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Study Title and Description

Coffee, tea and caffeine consumption in relation to osteoporotic fracture risk in a cohort of Swedish 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 bone and calcium balance outcomes?
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Primary Publication Information
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TitleData
Title Coffee, tea and caffeine consumption in relation to osteoporotic fracture risk in a cohort of Swedish women.
Author H Hallström,A Wolk,A Glynn,K Michaëlsson,
Country
Year 2006
Numbers

Secondary Publication Information
There are currently no secondary publications defined for this study.


Extraction Form: Bone & Calcium Outcomes
Design Details
Question... Follow Up Answer Follow-up Answer
Refid 16758142
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What outcome is being evaluated in this paper? Bone and Calcium
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What is the objective of the study (as reported by the authors)? The principal aim of this study was to investigate the association between consumption of coffee, caffeinated tea and caffeine intake and the risk of incident osteoporotic fractures in a large prospective population-based cohort of Swedish women, 40–76 years old at the start of the study. A secondary aim was to evaluate whether the level of dietary calcium influenced these fracture risk estimates
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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) Participants: Women born between 1914 and 1948 and resident in Uppsala county invited via mail to participate in a mammography screening between 1988 and 1990; mailing included a questionnaire re: demographic and lifestyle factors. After exclusions, 31,527 were included in the study. Dietary assessment: Food frequency questionnaire (FFQ) used to determine consumption of caffeine sources including: coffee, tea, caffeinated soft drinks and chocolate. No information about supplements or medicines containing caffeine was obtained. Eight predefined frequency categories were used that ranged from "never/seldom" to "four times or more per day." Caffeine intake was computed by multiplying the frequency of consumption of each unit of food by the nutrient content of specified portions derived from a database created by the Swedish National Administration. Consumption of one cup (150 ml) of coffee corresponded to an intake of 80 mg of caffeine. Validity of nutrient estimates evaluated in a subsample. Fracture cases: All types of fracture considered typical osteoporotic fractures were identified. Fracture cases in the study cohort were identified by matching the unique personal identification number of the study participants with the local outpatient registers, hospital discharge records and X-ray records from January 1988 through December 2000. Ascertainment of hip fracture cases was completed by use of the nationwide Swedish inpatient register. Statistics: Cox proportional hazards models were used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) measuring the association between exposure and the occurrence of osteoporotic fractures. The women were grouped into four categories of consumption: <1 cup/day, 1 cup/day, 2–3 cups/day and 4 cups (600 ml) or more per day for coffee and for tea consumption, and quintiles of caffeine intake. The basic model used to estimate HRs included age at study entry divided into 5-year age groups. In a multivariate model we further included height, weight, intake of vitamin D, vitamin A, calcium, phosphorus, alcohol and energy (all continuous), educational level (low vs high) and marital status (married or cohabitant vs single or widowed). To obtain a more limitless view of the shape of the association between consumption of caffeine and the risk of osteoporotic fractures a restricted Cox’s regression spline line model was also applied.
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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) Risk of fracture (multiple sites evaluated - proximal femur, i.e. hip fractures, fractures of the pelvis, spine, distal forearm and proximal humerus.)
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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 Fracture cases in the study cohort were identified by matching the unique personal identification number of the study participants with the local outpatient registers, hospital discharge records and X-ray records from January 1988 through December 2000. In addition, the ascertainment of hip fracture cases was completed by use of the nationwide Swedish inpatient register.
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Caffeine (general) Caffeine (general)
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Coffee, Chocolate, energy drink, gum, medicine/supplement, soda, tea, other? coffee, 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.) Multiple comparisons based on four categories of consumption: <1 cup/day, 1 cup/day, 2–3 cups/day and 4 cups (600 ml) or more per day for coffee and for tea consumption, and quintiles of caffeine 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) The basic model used to estimate HRs included age at study entry divided into 5-year age groups. In a multivariate model we further included height, weight, intake of vitamin D, vitamin A, calcium, phosphorus, alcohol and energy (all continuous), educational level (low vs high) and marital status (married or cohabitant vs single or widowed).
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What were the sources of funding? This study was supported by grants from the Swedish Research Council.
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What conflicts of interest were reported? Not addressed by authors
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Results & Comparisons

No Results found.