A meta-analysis of coffee, myocardial infarction, and coronary death

This paper presents a meta-analysis of 22 studies of coffee use and myocardial infarction or coronary death. In the eight case-control studies, a fairly homogeneous increased risk was found among coffee users (geometric mean rate ratio of 1.42 for 5 cups per day vs none, with 95% confidence limits of 1.30, 1.55, homogeneity P-value of 0.89). The 14 cohort studies tended to exhibit lower but very heterogeneous rate ratios, with a trend toward larger rate ratios in studies with longer follow-up periods and later publication dates (geometric mean rate ratio of 0.92 for the five cohort studies published up to 1981, 1.27 for the nine cohort studies published in 1986 or later; overall homogeneity P-value of 0.0008). The evidence thus remains ambiguous regarding both the existence and size of a coffee effect, and although a rate ratio of over 1.5 for 5 cups per day appears unlikely, stronger effects for 10-cup-per-day drinkers cannot be ruled out.