title: Value of Cystatin C-Based e-GFR Measurements to Predict Long-Term Tenofovir Nephrotoxicity in Patients With Hepatitis B.
abstract: BACKGROUND
  Cystatin C is a genuine marker for detecting minor reductions in estimated glomerular filtration rate (e-GFR).
  
  
  OBJECTIVE
  We aimed to investigate the efficiency of cystatin C levels in predicting nephrotoxicity due to antiviral therapy in patients with chronic hepatitis B virus infection.
  
  
  METHODS
  Seventy-six naive hepatitis B virus patients and 44 controls were enrolled in this prospective cohort study.
  
  
  METHODS
  Serum cystatin C, phosphate and creatinine levels, and urinary albumin/creatinine ratios of all patients were measured at baseline, 3rd, 12th, and 24th months. Nephrotoxicity was determined according to the amount of change in creatinine level at the fourth year of treatment compared with baseline ([INCREMENT]Cr0-4).
  
  
  RESULTS
  Mean age was 36.1 ± 9.2 years and 40 (52.2%) of patients were women. There was no significant difference between baseline values of tenofovir disoproxil fumarate and entecavir groups. Although the creatinine level at the fourth year of treatment was statistically nonsignificant compared with baseline in the entecavir group, it was significantly higher in the fourth year of tenofovir treatment compared with baseline (0.95 ± 0.27 mg/dL vs. 0.76 ± 0.16 mg/dL, P = 0.002). While the increase in [INCREMENT]Cr0-4 was ≥0.2 mg/dL in 43.2% of patients in the tenofovir group, this rate was 18.8% in the entecavir group. Diagnostic accuracy in identifying decreased renal function as area under the curve (AUC) was high for baseline serum cystatin C level; furthermore, the highest AUC was calculated for cystatin C plus creatinine-based e-GFR equation (AUC: 0.81, P < 0.001).
  
  
  CONCLUSIONS
  Long-term tenofovir disoproxil fumarate nephrotoxicity can be predicted by serum cystatin C plus creatinine-based e-GFR measured before treatment.
authors.affiliation: Department of Gastroenterology, Sisli Hamidiye Etfal Education and Research Hospital, Istanbul, Turkey.
authors.forename: Ali Riza
authors.initials: AR
authors.lastname: Koksal
authors.affiliation: Department of Gastroenterology, Sisli Hamidiye Etfal Education and Research Hospital, Istanbul, Turkey.
authors.forename: Huseyin
authors.initials: H
authors.lastname: Alkim
authors.affiliation: Department of Gastroenterology, Sisli Hamidiye Etfal Education and Research Hospital, Istanbul, Turkey.
authors.forename: Salih
authors.initials: S
authors.lastname: Boga
authors.affiliation: Department of Medical Education and Informatics, Meram Medical Faculty, Necmettin Erbakan University, Konya, Turkey.
authors.forename: Mehmet Sinan
authors.initials: MS
authors.lastname: Iyisoy
authors.affiliation: Department of Gastroenterology, Sisli Hamidiye Etfal Education and Research Hospital, Istanbul, Turkey.
authors.forename: Ilker
authors.initials: I
authors.lastname: Sen
authors.affiliation: Department of Biochemistry, Bakirkoy Dr. Sadi Konuk Education and Research Hospital, Istanbul, Turkey.
authors.forename: Sebnem
authors.initials: S
authors.lastname: Tekin Neijmann
authors.affiliation: Department of Gastroenterology, Sisli Hamidiye Etfal Education and Research Hospital, Istanbul, Turkey.
authors.forename: Canan
authors.initials: C
authors.lastname: Alkim
mesh_terms: D000328:Adult; D000998:Antiviral Agents / Q000009:adverse effects*; D015415:Biomarkers / Q000097:blood; D003404:Creatinine / Q000097:blood; D055316:Cystatin C / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D019694:Hepatitis B, Chronic / Q000097:blood / Q000188:drug therapy*; D006801:Humans; D007677:Kidney Function Tests / Q000379:methods*; D008297:Male; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D051437:Renal Insufficiency / Q000097:blood / Q000139:chemically induced / Q000175:diagnosis* / Q000517:prevention & control; D000068698:Tenofovir / Q000009:adverse effects*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000998:Antiviral Agents; D015415:Biomarkers; D055316:Cystatin C; D000068698:Tenofovir; D003404:Creatinine