title: Cystatin C- and creatinine-based equations in the assessment of renal function in HIV-positive patients prior to commencing Highly Active Antiretroviral Therapy.
abstract: BACKGROUND
  We evaluated the accuracy and precision of creatinine- and cystatin C-based prediction equations for estimating glomerular filtration rate compared to measured glomerular filtration rate in an antiretroviral-naive human immunodeficiency virus population.
  
  
  METHODS
  The study population consisted of 100 treatment-naive HIV patients. Glomerular filtration rate was estimated using the Cockcroft-Gault, Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations, as well as cystatin C-based equations (CKD-EPIcystatin C, cystatin Cvan Deventer and CKD-EPIcombined)) compared to (51)Cr-EDTA plasma clearance-measured glomerular filtration rate. We calculated percentage bias, standard deviation of the differences, accuracy within 15 and 30% of measured glomerular filtration rate and sensitivity and specificity for predicting measured glomerular filtration rate <60 mL/min/1.73 m(2).
  
  
  RESULTS
  Bias for all estimating glomerular filtration rate equations ranged from -9.4% to 38.4%. The CKD-EPIcombined without ethnicity correction factor equation had the least bias, 2.9% (-2.9 to 8.8). Bias was higher for the Modification of Diet in Renal Disease and CKD-EPI equation with the African-American ethnicity factor (38.4 and 33.7%) than without (14.2 and 15.3%). Standard deviation of the differences ranged from 29.2% (CKD-EPIcombined without ethnicity factor) to 54.0% (Modification of Diet in Renal Disease with ethnicity factor). Accuracy within 30% of measured glomerular filtration rate ranged from 78% for CKD-EPIcombined without ethnicity factor to 56.7% for the Cockcroft-Gault equation. Sensitivity for creatinine-based equations was less than 50% and for the CKD-EPIcystatin C equation was 75%.
  
  
  CONCLUSIONS
  Sensitivity of creatinine-based equations for predicting glomerular filtration rate was poor in this group of patients. The CKD-EPIcombined equation performed better than creatinine-based equations.
authors.affiliation: Department of Chemical Pathology, University of Witwatersrand and National Health Laboratory Services, Charlotte Maxeke Johannesburg Academic Hospital, Johannesburg, South Africa.
authors.forename: Tebogo
authors.initials: T
authors.lastname: Seape
authors.affiliation: Department of Chemical Pathology, University of Witwatersrand and National Health Laboratory Services, Charlotte Maxeke Johannesburg Academic Hospital, Johannesburg, South Africa Department of Chemical Pathology, University of Kwa Zulu Natal and National Health Laboratory Services, Inkosi Albert Luthuli Central Hospital, Durban, South Africa.
authors.forename: Verena
authors.initials: V
authors.lastname: Gounden
authors.affiliation: Department of Chemical Pathology, University of Witwatersrand and National Health Laboratory Services, Charlotte Maxeke Johannesburg Academic Hospital, Johannesburg, South Africa Lancet Laboratories, Auckland Park, Johannesburg, South Africa.
authors.forename: Hendrick E
authors.initials: HE
authors.lastname: van Deventer
authors.affiliation: Department of Surgery, University of Witwatersrand, Johannesburg, South Africa.
authors.forename: Geoffrey P
authors.initials: GP
authors.lastname: Candy
authors.affiliation: Department of Chemical Pathology, University of Witwatersrand and National Health Laboratory Services, Charlotte Maxeke Johannesburg Academic Hospital, Johannesburg, South Africa jaya.george@wits.ac.za.
authors.forename: Jaya A
authors.initials: JA
authors.lastname: George
mesh_terms: D000328:Adult; D023241:Antiretroviral Therapy, Highly Active; D003404:Creatinine / Q000097:blood*; D003430:Cross-Sectional Studies; D055316:Cystatin C / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D015658:HIV Infections / Q000097:blood* / Q000188:drug therapy / Q000503:physiopathology*; D006801:Humans; D007677:Kidney Function Tests / Q000379:methods* / Q000592:standards; D008297:Male; D012015:Reference Standards
chemical_list: D055316:Cystatin C; D003404:Creatinine
keywords: Estimated glomerular filtration rate; HIV; cystatin C; modification of diet in renal disease; prediction equations