and electrocardiogram abnormality and a smaller number of managerial workers and individuals with higher education were found among the sudden death cases than among the controls. Conditional logistic regression analysis suggested that hypertension may be the most positive predictor of sudden unexpected death among Japanese workers (relative risk= 2.37, 95% confidence interval : 1.29-4.35). J Epidemiol, 1993; 3 : 29-34.

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The suggested association between atrophic gastritis as a precursor lesion and subsequent high risk of gastric cancer was examined at the population level in a cross-sectional study of men 40 to 49 years of age in 5 populations with different gastric cancer mortalities. Subjects toltalled 634 men, randomly selected from each population of about 100, 000, whose atrophic gastritis was diagnosed serologically based on a combination of the serum pepsinogen I (PG I) level <70 ng/ml and pepsinogen I/pepsinogen 11 (PG I/PG II) ratio<3.0. The number of atrophic gastritis cases discriminated was 121 among 624 evaluated men (19.4% overall) and its prevalence rates in 5 areas (range : 9.4-26.8%) correlated almost perfectly (r=0.999, p<0.0001) with age-adjusted mortality rates averaged for 1985-89 for gastric cancer (range : 17.3-49.1 per 100, 000). Although some misclassifications could not be denied, especially in discriminating mild/moderate cases, which were separated from severe ones diagnosed more definitively under stricter criteria of PG I< 30 ng/ml and PG I/PG II ratio<2.0, it was unlikely that they affected the above correlation significantly, since a similar good correlation was observed even when a criterion of PG I/PG II ratio<2.5 alone, for which high specificity and sensitivity are known, was applied. Thus, the strong correlation found in the present study not only suggests that the number of middle-aged men with atrophic gastritis may be a basis on which gastric cancer mortality in an area can be determined almost exclusively but also that the serologiccal diagnosis is useful in screening of a group of high risk for gastric cancer. Therefore, this diagnostic method provides a practical method of gastric cancer prevention, although a combination with other methods to diagnose particularly mild/moderate atrophic gastritis is recommended for following-up the high-risk group on an individual basis. J Epidemiol, 1993; 3 : 35-39.

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From 1988-91 we surveyed the prevalence of hepatitis C virus (HCV) infection among the general population of Japanese individuals living in Fukuoka and Okinawa, Japan. The combined antibody to c100-3 protein (anti-c100) and the antibody to GOR epitope (anti-GOR) were used. Persons with HCV infection had anti-c100 and/or anti-c100 in their sera. The overall rate of HCV infection was 3.7% of 2, 835 persons in Fukuoka, a rate significantly higher than the 0.7% of 1, 789 in Okinawa (p<0.001). There was no association between gender and prevalence. In Fukuoka, the prevalence of HCV infection increased with age, from 0.6% in the 0-9 age group to 11.5% in those over 70 years of age. In the over 50 age group, episodes of blood transfusion (18.6%) and surgery (56.7%) in the general population of Fukuoka were more frequent than those (7.0%, 38.6%, respectively) of Okinawa (p<0.001). Moreover, the blood for transfusion in Fukuoka was supplied by paid donors at commercial blood banks from 1953 to 1969, but in Okinawa was supplied by relatives and friends. These results suggest that the difference in prevalence of HCV infection between Fukuoka and Okinawa may be due to episodes of medical treatments and that blood for transfusion from paid donors played an important role in HCV infection. J Epidemiol, 1993; 3 : 41-45.

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