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Study Title and Description

Coffee, green tea, black tea and oolong tea consumption and risk of mortality from cardiovascular disease in Japanese men and women.



Key Questions Addressed
1 For [population], is caffeine intake above [exposure dose], compared to intakes [exposure dose] or less, associated with adverse effects on cardiovascular outcomes?
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Primary Publication Information
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TitleData
Title Coffee, green tea, black tea and oolong tea consumption and risk of mortality from cardiovascular disease in Japanese men and women.
Author Y Mineharu,A Koizumi,Y Wada,H Iso,Y Watanabe,C Date,A Yamamoto,S Kikuchi,Y Inaba,H Toyoshima,T Kondo,A Tamakoshi, ,
Country
Year 2011
Numbers

Secondary Publication Information
There are currently no secondary publications defined for this study.


Extraction Form: Cardiovascular Design
Design Details
Question... Follow Up Answer Follow-up Answer
What outcome is being evaluated in this paper? Cardiovascular
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What is the objective of the study (as reported by the authors)? The purpose of the present study was thus to examine comprehensively the relationship of the consumption of coffee, green, black and oolong tea with mortality from CVD among Japanese men and women in a large prospective cohort study with 1,010,787 person-years of follow-up. We also examined whether caffeine can be used to explain the effects of these beverages.
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Provide a general description of the methods as reported by the authors. Information should be extracted based on relevance to the SR (i.e., caffeine related methods) Study population: The Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC Study) started between 1988 and 1990. The study consisted of 110,792 individuals (46,465 men and 64,327 women) who were 40-79 years of age and living in 45 communities across Japan. Among them, data on the consumption of all beverages (coffee, green tea, black tea and oolong tea) were available for 36,332 men and 50,925 women. A total of 1,977 men and 2,615 women was then excluded from the study because of a history of stroke, CHD, or cancer at baseline. Therefore, 34,345 men and 48,310 women were involved in the present study. Assessment of cardiovascular disease: For mortality surveillance in each community, investigators conducted a systematic review for death certificates, all of which were forwarded to the public health centre in the area of residency. Mortality data were sent centrally to the Ministry of Health and Welfare, and the underlying causes of death were coded according to the International Classification of Diseases, 9th revision, from 1988 to 1994 and the 10th revision from 1995 to 2003 for the National Vital Statistics. In Japan, registration of death is required by the Family Registration Law and is believed to be followed across Japan. Therefore, all deaths that occurred in the cohort were ascertained by death certificates from a public health centre, except for subjects who died after they had moved from their original community, in which case subjects were treated as censored cases. The follow-up was conducted until the end of 2003, and the average follow-up for the participants was 13.1 years. Cause specific mortality was determined by total CVD (International Classification of Disease, 9th revision codes 390-459, 10th revision codes I01-I99), total CHD (codes 410-414 and I20-I25) and total stroke (430-438 and I60-I69), separately. Assessment of consumption of coffee and caffeine intake: a self-administered dietary questionnaire as described previously. Briefly, participants were asked to state their average consumption of coffee, green, black and oolong teas during the previous year. They could select any of four frequency responses: ‘less than once a week’, ‘about one to two times a week’, ‘about three to four times a week’ and ‘almost every day’. Participants who selected the response of ‘almost every day’ were also asked to state their average consumption of these beverages in numbers of cups per day. The consumption of decaffeinated coffee or tea was not recorded because these products were not commercially available in Japan in the early 1990s. The estimated caffeine content was 153 mg per cup (170 ml) of coffee, 30 mg per cup (200 ml) of green tea, 51 mg per cup (170 ml) of black tea and 38 mg per cup (190 ml) of oolong tea. The mean caffeine intake was 287 mg/day for men and 254 mg/day for women. Relative proportions of caffeine intake by beverage were 45-49% from coffee, 47-48% from green tea, 1-2% from black tea and 3-6% from oolong tea. The reproducibility and validity of this dietary questionnaire was reported previously.
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How many outcome-specific endpoints are evaluated? 3
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What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately) Total cardiovascular disease mortality
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List additional health endpoints (separately). 2 Coronary heart disease mortality
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List additional health endpoints (separately).3 Stroke mortality
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List additional health endpoints (separately).4
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List additional health endpoints (separately).5
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List additional health endpoints (separately).6
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Clinical, physiological, other Clinical
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What is the study design? Cohort
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Randomized or Non-Randomized?
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What were the diagnostics or methods used to measure the outcome? Objective
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Optional: Name of Method or short description For mortality surveillance in each community, investigators conducted a systematic review for death certificates, all of which were forwarded to the public health centre in the area of residency. Mortality data were sent centrally to the Ministry of Health and Welfare, and the underlying causes of death were coded according to the International Classification of Diseases, 9th revision, from 1988 to 1994 and the 10th revision from 1995 to 2003 for the National Vital Statistics. In Japan, registration of death is required by the Family Registration Law and is believed to be followed across Japan. Therefore, all deaths that occurred in the cohort were ascertained by death certificates from a public health centre, except for subjects who died after they had moved from their original community, in which case subjects were treated as censored cases. The follow-up was conducted until the end of 2003, and the average follow-up for the participants was 13.1 years. Cause specific mortality was determined by total CVD (International Classification of Disease, 9th revision codes 390-459, 10th revision codes I01-I99), total CHD (codes 410-414 and I20-I25) and total stroke (430-438 and I60-I69), separately.
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Caffeine (general)
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Coffee, Chocolate, energy drink, gum, medicine/supplement, soda, tea, other? Coffee, tea
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Measured or self reported? Self-report
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Children, adolescents, adults, or pregnant included? Adults
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What was the reference, comparison, or control group(s)? (e.g. high vs low consumption, number of cups, etc.) For coffee and green tea, < 1 cup/week was the low group.
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What were the listed confounders or modifying factors as stated by the authors? (e.g. multi-variable components of models.  Copy from methods) We presented baseline characteristics according to the frequency of consumption of each beverage. Tests for trends were conducted using the median values of confounding variables in each category of beverage. The linear regression model was used for continuous variables and the logistic regression model was used for categorical variables. The HR and 95% CI for CVD were calculated in each category of beverage and in each quartile of caffeine intake; less than one cup per week or the lowest quartile was used as the reference category. We estimated age and body mass index (BMI)-adjusted HR and multivariable HR using the Cox proportional hazards model, adjusting for age (in years), sex-specific quintiles of BMI (weight in kilograms divided by the square of height in meters), smoking status (never, former, or current (one to 19, 20-29, or >/- 30 cigarettes/day)), alcohol intake (never, former, or current (one to 22, 23-45, 46-68, or >/=69 g/day)), hours of walking (<0.5, 0.5, 0.6-0.9 and >/= 1.0 h/day), hours of participation in sports (<1, 1-2, 3-4 and >/= 5 h/week), use of hormone therapy for women, history of hypertension (yes or no), history of diabetes mellitus (yes or no), perceived mental stress (low, medium and high), and educational level (primary school, junior high school, high school and college or higher). Furthermore, we adjusted for the consumption of other beverages, multivitamin use, vitamin E supplement use, consumption of total fruits, total vegetables, total bean products, total meats (continuous variable, servings/week for each food) and daily total energy intake (continuous variable, kcal/day). Sex-specific quintiles of BMI were used to account for different distributions between the sexes. We conducted a test for trend by treating median values of each category of beverage or caffeine intake as continuous variables. We also examined a possible non-linear relationship between mortality from total CVD and caffeine intake, coffee consumption or green tea consumption with cubic spline analysis using SAS macro. We examined the association of each beverage consumption and total caffeine intake with the risk for CVD stratified by age group (40-59 years and 60-80 years), smoking status (non or ex-smokers and current smokers), alcohol intake (non or ex-drinkers and current drinkers), history of hypertension (yes and no), history of diabetes (yes and no), BMI (<25.1 kg/m2 and >/= 25.1 kg/m2), educational level (before college and college or higher), total fruit intake (<3 servings/week and >/= 3 servings/week), total vegetable intake (<3 servings/week and >/= 3 servings/week) and total bean intake (<3 servings/week and >/= 3 servings/week). The interactions with these stratified variables were tested by using cross-product terms of caffeine intake and the stratified variables.
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What conflicts of interest were reported? There were no competing interests.
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Refid 19996359
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What were the sources of funding? Grants-in-Aid for Scientific Research from the Ministry of Education, Science, Sports and Culture of Japan (nos 61010076, 62010074, 63010074, 1010068, 2151065, 3151064, 4151063, 5151069, 6279102 and 11181101).
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Results & Comparisons

No Results found.