Objective High serum calcium and phosphate levels have been linked to cardiovascular diseases and all-cause mortality but evidence from longitudinal studies is scarce, especially among patients with pre-existing coronary heart disease. The association between baseline calcium and phosphate and prognosis was examined in a cohort study of patients with stable coronary heart disease.
Methods Serum calcium and phosphate were measured in a cohort of initially 1206 patients undergoing a 3 week rehabilitation programme after an acute cardiovascular event and subsequently being followed-up for 8 years. Multivariate Cox regression was employed to assess the association of quartiles and continuous levels of calcium and phosphate with secondary cardiovascular events and all-cause mortality.
Results No significant risk elevations were observed for secondary cardiovascular event incidence in models adjusted for a variety of potential confounders. High calcium levels, however, were strongly associated with mortality risk in adjusted models (HRQ4vsQ1=2.39 (1.22 to 4.66)). In additional multivariable analyses, the calcium/albumin ratio was predictive for all-cause mortality (HRQ4vsQ1=2.66 (1.35 to 5.22)) and marginally predictive for cardiovascular event incidence (HRQ4vsQ1=1.74 (1.00 to 3.05)).
Conclusions Calcium and the ratio of calcium with albumin, its major binding protein, were strongly associated with all-cause mortality among patients with coronary heart disease. The underlying mechanisms and the clinical implications of these findings deserve further study.
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Funding This work was supported by grants from the German Ministry of Education and Research, Berlin, Germany (grant 01GD9820/0), the Association of German Pension Fund Agencies, Berlin, Germany (grant 02708) and the Willy–Robert–Pitzer Foundation, Bad Nauheim, Germany. The funders had no role in the study design, data collection, analysis and interpretation, writing of the manuscript or publication.
Competing interests None.
Ethics approval The study was approved by the ethics boards of the medical faculties of the universities of Ulm and Heidelberg and of the Physicians' Chambers of the German federal states of Baden-Württemberg and Hessen.
Provenance and peer review Not commissioned; externally peer reviewed.