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Study Title and Description

Effect of coffee on endothelial function in healthy subjects: the role of caffeine.



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 Effect of coffee on endothelial function in healthy subjects: the role of caffeine.
Author CM Papamichael,KA Aznaouridis,EN Karatzis,KN Karatzi,KS Stamatelopoulos,G Vamvakou,JP Lekakis,ME Mavrikakis,
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)? In the present randomized placebo-controlled cross-over study, we sought to investigate whether caffeine affects endothelial function in apparently healthy individuals.
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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 We studied 17 healthy young adults (mean age, 28.9 years; range, 25–38; nine men), who were recruited among the personnel of our hospital. All volunteerswere regular, but non-heavy, coffee consumers (they used to drink at least one, but no more than two cups, of coffee daily), nonsmokers and had a body mass index <30 kg/m2. None had a history of arterial hypertension, diabetes mellitus or hypercholesterolaemia, or was on vasoactivemedications or vitamin supplementation. All female participants excluded use of birth-control pills and were examined during the follicular phase of menstrual cycle. Each study day was preceded by a 12–24 h period of abstinence from coffee, tea, cola, alcohol and flavonoid-containing beverages. Study Design: Assessment of Endothelial Function The study was carried out using a randomized single-blind (operator) placebo-controlled cross-over design. All participants were examined in the morning on two separate days in a quiet temperature-controlled room after an overnight fast. During the first study day, after a rest period of 15 min, endothelial function was estimated by the endothelium-dependent FMD (flow-mediated dilatation) of the right brachial artery. A high-resolution linear array ultrasonic transducer (128 XP; Acuson, Mountain View, CA, U.S.A.) was used. The volunteers were then randomized to either drink a cup of freshly brewed caffeine-containing instant coffee (80 mg of caffeine), followed by drinking 200 ml of water, or the corresponding decaffeinated beverage (<2 mg caffeine), which was used as a control for caffeine, and 200 ml of water. Resting and hyperaemic arterial scans were obtained 30, 60, 90 and 120 min after intake. After 2 days, all participants returned and FMD was estimated after ingestion of the opposite kind of beverage, according to the same schedule. Recorded scans were analysed by two independent observers, who were unaware of the study design and status of coffee drinking. FMD was calculated according to the equation: FMD (%) = [(hyperaemic diameter − resting diameter)/resting diameter] x 100. Systolic and diastolic BP were measured at the left brachial artery by using a mercury sphygmomanometer. Measurements were obtained 6–8 min before each brachial artery scan. Statistical Analysis Data are expressed as means +/− S.D. All variables were tested for homogeneity of variance and normal distribution using the Kolmogorov–Smirnov criterion before any statistical analysis was applied. Baseline parameters between the two sessions were compared using Student’s t test for paired measures. In order to evaluate the composite effect of the type of coffee consumed over time on the parameters of interest, an overall 5 x 2 ANOVA for repeated measures was performed [five periods (baseline, 30, 60, 90 and 120 min) x two types of beverage (caffeinated versus decaffeinated coffee)]. ANOVA for repeated measures was also performed in order to detect significant changes in variables over time within the two sessions separately. When a significant interaction occurred, the location of pairwise differences was determined by using the Bonferroni post-hoc test. A P value <0.05 was considered statistically significant.
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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) Blood pressure (SBP and DBP)
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List additional health endpoints (separately). 2 Heart rate
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List additional health endpoints (separately).3 Endothelial function (flow-mediated dilatation [FMD])
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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 Physiological
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What is the study design? Controlled Trial
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Randomized or Non-Randomized? RCT
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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 Systolic and diastolic BP were measured at the left brachial artery by using a mercury sphygmomanometer. A high-resolution linear array ultrasonic transducer (128 XP; Acuson, Mountain View, CA, U.S.A.) was used to estimate FMD
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Caffeine (general) 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? Measured
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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.) Subjects served as their own controls (placebo and baseline)
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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) None
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What conflicts of interest were reported? No information provided
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Refid 15799717
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What were the sources of funding? No information provided
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Results & Comparisons

No Results found.