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Study Title and Description

Coffee consumption and risk of coronary heart disease: a meta-analysis.



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 consumption and risk of coronary heart disease: a meta-analysis.
Author F Sofi,AA Conti,AM Gori,ML Eliana Luisi,A Casini,R Abbate,GF Gensini,
Country
Year 2007
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)? We decided to conduct a systematic review with meta-analysis of the available epidemiological studies, both case-control and prospective, in order to evaluate if habitual coffee consumption is associated with an increased risk of CHD.
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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 Selection We conducted a systematic literature search of MEDLINE from 1966, EMBASE from 1990, Science Citation Index from 1994, and the Cochrane Systematic Review Database up to April 2006, to identify studies that examined the association between habitual coffee consumption and CHD, with an analytical design-either case-control (retrospective or nested) or longitudinal. We used a combined text word and medical subject headings (MeSH) search strategy with the terms ‘coffee’ and ‘caffeine’ in combination with ‘cardiovascular diseases’, ‘coronary artery disease’, ‘coronary heart disease’, ‘myocardial infarction’, and ‘acute coronary syndromes’. We included references listed in the retrieved articles as well as in review articles and in meta-analyses. The aim of this study was to evaluate the possible association between coffee consumption and occurrence of CHD, with non-users or the lowest category as a reference. Hence, to be included in the meta-analysis, studies had to provide, as primary or secondary outcome, the association between coffee and CHD, as well as estimates of associations for the different categories of coffee consumption, and full information on study design and participant characteristics. Our search strategy generated 24 potentially relevant case-control articles. Eleven studies were excluded because they (1) did not contain sufficient information to enable an estimate of risk or its standard error to be calculated for all categories of coffee consumption, did not report outcomes of interest for this meta-analysis, reported only data for decaffeinated coffee consumption, or a study represented the final data from a previous paper, so only the final paper was included. Hence, 13 case-control papers were included in the final analysis, incorporating 9487 cases of CHD and 27,747 controls. With regard to cohort prospective studies, we identified 38 potentially relevant studies, of which only 10 satisfied the inclusion criteria. Data Extraction All data were independently extracted by two investigators (F.S. and A.M.G.) through use of a standardized data extraction tool, and were entered into separate databases. Data regarding study design, participant characteristics, country of origin, adjustment for potential confounders, measurements of coffee consumption, outcomes, and estimates of associations, were sought from each article. Results were compared, and disagreements were resolved by consensus. In cases in which there was more than one published report on the same population or group of patients, the most recent article was selected for analysis. Statistical Analysis Data were analysed by using Review Manager (RevMan) software for Windows (version 4.2) by the Cochrane Collaboration, 2003, and STATA (version 8.2). We distinguished four levels of coffee consumption: the highest category of consumption (mainly > 4 cups per day); the second highest category of coffee consumption (mainly 3-4 cups per day); the third highest category of coffee consumption (mainly </= 2 cups per day); and the reference category (none or < 1 cup per day). Studies not reporting categories of coffee consumption were excluded from each analysis to improve comparability with other studies (three case-control studies from the second highest category and two from the third category, and two cohort prospective studies from the second highest category and one study from the third category). We used the results of the original studies from multivariable models with the most complete adjustment for potential confounders. The analysis was carried out using a random-effects model that accounts for inter-study variation and provides a more conservative estimate than a fixed model. Thus, we calculated random summary odds ratios (OR) and relative risks (RR) with 95% confidence intervals (CI) for case-control and cohort studies, respectively, by using the inverse-variance method. The potential sources of heterogeneity were assessed using the standard chi-square test. In addition, the statistic I2 was used to investigate heterogeneity by examining the extent of inconsistency across the study results. To examine the source of heterogeneity across studies we conducted sensitivity analyses, according to some characteristics of the studies included in the meta-analysis; i.e. the different region of origin of the studies (Europe/USA), the year of publication (studies published before and after the median year of publication of all the studies combined, i.e. 1995), as well as outcome measures (fatal, non-fatal events), and number of years of follow-up within cohort studies (before and after the median years of follow-up of all the studies combined, i.e. 15 years). Funnel plots were performed to assess potential publication bias. Moreover, to estimate whether publication bias (if present) would explain the observed associations, we calculated fail-safe numbers that indicated the number of studies with null results that would need to be added to the meta-analysis in order to reduce the overall level of significance of the observed result to that of non-significance.
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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) Coronary heart disease
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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? Meta-analysis
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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
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Caffeine (general)
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Coffee, Chocolate, energy drink, gum, medicine/supplement, soda, tea, other? Coffee
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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.) Reference group was defined as <1 cup/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) Individual studies included a variety of confounders. Meta analysis relied on each study's results with the most complete adjustment for potential confounders
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What conflicts of interest were reported? No information provided
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Refid 17156982
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What were the sources of funding? This research was submitted to a Call for Research on Coffee and Cardiovascular Diseases and selected for a grant by SINU, (Italian Society of Human Nutrition).
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Results & Comparisons

No Results found.