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Study Title and Description

Caffeine and risk of atrial fibrillation or flutter: the Danish Diet, Cancer, and Health Study.



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 Caffeine and risk of atrial fibrillation or flutter: the Danish Diet, Cancer, and Health Study.
Author L Frost,P Vestergaard,
Country
Year 2005
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 current study was to examine the association between the amount of caffeine consumed per day, and the risk of atrial fibrillation or flutter in the Danish Diet, Cancer, and Health Study.
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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 Danish Diet, Cancer, and Health study is a prospective cohort study primarily focused on the role of diet in cancer risk, but which has the potential for studying other diseases as well. From December 1993 through May 1997, subjects aged 50–64 y (n=80,996 M, 79,729 F) were invited to participate in the study; 27,177 men and 29,876 women accepted the invitation. Eligible cohort members were born in Denmark, were living in the Copenhagen and Aarhus areas, and had no previous cancer diagnosis in the Danish Cancer Registry. To study incident cases of atrial fibrillation and to reduce confounding, we excluded participants who had been hospitalized before baseline evaluation with endocrine diseases or cardiovascular diseases others than hypertension, as recorded in the National Registry of Patients. Baseline Data Height, weight, systolic and diastolic blood pressures, and total serum cholesterol were measured at baseline. Body weight was measured with the use of a digital scale (Soehnle-Waagen, Murrhardt, Germany) and was recorded to the nearest 100 g. Systolic and diastolic blood pressures were measured by using an automatic blood pressure measurement device (Takeda UH 751, Tokyo). Nonfasting total serum cholesterol was measured according to national guidelines. Measurement of Caffeine Consumption All cohort members completed a detailed, semiquantitative [previously validated] food-frequency questionnaire (FFQ). The daily intake of specific foods and nutrients was calculated from the FFQ for each participant with the use of FOODCALC software (version 1.3; J Lauritsen, University of Copenhagen). Standard recipes and sex-specific portion sizes were applied to calculate intake in grams per day (g/d) by using data from different sources—i.e., the 1995 Danish National Dietary Survey, 24-h diet recall interviews from 3818 of the study participants, and various cook books. We summed the daily intake of caffeine from coffee, tea, cola, cocoa, and chocolate for each subject. Atrial Fibrillation and Atrial Flutter We identified probable cases of atrial fibrillation or flutter within the cohort in The Danish National Registry of Patients—ie, cases through 31 December 2001 with the discharge diagnoses 427.93, 427.94, and I48. Follow-up The study participants were followed in the National Registry of Patients and in the Danish Civil Registration System. Linking was done by use of the civil registry number. Follow-up for atrial fibrillation or flutter began on the date of visit to one of the study centers and ended on the date of an event or a censoring (ie, a diagnosis of atrial fibrillation or flutter, death, emigration, or 31 December 2001, whichever came first). Statistical Analysis We used piecewise linear regression to examine the relation between a continuous variable and the hazard of atrial fibrillation or flutter. We retained the continuous variable as continuous in the Cox regression model, when appropriate, according to these analyses. The variables included in our final models in men and women were the quintile of caffeine consumption, age (y), sex, body height (cm), BMI, systolic blood pressure (mm Hg), treatment for hypertension (no or yes), total serum cholesterol >6 mmol/L (no or yes), and alcohol consumption (g/d). Thereafter, we assessed further potential confounders: smoking (ie, never, former, or current) and length of education after elementary school was included with 4 categories (i.e., 0 y, <3 y, 3–4 y, and >4 y) to evaluate the potential for changes in the estimate of the hazards for atrial fibrillation or flutter associated with the consumption of caffeine. Correlation was evaluated by Spearman nonparametric correlation analysis. We used a poisson regression analysis to test for trends in incidence rates over quintiles. Tests for linear trend over quintiles were calculated by assigning the medians of intake in quintiles treated as a continuous variable. The assumption of proportional hazards in the Cox models was evaluated by using graphic assessment and found appropriate in all models. We calculated 95% CIs throughout the analyses. All reported P values are two-sided. We used SPSS statistical software (version 11.5; SPSS Inc, Chicago) and STATA statistical software (version 7; Stata Corp, College Station, TX).
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How many outcome-specific endpoints are evaluated? 1
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What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately) Atrial fibrillation/flutter
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List additional health endpoints (separately). 2
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List additional health endpoints (separately).3
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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 Measured with an instrument or from National Registry
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Caffeine (general) Caffeine (general)
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Coffee, Chocolate, energy drink, gum, medicine/supplement, soda, tea, other? Coffee, Chocolate, soda, 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.) Lowest quintile (mean of 248 +/- mg/day)
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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) age (y), sex, body height (cm), BMI, systolic blood pressure (mm Hg), treatment for hypertension (no or yes), total serum cholesterol >6 mmol/L (no or yes), and alcohol consumption (g/d).
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What conflicts of interest were reported? No information provided
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Refid 15755825
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What were the sources of funding? Supported by a senior research fellowship from the Danish Medical Research Council (grant no. 22-02-0582; to LF).
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Results & Comparisons

No Results found.