BACKGROUND: The 5th edition of the Japanese food composition table enables us to evaluate intakes of folate and vitamins B₆ and B₁₂, which are associated with risk of chronic diseases.
METHODS: We investigated long-term trends in dietary intake of those nutrients in two rural communities; Ikawa from1974 through 2000, and Kyowa from 1982 through 2001. The 24-hour recall method was adopted. Intake of green tea interviewed from 1994 was used to examine food sources for these nutrients in the latest period, but not to evaluate long-term trends. Reduced intakes of nutrients due to cooking were not taken into account.
RESULTS: Age-adjusted mean folate intake increased by 30% in Ikawa between the 1970's and 1980's, and then leveled off to the latest survey, while that in Kyowa did not change throughout the survey periods. The increased folate intake was primarily due to green/yellow vegetables. Mean vitamin B₆ intake did not change except that it increased for Ikawa women in the 1980's and decreased for Kyowa men in the latest period. No secular trend was found for mean vitamin B₁₂ intake. The largest source for folate intake was total vegetables (38-58% of total intake) and the second largest source was alcohol/beverages including green tea (11-24%). Fish/shellfish was the largest source for vitamins B₆ (16-23%) and B₁₂(77-84%).
CONCLUSIONS: Dietary intakes of folate, vitamins B₆ and B₁₂ showed no notable long-term trend, except for an increased folate intake between the 1970's and 1980's due to an increased intake of green/yellow vegetables.
J Epidemiol2005;15:29-37.

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BACKGROUND: Physicians' perception and attitudes towards a research topic and trial management could influence their participation in a randomized controlled trial. The objectives of this study were to determine the reasons for physicians' participation in and attitudes towards the Candesartan Antihypertensive Survival Evaluation in Japan (CASE-J) trial.
METHODS: CASE-J's main objective is to compare the effectiveness of an angiotensin II receptor antagonist (candesartan cilexetil) with that of a calcium channel blocker (amlodipine besilate) in terms of the incidence of cardiovascular events among high-risk hypertensive patients. We conducted a questionnaire survey among the physicians (n=512) participating in that trial to determine the reasons behind their participation and to elicit their reactions to the trial management.
RESULTS: Eighty-eight percent of the 512 participating physicians responded to our survey. The main reasons for participation were clear objectives of the trial (85.1%), a simple protocol (61.1%), interest in finding out the inhibiting effects of the drugs on cardiac events (80.2%), and a well-organized support system (59.8%). As for negative factors, case registration and follow-up were considered cumbersome by 28.6% and 10.8%, respectively while 44.2% stated that support by the clinical research coordinators provided by the trial management authority was necessary for case screening, recruitment process, patient registration, and follow-up. Multivariate logistic regression analysis showed that participants who did not use a computer very regularly (odds ratio = 1.9, 95% confidence interval = 1.1-3.6) were more likely to consider the case registration and follow-up procedures as a cumbersome.
CONCLUSION: The information generated by this study could be useful in designing future randomized controlled trials in Japan and abroad.
J Epidemiol2005;15:38-40.

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BACKGROUND: The association between alcohol consumption and risk of hyperuricemia has been pointed out. However, the potential difference in the risk of hyperuricemia according to types of alcoholic beverage has not been assessed.
METHODS: A cross-sectional survey was performed using data from 715 men who had regular medical examinations in their workplace in 2001. Subjects were interviewed using a questionnaire about their lifestyle including types of alcoholic beverages and quantity of alcohol consumed per day. Logistic regression analysis was performed to assess the relationship between the types of alcoholic beverage and high serum uric acid level.
RESULTS: Compared with subjects who did not drink alcohol, the odds ratio (OR) of hyperuricemia (serum uric acid =7.0+ mg/dL) was 2.89 (95% confidence interval [CI]: 1.46-5.71) for subjects who consumed 50+ g/day of ethanol, and 2.64 (95% CI: 1.33-5.24) for subjects who consumed 25-49g/day. Compared with subjects who drank Japanese sake, subjects who drank beer (OR=1.24, 95% CI: 0.55-2.80) or shochu (OR=1.06, 95% CI: 0.44-2.51) did not have a statistically significant difference in risk for hyperuricemia.
CONCLUSION: These findings from a cross-sectional study of Japanese male office workers suggested that alcohol consumption is associated with an increased risk of hyperuricemia and that this increased risk does not vary according to the types of alcoholic beverage.
J Epidemiol2005;15:41-47.

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BACKGROUND: Knowledge of and attitudes toward suicide and depression have not been fully investigated in Japan.
METHODS: Study areas comprised municipalities in northern Japan where standardized mortality ratios (SMRs) from suicide compared with a Japanese standard ranged from 1.62 to 3.72 in men and from 1.43 to 3.49 in women. We conducted a questionnaire survey on a random sample of 7,136 participants aged 20 to 79 years, and analyzed data of 5,547 (77.7%) subjects. We categorized seven municipalities, from which the subjects were drawn, into three groups according to the SMR from suicide. Self-Rating Depression Scale (SDS) score was used for evaluation of depressive states.
RESULTS: The SDS score was significantly higher in the high SMR group in women, but no significant difference among the three SMR groups was observed in men. The percentage of subjects with nine years or less of education was significantly higher in the high SMR group both in men and in women. The percentage of men who drank alcohol once a week or more was significantly higher in the high SMR group. The percentages of subjects unaware that depressive states are treatable by medication were not significantly different among the three SMR groups both in men and in women, while the percentage of men unwilling to see a psychiatrist when depressed was the lowest in the high SMR group.
CONCLUSION: Although a significant difference in SDS score was observed in women, most of the psychosocial factors or knowledge of and attitudes toward suicide and depression were not adversely associated with SMR group.
J Epidemiol2005;15:48-55.

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BACKGROUND: Few studies have examined the validity of administering tuberculosis control measures based on tuberculin skin test (TST) erythema measurement. The present study aimed to clarify the relationship between the erythema and the induration seen following TST and to evaluate the validity of diagnosing tuberculosis infection based on the erythema following TST in school-aged contacts who had been vaccinated with bacillus Calmette-Guérin (BCG) in infancy.
METHODS: A 56-month longitudinal study from January 1999 through September 2003 followed 566 junior high school students in Kochi City who were contacts of an infectious tuberculosis case. To evaluate the diagnostic accuracy of the erythema and induration following TST of the contacts, false-positive and false-negative TST results were noted.
RESULTS: The natural logarithm of the erythematous response size was linearly related to the induration size. When the size of the erythematous response was used to determine the presence of tuberculosis infection, the proportion of infected children increased with increasing exposure to the index case. When the TST results in the contact investigation were interpreted together with the change in the size of the erythematous response from that observed at the regular school-entry checkup, false positive test results were avoidable among the students who had a large erythematous response after the contact investigation TST, but whose response was only slightly larger than their erythematous response following the school-entry TST. Among the students whose TST results were negative, 1.9% developed tuberculosis.
CONCLUSION: Both erythema and induration measurement were equally effective for identifying tuberculosis infection in schoolchildren vaccinated with BCG.
J Epidemiol2005;15:56-64.

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