Circulating osteocalcin (OC), a marker which is central in bone mineralization, may be involved in the atherosclerotic process and influence the risk of developing cardiovascular disease (CVD). We conducted a systematic review and meta-analysis of published observational evidence, to assess and quantify the associations of circulating OC (total, undercarboxylated, and carboxylated OC) with cardiovascular outcomes (clinical CVD endpoints and intermediate cardiovascular phenotypes).
Relevant studies were identified in a literature search of MEDLINE, EMBASE, and reference lists of relevant studies to March 2019. Mean differences and risk ratios with 95% CIs were aggregated using random-effects models.
Thirty-three observational studies (prospective and retrospective cohort, case-control, and cross-sectional) with data on 21,021 unique participants were eligible. The pooled risk ratio in a comparison of extreme fourths of total OC levels was 0.98 (95% CI 0.89, 1.08) for composite CVD. Circulating total OC levels were significantly lower in patients with cardiovascular conditions compared with those without these conditions -2.58 ng/ml (95% CI -3.85, -1.32; p < 0.001). Prospective and cross-sectional data showed significant inverse associations between total OC and traits such as aortic or coronarycalcification, coronary atherosclerosis or calcification, carotid intima-media thickness, and plaque score. There was limited data on carboxylated and undercarboxylated OC, with no evidence of associations.
Observational evidence generally supports inverse associations of circulating total OC with risk of atherosclerotic outcomes and CVD endpoints; however, the data were mostly based on cross-sectional evaluations. Large-scale prospective data are needed.