Advanced Search

Study Preview



Study Title and Description

Cardiovascular effects of caffeine in 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?
  • Comments Comments (
    0
    ) |

Primary Publication Information
  • Comments Comments (
    0
    ) |
TitleData
Title Cardiovascular effects of caffeine in men and women.
Author TR Hartley,WR Lovallo,TL Whitsett,
Country
Year 2004
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
  • Comments Comments (
    0
    ) |
What is the objective of the study (as reported by the authors)? We investigated the vascular versus cardiac effects of caffeine in women at rest and during mental stress.
  • Comments Comments (
    0
    ) |
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) Premenopausal women (n = 42) were compared with age-matched men (n = 35). All were nonobese, in good health by physical examination, normotensive (BPs <135/85 mm Hg), regularly consumed caffeine (50 to 700 mg/day), smoked <6 cigarettes/day, and used no medications with cardiovascular or metabolic effects. Women were not taking oral contraceptives and not pregnant according to pregnancy test (One Step, Inverness Medical Ltd., Beachwood Park, Scotland). Subjects were randomly assigned to receive caffeine (n = 21 women and n = 16 men) or placebo (n = 21 women and n = 19 men) in a double-blind trial. Caffeine (3.3 mg/kg, equivalent to 2 to 3 cups of coffee; USP, Amend Drug and Chemical Co., Irvington, New Jersey) was taken mixed with 6 oz of grapefruit juice (Texsun, Weslaco, Texas). Placebo consisted of grapefruit juice alone. Subjects abstained from caffeine starting at 6:00 P.M. the night before testing. To verify compliance, saliva was collected at the end of baseline. Sessions began at about 8:00 A.M. and lasted 3 hours. The protocol included instrumentation (20 minutes), adaptation (30 minutes), baseline (10 minutes), caffeine or placebo drink (5 minutes), drug absorption (45 minutes), task I (reading or speaking, 6 minutes), recovery (30 minutes), task II (alternate task, 6 minutes), and recovery (30 minutes). All cardiovascular measurements were made as the subject sat semirecumbent in a recliner chair. BP was measured with a Dinamap monitor (Critikon, Tampa, Florida). Stroke volume and systolic time intervals were recorded by an impedance cardiograph (model 304B, Minnesota Impedance Cardiograph, Minneapolis, Minnesota). Impedance signals and electrocardiograms were ensemble averaged and analyzed by proprietary software (Waveshell, Center for Biomedical Engineering, Research Triangle Institute, Research Triangle Park, North Carolina). Cardiovascular variables were systolic BP, diastolic BP, mean arterial pressure, and pulse pressure (systolic BP -diastolic BP); heart rate; stroke volume; cardiac output (stroke volume x heart rate); total peripheral resistance (mean arterial pressure x 80/cardiac output) and a vascular compliance index (stroke volume/pulse pressure). BP was measured every 2 minutes throughout the study. Impedance data were recorded continuously and then averaged for 12 time periods: baseline (10 minutes), caffeine or placebo response (15, 30, and 45 minutes after taking the drug), task I (preparation and task) and recovery periods 1 and 2 (15 minutes each), and task II (preparation and task) and recovery periods 1 and 2 (15 minutes each). Responses to caffeine and the tasks were tested as changes from baseline in the subsequent 11 periods. Baseline activity during the pre-drug period was tested using 2 gender x 2 drug groups analyses of variance (ANOVAs). To characterize gender differences in response to caffeine versus placebo, we performed a multivariate ANOVA on each dependent variable comparing 2 gender x 2 drug groups x 11 periods after taking the drug. Significant main effects or interactions were followed by univariate ANOVAs and specific contrasts as indicated.
  • Comments Comments (
    0
    ) |
How many outcome-specific endpoints are evaluated? 2
  • Comments Comments (
    0
    ) |
What is the (or one of the) endpoint(s) evaluated? (Each endpoint listed separately) Blood pressure (SBP and DBP)
  • Comments Comments (
    0
    ) |
List additional health endpoints (separately). 2 Vascular (arterial) compliance
  • Comments Comments (
    0
    ) |
List additional health endpoints (separately).3
  • Comments Comments (
    0
    ) |
List additional health endpoints (separately).4
  • Comments Comments (
    0
    ) |
List additional health endpoints (separately).5
  • Comments Comments (
    0
    ) |
List additional health endpoints (separately).6
  • Comments Comments (
    0
    ) |
Clinical, physiological, other Physiological
  • Comments Comments (
    0
    ) |
What is the study design? Controlled Trial
  • Comments Comments (
    0
    ) |
Randomized or Non-Randomized? RCT
  • Comments Comments (
    0
    ) |
What were the diagnostics or methods used to measure the outcome? Objective
  • Comments Comments (
    0
    ) |
Optional: Name of Method or short description BP was measured with a Dinamap monitor (Critikon, Tampa, Florida). Stroke volume and systolic time intervals were recorded by an impedance cardiograph (model 304B, Minnesota Impedance Cardiograph, Minneapolis, Minnesota)
  • Comments Comments (
    0
    ) |
Caffeine (general) Caffeine (general)
  • Comments Comments (
    0
    ) |
Coffee, Chocolate, energy drink, gum, medicine/supplement, soda, tea, other?
  • Comments Comments (
    0
    ) |
Measured or self reported? Measured
  • Comments Comments (
    0
    ) |
Children, adolescents, adults, or pregnant included? Adults
  • Comments Comments (
    0
    ) |
What was the reference, comparison, or control group(s)? (e.g. high vs low consumption, number of cups, etc.) Placebo control
  • Comments Comments (
    0
    ) |
What were the listed confounders or modifying factors as stated by the authors? (e.g. multi-variable components of models.  Copy from methods) Gender
  • Comments Comments (
    0
    ) |
What conflicts of interest were reported? No information provided
  • Comments Comments (
    0
    ) |
Refid 15081447
  • Comments Comments (
    0
    ) |
What were the sources of funding? This study was supported by the Medical Research Service of the Department of Veterans Affairs and by grants HL 32050, HL 32050-S2, and HL 07640 from the National Heart, Lung, and Blood Institute, Bethesda, Maryland.
  • Comments Comments (
    0
    ) |




Results & Comparisons

No Results found.