(C-231) Calcium Supplements and the Risk of CVD Recurrence: Real-World Evidence

Background: Calcium supplements are widely used, but their safety is questioned due to a potential link to cardiovascular risk. The impact of calcium supplements on individuals with major cardiovascular disease (CVD) remains unstudied.

Objectives: To investigate the association between calcium supplementation and the risk of CVD recurrence and all-cause mortality in patients with prior CVD.

Methods:

Design: A retrospective population-based study.
Setting: The territory-wide electronic health records in Hong Kong.
Participants: Individuals ≥ 40 years old and newly diagnosed with CVD from 1 January 2006 to 31 December 2015. Those who died on the same day as the event or during the hospitalization of the event were excluded.
Exposures: The treatment group consisted of CVD patients prescribed calcium supplements, while the control group consisted of those who never prescribed calcium supplements from 1 January 2005 to 31 December 2020.
Main Outcomes and Measures: CVD recurrence and all-cause mortality were the primary outcomes.
Statistical analysis: Propensity score (PS) matching was adopted to balance the baseline characteristics of treatment and control groups, and the Cox proportional hazard model was used to estimate relative hazards.

Results: The matched cohort included 17,720 CVD patients in each arm. Calcium supplementation is associated with an increased risk of recurrence of adverse CVD events (hazard ratio [HR], 1.10; 95% CI, 1.07-1.14) and a slightly reduced risk of all-cause mortality (HR, 0.97; 95% CI, 0.94-1.00). However, heterogeneity exists in the associations. The risk of cardiovascular disease recurrence and all-cause mortality is notably higher with calcium-only supplementation than calcium-with-vitamin D supplementation and in males than in females.

Conclusions: In patients with major CVD, calcium supplementation is linked to an increased risk of CVD recurrence. Caution should be exercised when prescribing or using calcium supplements among them, particularly in males. The combination of calcium and vitamin D supplementation may pose fewer concerns than calcium-only supplementation.