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Study Title and Description

Transient exposure to coffee as a trigger of a first nonfatal myocardial infarction.



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 Transient exposure to coffee as a trigger of a first nonfatal myocardial infarction.
Author A Baylin,S Hernandez-Diaz,EK Kabagambe,X Siles,H Campos,
Country
Year 2006
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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)? Using a case-crossover design, we assessed the effect of coffee as a trigger of nonfatal acute myocardial infarction, and whether usual coffee intake and the underlying cardiovascular risk can modify this triggering effect of coffee.
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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 study population consists of incident cases of nonfatal myocardial infarction recruited between 1994 and 1998 in the Central Valley of Costa Rica. Eligible case subjects were men and women who were diagnosed as survivors of a first acute myocardial infarction by 2 independent cardiologists at any of the 3 recruiting hospitals in the Central Valley of Costa Rica. All cases met the World Health Organization criteria for myocardial infarction, which require typical symptoms plus either elevations in cardiac enzyme levels or diagnostic changes in the electrocardiogram. Enrollment was conducted while cases were in the hospital’s step-down-unit. Participation among eligible cases was 97%. Data Collection Sociodemographic characteristics, life style history, and medical history data were collected during an interview using a questionnaire with close-ended questions. We collected information on habitual intake of coffee using a food frequency questionnaire that has been developed and validated specifically to assess dietary intake among the Costa Rican population. The food frequency questionnaire presents 9 frequency options (never or < 1/month, 1–3/month, 1/week, 2–4/week, 5–6/week, 1/day, 2–3/day, 4–5/day, > 6/day) for most food items, including coffee. The portion size for coffee was fixed as one cup equivalent to 8 oz. Intake of coffee during the time previous to the myocardial infarction was collected using the following question: "When was the last time you had coffee before your heart attack?" Time was recorded in hours or days depending on the answer. The number of cups consumed was also recorded at the same time. Statistical Analysis We recruited 530 incident cases of nonfatal myocardial infarction for this analysis. Complete and consistent information was available for 503 cases regarding intake of coffee during the 24 hours and days before the myocardial infarction and regarding habitual intake of coffee. Using a case-crossover design, data were analyzed as a stratified analysis in which the stratifying variable is the individual patient. We selected a hazard period of 1 hour based on the absorption and bioavailability of caffeine in blood. Person-time exposed was calculated using the habitual frequency of coffee reported in the food frequency questionnaire. Person-time not exposed was calculated by subtracting the person-time exposed from the total hours in one year (8766 hours/year). The relative risk (RR) was estimated as the ratio between the observed exposure odds at the time of myocardial infarction onset and the expected exposure odds. Confidence intervals were calculated using methods for sparse follow-up data. Chi-square tests of homogeneity of RR across strata were used to assess effect modification by stratifying factors. We stratified by habitual intake of coffee and by risk factors for underlying cardiovascular risk. Habitual intake of coffee was stratified in 3 categories: light/occasional drinkers (</= 1 cup/day), moderate drinkers (2–3 cups/day), and heavy drinkers (>/= 4 cups/day). Underlying cardiovascular risk was estimated as the sum of the following risk factors: history of diabetes, history of hypertension, history of hypercholesterolemia, history of angina, smoking status, and waist circumference. Smoking status was defined as smoking 1 or more cigarettes/day. Waist circumference was measured twice, and the average of the 2 measurements was dichotomized according to the ATP III definition of metabolic syndrome (> 88 cm for women and > 102 cm for men). A cutoff of 3 risk factors was selected a priori based on the distribution of the sum of risk factors. The top quintile of the distribution corresponded to patients with 3 or more risk factors. Sedentary people were defined as those expending less than 10% of their daily energy in the performance of moderate-vigorous activities (at least 4 times the basal metabolism rate). All analyses were carried out with SAS (version 9.1; SAS Institute, Cary, NC) and PEPI (V.4.0 Salt Lake City, UT: Sagebrush Press; 2001).
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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) Non-fatal acute myocardial infarction (MI)
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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? Case-Control
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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 All cases met the World Health Organization criteria for myocardial infarction
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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.) Case crossover design; cases divided into 3 groups (low, middle, and high usual intake
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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) Many confounders were included in analysis, but only in terms of yes/no coffee drinkers, not stratified by amount
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What conflicts of interest were reported? No information provided
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Refid 16837823
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What were the sources of funding? Supported by grants HL071888 and HL60692 from the National Institutes of Health. Dr Baylin was supported by AHA fellowship 0425810T from the American Heart Association.
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Results & Comparisons

No Results found.