title: Trends in the prevalence of reduced GFR in the United States: a comparison of creatinine- and cystatin C-based estimates.
abstract: BACKGROUND
  The US prevalence of reduced estimated glomerular filtration rate (eGFR) based on serum creatinine level increased during the decade ending in 2002. National Health and Nutrition Examination Survey (NHANES) cystatin C measurements recently were calibrated to the international standard, allowing for an independent test of the trend in prevalence of reduced eGFR using cystatin C level.
  
  
  METHODS
  Cross-sectional surveys performed during 2 periods.
  
  
  METHODS
  Nationally representative subsamples of adult participants from NHANES III (1988-1994) and the NHANES 1999-2002 surveys.
  
  
  METHODS
  Survey period.
  
  
  RESULTS
  Prevalence of reduced GFR, defined as eGFR <60 mL/min/1.73 m² based on levels of serum creatinine, cystatin C, or both (eGFRcr, eGFRcys, and eGFRcr-cys), using estimating equations developed by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI).
  
  
  METHODS
  Serum cystatin C level, measured from stored samples in 2006, calibrated to the international standard in 2012.
  
  
  RESULTS
  Between 1988-1994 and 1999-2002, the prevalence of reduced eGFRcr, eGFRcys, and eGFRcr-cys increased from 4.7% (95% CI, 4.1%-5.3%) to 6.5% (95% CI, 5.9%-7.1%) (P < 0.001), from 5.5% (95% CI, 4.6%-6.5%) to 8.7% (95% CI, 7.5%-10.0%) (P < 0.001), and from 4.4% (95% CI, 3.7%-5.2%) to 7.1% (95% CI, 6.2%-8.0%) (P < 0.001), respectively. The higher prevalence of reduced GFR in the later period was observed in all subgroups of age, race, sex, and GFR categories. After adjusting for changes in the US population by age, sex, race, diabetes, hypertension, and body mass index, prevalence ratios of reduced GFR in the later versus earlier survey were 1.24 (95% CI, 1.09-1.45), 1.34 (95% CI, 1.15-1.67), and 1.33 (95% CI, 1.17-1.65) using eGFRcr, eGFRcys, and eGFRcr-cys, respectively.
  
  
  CONCLUSIONS
  Likely underascertainment of persons with GFR <15 mL/min/1.73 m²; GFR was estimated and not measured; comparability of laboratory assays based on a calibration subsample.
  
  
  CONCLUSIONS
  The prevalence of reduced eGFRcys in the US civilian noninstitutionalized population increased between 1988-1994 and 1999-2002, confirming the increase observed in the prevalence of reduced eGFRcr.
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA. mgrams2@jhmi.edu
authors.forename: Morgan E
authors.initials: ME
authors.lastname: Grams
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Juraschek
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Selvin
authors.forename: Meredith C
authors.initials: MC
authors.lastname: Foster
authors.forename: Lesley A
authors.initials: LA
authors.lastname: Inker
authors.forename: John H
authors.initials: JH
authors.lastname: Eckfeldt
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Levey
authors.forename: Josef
authors.initials: J
authors.lastname: Coresh
mesh_terms: D000328:Adult; D003404:Creatinine / Q000097:blood*; D003430:Cross-Sectional Studies; D055316:Cystatin C / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D051436:Renal Insufficiency, Chronic / Q000097:blood* / Q000453:epidemiology* / Q000503:physiopathology; D014481:United States / Q000453:epidemiology
chemical_list: D055316:Cystatin C; D003404:Creatinine
keywords: Cystatin C; chronic kidney disease; estimating equations; prevalence