Adverse events from calcium supplementation: relationship to errors in myocardial infarction self-reporting in randomized controlled trials of calcium supplementation.

Author(s): Lewis JR, Zhu K, Prince RL

Affiliation(s): Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Nedlands, Western Australia, 6009; School of Medicine and Pharmacology, University of Western Australia, Crawley, Australia 6009. joshua.lewis@uwa.edu.au.

Publication date & source: 2011-12-02, J Bone Miner Res., [Epub ahead of print]

The clinical effects of calcium supplements on adverse events reporting have not been well described. This study reviews randomised controlled trial evidence of adverse events to clarify the epidemiology of these events. The hypothesis that patient self-report of myocardial infarction (MI) is increased in individuals receiving calcium supplementation is due to an increase in non-MI events incorrectly perceived by the patient as being due to MI, is examined. In seven RCTs summary self-reported gastrointestinal adverse event rates were more common in participants receiving calcium. These were described as constipation, excessive abdominal cramping, bloating, upper GI events, gastrointestinal disease, gastrointestinal symptoms and severe diarrhoea or abdominal pain (calcium 14.1%, placebo 10.0%), RR 1.43 95% CI 1.28 to 1.59, P < 0.001. Adjudicated functional gastrointestinal (GI) hospitalizations in one study were calcium 6.8%, placebo 3.6% (RR 1.92 95% CI 1.21 to 3.05, P = 0.006). Direct comparison of self-reported and adjudicated MI events in the two trials of dietary calcium supplementation showed self-reported MI rates of 3.6% in the calcium group and 2.1% in the placebo group. Following adjudication the MI rates were 2.4% in the calcium group and 1.6% in the placebo group (RR 1.45 95% CI 0.88 to 2.45, P = 0.145). These data support the hypothesis that calcium tablets increase the incidence of adverse GI events which may account for an increase in self-reported MI in calcium treated patients but not controls. (c) 2011 American Society for Bone and Mineral Research. Copyright (c) 2011 American Society for Bone and Mineral Research.