Examining the utility of cystatin C as a confirmatory test of chronic kidney disease across the age range in middle-aged and older community-dwelling adults

J Epidemiol Community Health. 2018 Apr;72(4):287-293. doi: 10.1136/jech-2017-209864. Epub 2018 Jan 13.


Background: Cystatin C has been proposed as a confirmatory test of chronic kidney disease (CKD). This is most applicable to older individuals with CKD, the majority of whom have a creatinine-based estimated glomerular filtration rate (eGFR) of 45-59 mL/min/1.73 m2 (CKD stage 3a). We sought to examine the utility of cystatin C as a confirmatory test of CKD across the age range in the general population of older adults.

Methods: Cross-sectional analysis of 5386 participants from The Irish Longitudinal Study on Ageing, a cluster-sampled national cohort of community-dwelling adults aged ≥50 years. Cystatin C and creatinine were measured simultaneously using standardised assays. Using generalised additive models, we modelled the distributions of creatinine and cystatin C per year of age from four distributional parameters: location, dispersion, skewness, kurtosis. Among participants with CKD stage 3a, we estimated the predicted probability of cystatin C eGFR <60 mL/min/1.73 m2 ('confirmed CKD') as a function of age.

Results: Median age was 62 years, 53% were female and median cystatin C eGFR was 80 mL/min/1.73 m2. We observed progressive variability in cystatin C with increasing age. Compared with creatinine, cystatin C levels rose sharply beyond the age of 65. Among participants with CKD stage 3a (n=463), the predicted probability of 'confirmed CKD' increased steadily with age, from 15% at age 50 to 80% at age 80.

Conclusions: The clinical utility of cystatin C may be maximised in middle-aged individuals, in whom the distribution of cystatin C is less variable than older adults, and the pretest probability of confirming CKD is lower.

Keywords: , Biostatistics; , Epidemiology of chronic diseases; , renaL; Ageing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Distribution
  • Aged
  • Aged, 80 and over
  • Aging*
  • Biomarkers / blood
  • Creatinine / blood*
  • Cross-Sectional Studies
  • Cystatin C / blood*
  • Female
  • Glomerular Filtration Rate / physiology*
  • Humans
  • Independent Living
  • Kidney / physiopathology*
  • Kidney Function Tests
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Renal Insufficiency, Chronic / blood
  • Renal Insufficiency, Chronic / diagnosis
  • Renal Insufficiency, Chronic / physiopathology*
  • Risk Factors


  • Biomarkers
  • Cystatin C
  • Creatinine