title: Vascular calcification in South African dialysis patients: ethnic variation, prevalence, detection and haemodynamic correlates.
abstract: OBJECTIVE
  Studies from the US have shown little effect of ethnicity on vascular calcification in dialysis patients. This has not been examined in the multi-ethnic population of South Africa where genetic and environmental differences may exist. We assessed the extent and severity of vascular calcification in South African dialysis patients according to race and known risk factors. We further evaluated the association of abdominal aorta calcification with coronary artery calcification.
  
  
  METHODS
  Seventy-five CKD-5D patients and 20 healthy controls were enrolled consecutively. All subjects underwent chest computed tomography for coronary calcium score and abdominal X-ray for abdominal aorta calcium score. Ambulatory blood pressure monitoring was generated via radial artery applanation tonometry.
  
  
  RESULTS
  Coronary calcification was present in 38.6% of patients and was associated with age and prior cardiovascular disease on multivariate analyses. The median coronary calcium score in black patients was 0 (IQR 0) and 66 in non-Blacks (IQR 383, P < 0.001); controls had a coronary calcium score of 0 (IQR 0). Black race remained a significant negative predictor for coronary calcification after adjustment, prevalence ratio = 0.14 and 95% confidence interval (CI): 0.0-0.53. Vascular calcification was not associated with any ambulatory blood pressure parameter. Using receiver operator characteristic curves, an abdominal aorta calcification score of ≥1 showed an area under the curve of 0.83 to predict a coronary calcium score ≥ 10.
  
  
  CONCLUSIONS
  Black race appears to protect from vascular calcification in South African CKD-5D patients and this warrants further study regarding the underlying mechanism. The abdominal X-ray is a useful screening tool for coronary calcification.
authors.affiliation: Renal Unit, Groote Schuur Hospital School of Public Health and Family Medicine, University of Cape Town 2-Military Hospital, Cape Town, South Africa. freercks@gmail.com
authors.forename: Robert
authors.initials: R
authors.lastname: Freercks
authors.forename: Charles
authors.initials: C
authors.lastname: Swanepoel
authors.forename: Henri
authors.initials: H
authors.lastname: Carrara
authors.forename: Sulaiman
authors.initials: S
authors.lastname: Moosa
authors.forename: Anthony
authors.initials: A
authors.lastname: Lachman
authors.forename: Brian
authors.initials: B
authors.lastname: Rayner
mesh_terms: D000328:Adult; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging; D001018:Aortic Diseases / Q000175:diagnosis / Q000208:ethnology* / Q000503:physiopathology / Q000517:prevention & control; D044383:Black People / Q000706:statistics & numerical data*; D001794:Blood Pressure; D018660:Blood Pressure Monitoring, Ambulatory / Q000379:methods; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000208:ethnology* / Q000503:physiopathology / Q000517:prevention & control; D003430:Cross-Sectional Studies; D005260:Female; D006439:Hemodynamics; D006801:Humans; D007674:Kidney Diseases / Q000208:ethnology / Q000503:physiopathology / Q000628:therapy*; D016014:Linear Models; D008297:Male; D008365:Manometry; D008875:Middle Aged; D015999:Multivariate Analysis; D010530:Peritoneal Dialysis / Q000009:adverse effects*; D011237:Predictive Value of Tests; D015995:Prevalence; D006435:Renal Dialysis / Q000009:adverse effects*; D018570:Risk Assessment; D012307:Risk Factors; D013019:South Africa / Q000453:epidemiology; D014057:Tomography, X-Ray Computed; D061205:Vascular Calcification / Q000175:diagnosis / Q000208:ethnology* / Q000503:physiopathology / Q000517:prevention & control