Recent observational studies have suggested that calcium supplementation in healthy individuals is associated with adverse cardiovascular outcomes. Although people with chronic heart failure (CHF) were excluded from all osteoporosis studies such patients are often prescribed calcium. We aimed to investigate whether calcium supplements are associated with adverse outcomes in patients with CHF.Methods
Data were analysed from 1053 patients with CHF (LVEF ≤ 45%) who were enrolled in a prospective observational study for the occurrence of hospitalisation in the first year and long term mortality. Using pseudonymised electronic patient records held on the TPP SystmOne clinical database, outcomes were compared between patients who were and were not prescribed calcium supplementation. CHF patients with diabetes mellitus (DM) are at highest overall risk, so we prespecified a subgroup analysis of patients with DM.Results
During a mean follow-up of 3.2 years, there were 296 all-cause deaths and 181 cardiovascular deaths. Calcium supplement users (n = 170 (16.1%)) were older, and were more likely to be women, diabetic and more symptomatic based on NYHA class. They had lower haemoglobin, and worse renal function. They were less frequently prescribed ACE inhibitors, angiotensin receptor blockers and beta blockers. Calcium supplementation was associated with all-cause hospitalisation (odds ratio (OR) 1.60 (95% CI 1.12–2.30)), cardiovascular hospitalisation (OR 1.65 (95% CI 1.06–2.58)) and heart failure hospitalisation (OR 1.90 (95% CI 1.05–3.45)) but these associations were not statistically significant after adjustment for confounders.Results
In patients with DM (n = 275 (26.1%)), calcium users (n = 55 (20%)) were more likely to be female, had lower haemoglobin and albumin, had higher blood pressure and worse renal function compared to nonusers with DM. Although calcium supplementation in diabeticswas associated with an even greater increased risk of all-cause (OR 2.03 (95% CI 1.11–3.72)), cardiovascular (OR 2.33 (95% CI 1.17–4.63)), and heart failure (OR 2.50 (95% CI 1.04–6.00)) hospitalisation, after adjustment, this remained significant only for all-cause hospitalisation (OR 2.13 (95% CI 1.04–4.38))Conclusions
Patients with CHF are frequently prescribed calcium supplementation, despite no evidence from randomised, placebo controlled trials. Our data reveal a 50% higher hospitalisation risk, and in those at highest risk (those with DM), the risk of hospitalisation is more than doubled, and is statistically significant after correction for other factors. A larger cohort is needed to confirm the preliminary findings in this population.