Serum Fetuin A in Hemodialysis: A Link Between Derangement of Calcium-Phosphorus Homeostasis and Progression of Atherosclerosis?

Background

Fetuin A, a circulating inhibitor of ectopic calcification, is downregulated in hemodialysis and has been shown to predict cardiovascular mortality in this setting. The association of altered calcium-phosphorus with serum fetuin A levels is still a matter of debate. Although carotid intima-media thickness (cIMT) is a strong predictor of major cardiovascular events, its association with serum fetuin A levels is poorly defined.

Study Design

Cohort study.

Participants & Settings

174 uremic patients on long-term hemodialysis therapy enrolled in 4 university hospitals.

Predictors

Serum fetuin A levels at the beginning of the study (T0) and after 12 months (T12).

Outcomes

Progression of atherosclerosis assessed by means of cIMT measurements at 24 months (T24); cardiovascular morbidity and mortality at 36 months.

Results

Serum fetuin A concentrations at T0 and T12 were 282.3 ± 79.4 and 290.0 ± 92.2 μg/mL, respectively. Mean T0 and T24 cIMT values were 1.02 ± 0.2 and 1.06 ± 0.2 mm, respectively (P < 0.001). Fatal and nonfatal cardiovascular disease occurred in 36 and 86 patients by 36 months, respectively. In multivariate logistic regression, higher calcium-phosphorus product was associated with lower serum fetuin A level (odds ratio, 0.96; 95% confidence interval [CI], 0.93 to 1.00; P = 0.02). Multiple regression analysis showed that T0 serum fetuin A level was associated with T24 cIMT (P = 0.01) after adjustments for age, cholesterol level, high-sensitivity C-reactive protein level, previous cardiovascular events, and T0 cIMT. In a multivariate Cox regression analysis, cardiovascular mortality was independently associated with a 1-tertile lower T0 serum fetuin A level, and a 1-tertile higher T0 cIMT value was independently associated with greater cardiovascular mortality (hazard ratio, 0.45; 95% CI, 0.15 to 0.65; P = 0.007 and hazard ratio, 10.00; 95% CI, 3.16 to 31.73; P < 0.001, respectively) after adjustment for age and previous cardiovascular events.

Limitation

Length of follow-up.

Conclusion

Calcium-phosphorus product in hemodialysis patients inversely correlated with serum fetuin A level, which, in turn, was associated inversely with progression of atherosclerotic lesions and cardiovascular mortality in this study population.

Index Words: Fetuin A, intima-media thickness, calcium-phosphorus, hemodialysis