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Coffee drinking linked to hip fracture risk in postmenopausal Chinese women

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May 2, 2018

Drinking at least four cups of coffee per day may confer a greater risk for hip fracture in postmenopausal Chinese women, whereas moderate coffee consumption appears to reduce risk, according to results published in Bone.

Researchers found no associations between fracture risk and tea consumption.

Zhaoli Dai, PhD, a postdoctoral fellow at Boston University School of Medicine, and colleagues evaluated data from the Singapore Chinese Health Study, a population-based prospective cohort study of 63,154 adults aged 45 to 74 years at recruitment from April 1993 to December 1998.

At baseline, participants completed a 165-item, validated semiquantitative food frequency questionnaire, which documented dietary habits during the past year, including coffee and tea consumption. The Singapore Food Composition Database was used to estimate dietary intake of caffeine and other nutrients.

Questionnaires were linked to data from the hospital discharge database of the MediClaim System, which records inpatient discharge information from all hospitals in Singapore. Hip fracture cases were identified based on ICD codes and were confirmed through surgical notes or medical records.

Cox proportional hazard regression models were used to estimate HRs for risk for hip fracture by comparing the highest vs. the lowest category of coffee consumption. Two comparison groups were used for tea. Because there is approximately 100 mg of caffeine in one cup of coffee, the researchers assessed daily caffeine intake in the following categories: less than 100 mg (reference group); 100 mg to 199 mg; 200 mg to 299 mg; and at least 300 mg.

After a mean follow-up of 16.7 years, the nationwide hospital linkage revealed 2,502 incident hip fractures. The mean age at hip fracture was 79.4 years. According to the researchers, 72.7% of all hip fractures occurred in women, with age-standardized incidence rates of 294 per 100,000 person-years in women and 157 per 100,000 person-years in men. Daily coffee drinkers comprised approximately 70% of the cohort participants, and 47% drank at least one cup of tea per week. Men consumed more coffee or caffeine than women (P < .001).

In both sexes, those who sustained hip fractures were older and leaner than those without fractures (P < .058), the researchers wrote. Moreover, hip fractures were more likely to occur in smokers, those who consumed a less healthy diet, and those with a history of diabetes or stroke (P < .001).

Compared with participants who drank less than one cup of coffee per week, those who drank at least four cups per day had a significantly higher risk for hip fracture: Risk increased by 32% (HR = 1.32; 95% CI, 1.07-1.63) in the whole cohort, by 46% (HR = 1.46; 95% CI, 1.01-2.1) in men and by 33% (HR = 1.33; 95% CI, 1.02-1.72) in women, the researchers wrote. Among the cohort of mostly postmenopausal women, hip fracture risk was 12% lower among those who drank two to three cups per day (HR = 0.88; 95% CI, 0.76-1.01) vs. those who drank less than one cup per week.

“Our observations suggest that a high intake of coffee could increase hip fracture risk in both men and women, and that a moderate intake of coffee/caffeine could be associated with a lower risk in postmenopausal women,” the researchers wrote. “Future studies in other Asian populations ... are needed to verify these results and to determine the optimal amount of coffee/caffeine intake in relation to bone health in men and women.” – by Jennifer Byrne

Disclosures: The authors report no relevant financial disclosures.

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