In Japan recently there has been a rapid change in living and eating patterns along with accelerated urbanizations in rural communities. This provides an unique opportunity to observe a critical "natural experiment" of change in both risk factors and disease. Data on blood pressures and time trends were obtained in population-based surveys conducted in rural Japan ; the first survey from 1963-66, the second from 1972-75, and the third from 1980-83. This report describes the population trends over 20 years for blood pressure distributions and its related factors. Between the 1960s and the 1970s, the prevalence of a higher blood pressure level declined although no remarkable shift of the blood pressure distribution was observed. However, between the 1970s and the 1980s, there was a significant downward shift of the blood pressure distribution. The decline in blood pressure between the 1960s and 1970s was primarily related to a fall in the prevalence of elevated blood pressure, attributable in turn to the greater use of anti-hypertensive medications and improved blood pressure control. In contrast, the large downward shift in the whole blood pressure destributions between the 1970s and the 1980s was attributable partly to improved hypertension control and apparently also to changes in environmental factors of associated behaviors that affected the whole distribution. The correlation between blood pressure and relative weight index was weak in the 1960s but became stronger in the 1970s and the 1980s. The significant blood pressure trend in a whole population are consistent with the reported decline in stroke incidence in this population. J Epidemiol, 1993; 3 : 63-70.
The subjects were 13, 500 employees. Sera and information on age, sex, subjective symptoms in the stomach and past histories of peptic ulcer were collected. Serum pepsinogen I and II values were measured and analyzed (LPI and LPII : natural logarithm of serum pepsinogen I and II (ng/ml) respectively). Among those with stomach ache, heavy feeling of stomach or nausea, LPI and LPII levels were higher than among those without the symptoms, and it was suggested that those with subjective stomach symptoms should be dealt with separately in the evaluation of efficacy of gastric cancer mass-screening by serum pepsinogen values. Among those with a past history of duodenal ulcer, LPI and LPII levels were higher, and among those with a past history of gastric ulcer, LPI level was lower but LPII level was higher, and it was suggested that those with a past history of peptic ulcer should also be dealt with separately in the evaluation. Because serum pepsinogen values changed depending on age and sex among those without any subjective stomach symptoms or past history of peptic ulcer, it was suggested that the evaluation of efficacy of these values for mass-screening should be done separately with respect to age and sex. J Epidemiol, 1993; 3 : 71-76
Major source of NaCl among Japanese diet were quantified. Adult inhabitants (1334 subjects, or 499 men and 835 women at the ages of 20 to 70 years) in 49 regions (mostly agricultural) all over Japan offered 24-hour total food duplicates in winter seasons. Sodium chloride (NaCl) contents in each food items in the duplicates were estimated by the weight taking advantage of the Standard Tables of Food Compositions with assumption that sodium is totally attributable to NaCl. The NaCl contents in the duplicates distributed essentially normally with a mean of 14.4 g and a standard deviation of 6.1 g. High NaCl intake was associated with the consumption of pulses, fish/shellfish and vegetables in addtion to seasoning/spices. Further analysis showed that miso paste, soy bean sauce and pickles accounted for 23.6, 18.8 and 16.7% of total NaCl intake, respectively, or almost 60% when the three items are combined. Multiple regression analysis also indicated that miso paste has the strongest influence on total NaCl intake. Of particular interest was the fact that consumption of pickles increased markerdly as a function of higher salt intake, from 0.1 g (in terms of NaCl content) among low NaCl consumers (taking <5 g NaCl/day) to 7.0 g among high NaCl consumers (with*30 g NaCl/ day). J Epidemiol, 1993; 3 : 77-82.
To investigate the age-associated changes in physical and mental functions, epidemiological surveys were conducted for a random sample (N=3, 704) of residents aged 65 years and over in Sendai City, Japan, in 1988 and 1991. The frequency of dementia was derived from the epidemiological surveys. The prevalence of dementia aged 65 years and over in 1988 was 5.13 per 100 persons with age-specific rates of 0.78, 1.89, 6.02, 11.95 and 26.31 per 100 persons for the age groups 65-69, 70-74, 75-79, 80-84, and 85+, respectively. The incidence during 1988-1991 was 1.74 per 100 person-years with age-specific rates of 0.73, 0.87, 2.29, 3.62, and 8.48 per 100 person-years, respectively. Using the Japan population in 1985, the agestandardized rates for females were higher than those for males for both prevalence and incidence. The prevalence in this study was consistent with those of other population-based studies in urban Japan. There are few studies of the incidence of dementia in Japan, and this is the first such study based on a longitudinal design in an urban area of Japan. J Epidemiol, 1993; 3 : 83-89.
To explore reproductive risk factors for asymptomatic gallstones in females, we conducted a nested case-control study. The study comprised 126 cases (women with asymptomatic gallstones) and 378 controls ( women free from gallstones and other diseases of the liver and biliary tract) among 3, 927 women aged 40 years or more in Y town, Hokkaido, Japan. Controls were randomly selected with an allocation ratio of 1 : 3 from 3, 599 cohort women, matching to cases for sex(female), age (2 years), residential area, and year of examination. Odds ratio analysis revealed the following major findings. (1) Women married for the first time at 22 years old or later are likely to be at greater risk of asymptomatic gallstones with odds ratios of 1.60 (95% confidence interval : 0.97-2.64) ; 1.68 (0.96-2.94) for postmenopausal women. (2) First full-term delivery at 23 years old or later tended to increase the risk by 1.63 (0.97-2.77) ; 1.63 (0.90-2.9) when postmenopausal. and (3) Pregnancy of 5 times or more also appeared to elevate the risk by 1.47 (0.97-2.22) ; 1.55 (0.94-2.57) when postmenopausal. Two odds ratios obtained by logistic regression analysis are significant: 1.67 (1.14-3.32) and 1.59 (1.01-2.52) for age at first marriage and total number of pregnancy, respectively. Finally, we emphasize that this is the first epidemiological investigation in Japan which explored an association between reproductive episodes and asymptomatic gallstone formation in women. J Epidemiol, 1993; 3 : 91-97.
To examine an association between serum cholesterol level and cancer mortality, a nested case-control study was conducted among 5, 796 civil service workers in Japan who underwent periodic health examination. One-hundred and thirty-one deaths (cases), including 73 cancer deaths, were identified in the study period from 1980/1981 to September 1, 1991. Two controls were randomly selected for each case, matched for age, sex, year of examination and job status. As a major result, an increase in serum cholesterol of 10 mg/dl significantly reduced cancer risk by 0.91 times in men, but not in women. This reduction of cancer risk in men was found not to be confounded by body mass index (BMI), smoking habits, and drinking habits. No significant association could be found between serum cholesterol level and specific sites of cancer. Separate analysis by follow-up period significantly revealed an inverse association between serum cholesterol and cancer deaths in men in 6 years or later after serum measurement. This inverse association was believed not to be ascribable to an effect of a preclinical cancer. J Epidemiol, 1993; 3 : 99-107.
A model was developed to account for the age distribution of colorectal cancer (CC) incidence among familial adenomatous polyposis (FAP) and in the general population. Estimated cumulative incidence rate of CC among 1050 FAP patients was 25% at age 33, 50% at age 41 and 75% at age 50. In the general population, estimated cumulative incidence rate of CC was 0.8% at age 60, 11.9% at age 70 and 3.7% at age 80. We modeled a hypothesis that a cancer cell starts clonal expansion when a certain number of independent rate-limiting mutations is accumulated, and the clone is clinically detected after a relatively long duration of progression. Using expression, 1-(1-(1-exp(-m.age))P)N for mutation accumulation and a lognormal progression duration with median 9 years for clinical detection, we could produce the age distribution for FAP patients, when m (mutation rate)=6/105 cells per year, p (number of mutations)-3 and N (number of stem cells)=108. The model fitted in the general population if p=4, with other parameters unchanged. Our results suggests that a number of rate-limiting processes in CC carcinogenesis is 3 for FAP and 4 for the general population and the difference is a single mutation. J Epidemiol, 1993; 3 : 109-115.
From April 1991 to March 1992, there were 117 elderly persons whose materials were examined for a bacterial culture in various clinical aspects. They consisted of 74 inpatients and 23 outpatients in a geriatric hospital, and 20 residents of a nursing home. The retrospective study was carried out in order to evaluate the various factors which may influence the occurence of methicillin-resistant Staphylococcus aureus (MRSA) infection in the elderly. The positive rate of MRSA was significantly greater for the inpatients (27.0%) than for the outpatients (0.0%) and the residents of a nursing home (5.0%). Compared to the MRSA negative inpatients, the MRSA positive inpatients had a lower ADL score (0.3*0.7 vs 1.4*1.2, p<0.05) and a larger amount of antibiotics prior to the bacterial culture (1.8*1.4 vs 0.8*1.3, p<0.05). After controlling for the confounding effects of age, length of hospitalization, ADL score and the administration of antibiotics, the risk of MRSA infection among the inpatients was increased in patients who could not either take meals, walk or use restroom by themselves (OR 2.24, 95% Cl 1.22-4.10) and in patients undergoing antibiotic therapy (OR 1.88, 95% Cl 1.03-3.44). In the elderly population, the disability to perform ADL seems to be one of the most important risk factor for MRSA infection. J Epidemiol, 1993; 3 : 117-120.
A hospital based case-control study was carried out to assess the association of Hepatitis B surface antigen (HBsAg), past history of blood transfusion, and alcohol consumption with the development of liver cirrhosis between April 1986 and June 1989. During the study period, 215 liver cirrhosis outpatients (125 males and 90 females) were identified in Kurume University Hospital. Each case was matched with one control (1 : 1 matching) on age, sex, and residence who was the patient admitted to either of two affiliated general hospital in Kurume City. Odds ratios of 4.25 (95% CI : 1.18-15.27) for male and 10.18 (95% Cl : 1.35-76.64) for female after controlling for other factors indicated that HBsAg positive seemed to have a significant contribution to the development of liver cirrhosis for both sexes. Cases had a tendency to have a higher proportion of past history of blood transfusion than controls for both sexes. In particular, significant increase in odds ratio was noticed with increasing years elapsed from the first blood transfusion for female (OR=0.97, 7.80, 14.61 for 0-9 yrs, 10-19 yrs, and 20 yrs+, respectively). No significant association was detected for alcohol drinking. J Epidemiol, 1993; 3 : 121-127.