Letter to the Editor - Calcium Intake and Cardiovascular Disease Risk

In their review of calcium intake and cardiovascular disease, Chung and colleagues (1) did not perform a meta-analysis of randomized controlled trials (RCTs) as their title suggests. They identified only 2 trials reporting the effects of calcium plus vitamin D on cardiovascular events and 3 trials of calcium alone, whereas we have reported data on myocardial infarction or stroke from 13 studies of calcium with or without vitamin D (4 trials of calcium plus vitamin D and 11 trials of calcium monotherapy, with 2 studies comparing both calcium and calcium plus vitamin D with placebo) (2). For 6 trials, we used individual patient data. As in Chung and colleagues' review, cardiovascular event rates did not significantly increase in individual trials in our review but did when data were meta-analyzed (relative risk for myocardial infarction or stroke from calcium with or without vitamin D in 9 trials, 1.15 [95% CI, 1.03 to 1.27]) (2). Another meta-analysis of calcium monotherapy (5 trials involving 6333 participants) reported a relative risk for myocardial infarction of 1.37 (CI, 0.98 to 1.92) (3). Chung and colleagues do not comment on why their findings differ from those published previously.