Background: To analyse prospectively the effect of calcium or calcium+D supplementation on coronary heart disease (CHD) in 52-62-year-old women.
Methods and results: 10,555 52-62-year-old women from the population-based Kuopio Osteoporosis Risk Factor and Prevention Study (OSTPRE) who did not have CHD at baseline were followed for nearly 7 years in 1994-2001. Information about use of calcium supplements and health events was obtained from two repeated questionnaires in 1989 and 1994. Information about causes of death during the follow-up was obtained from the Statistics Finland. Information about CHD and other disease morbidity before and during the follow-up was obtained from the Registry of Specially Refunded Drugs of the Finnish Social Insurance Institution (SII). Cox's proportional-hazards models were used to estimate the risk of CHD morbidity related to the use of calcium supplements. At baseline, 2723 women reported current use of calcium or calcium+D supplementation. During the follow-up, CHD was diagnosed in 513 women. Compared to non-users of calcium/calcium+D supplements, the multivariate adjusted hazard ratio (HR) of CHD was 1.24 (95% CI 1.02-1.52) in women who used these supplements. The multivariate adjusted HR for CHD morbidity in postmenopausal women who used calcium/calcium+D supplements was 1.26 (95% CI 1.01-1.57).
Conclusions: Calcium or calcium+D supplementation appears to increase the risk of CHD among women before old age.