Cystatin C and albuminuria as risk factors for development of CKD stage 3: the Multi-Ethnic Study of Atherosclerosis (MESA).

BACKGROUND

The growing burden and morbidity of chronic kidney disease (CKD) warrant effective strategies for identifying those at increased risk. We examined the association of cystatin C level and albuminuria with the development of CKD stage 3.

STUDY DESIGN

Prospective observational study.

SETTING & PARTICIPANTS: 5,422 participants from the Multi-Ethnic Study of Atherosclerosis (MESA) with estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m(2).

PREDICTOR

Participants were categorized into 4 mutually exclusive groups: the presence or absence of microalbuminuria (albumin-creatinine ratio >17 and >25 μg/mg in men and women, respectively) in those with or without cystatin C level ≥1.0 mg/L.

OUTCOMES & MEASUREMENTS: Incident CKD stage 3 was defined as eGFR <60 mL/min/1.73 m(2) at the third or fourth visit and an annual decrease >1 mL/min/1.73 m(2). Poisson regression was used to evaluate incident rate ratios in unadjusted and adjusted analyses that include baseline eGFR.

RESULTS

Mean age was 61 years, 49% were men, 38% were white, 11% had diabetes, 13.7% had cystatin C level ≥1 mg/L, 8.4% had microalbuminuria, and 2.7% had cystatin C level ≥1 mg/L with microalbuminuria. 554 (10%) participants developed CKD stage 3 during a median follow-up of 4.7 years, and adjusted incidence rate ratios were 1.57 (95% CI, 1.19-2.07), 1.37 (95% CI, 1.13-1.66), and 2.12 (95% CI, 1.61-2.80) in those with microalbuminuria, cystatin C level ≥1 mg/L, and both, respectively, compared with those with neither.

LIMITATIONS

Relatively short follow-up and absence of measured GFR.

CONCLUSIONS

Cystatin C level and microalbuminuria are independent risk factors for incident CKD stage 3 and could be useful as screening tools to identify those at increased risk.