Association of boiled and filtered coffee with incidence of first nonfatal myocardial infarction: the SHEEP and the VHEEP study.

OBJECTIVES: To evaluate the influence of consumption of filtered and boiled coffee, on the incidence of first nonfatal myocardial infarction.
DESIGN: Population-based case-control study. SETTING AND
SUBJECTS: The study base consisted of the population 45-65/70 years-old in two Swedish counties, Stockholm and Västernorrland, 1992/93-94. In all, 1943 cases of first nonfatal myocardial infarction were identified. For each case one control was selected from the study base concurrently with disease incidence by matching the sex, age and place of residence of the case. Information about coffee consumption and other factors was obtained by mailed questionnaire and a medical examination. The participation rate was 85% amongst cases and 74% amongst controls.
RESULTS: Men with a reported consumption of 7-9 dL filtered coffee per day showed an increased incidence of first myocardial infarction compared with consumers of 3 dL day-1 or less (RR: 1.32; 95% CI: 1.03-1.70). A consumption of at least 10 dL day-1 was associated with an RR of 1.93 (95% CI: 1.42-2.63) for filtered and 2.20 (95% CI: 1.17-4.15) for boiled coffee. Amongst women, no clear association was seen between consumption of filtered coffee and myocardial infarction but consumption of boiled coffee tended to be related to an increased incidence. Comparing subjects drinking boiled coffee with those drinking filtered coffee and adjusting for the amount consumed gave an increased incidence for boiled coffee amongst both men (RR: 1.41; 95% CI: 1.07-1.80) and women (RR: 1.63; 95% CI: 1.04-2.56).
CONCLUSIONS: Consumption of boiled coffee appears to increase the incidence of first nonfatal myocardial infarction. This increased incidence is consistent with randomized trials showing an adverse impact of boiled coffee on blood lipids.