The impact of vascular calcification among dialysis-dependent South African patients: A 5-year follow-up study


Vascular calcification is a major risk factor for cardiovascular morbidity and mortality in patients with end-stage renal disease (ESRD). In Western countries, Blacks appear to have lesser degrees of vascular calcification compared to non-Blacks. However, there is no published data from sub-Saharan Africa.

This study assessed the 5-year change in vascular calcification and mortality in a previously published cohort of patients with ESRD. Vascular calcification was assessed by abdominal aortic calcification score and vascular stiffness by pulse wave velocity (PWV).

66 of the original 74 participants studied at baseline were identified. The median age was 46.6 years (37.6 - 59.2), and 57.6% were women. Abdominal aortic calcification showed no progression among Blacks (baseline range 0 - 5, follow-up range 0 - 8 (p = 1.00)), but a trend to progression among non-Blacks (baseline range 0 - 19, follow up range 0 - 22 (p = 0.066)). Black participants did not display a survival advantage (p = 0.870). Non-Blacks had higher parathyroidectomy rates than Blacks with 9/30 cases compared to 2/36 (p = 0.036). After adjustment for parathyroidectomy at follow-up, the odds ratio of having abdominal vascular calcification score of ≥ 1 amongst non-Blacks was 8.6-fold greater compared to Blacks (p = 0.03). A positive correlation (r = 0.5) was observed between PWV and abdominal aortic calcification (p = 0.047). Elevated baseline coronary artery calcification score and FGF-23 level at baseline were not associated with a difference in mortality.

There was no significant progression in vascular calcification among Blacks. After adjusting for increased parathyroidectomy rates, there was a greater progression of vascular calcification amongst non-Blacks compared to Blacks.