Use of cystatin C levels in estimating renal function and prognosis in patients with chronic systolic heart failure

BACKGROUND: Estimates of glomerular filtration rate (GFR), including creatinine and creatinine based formulae, are inaccurate in extremes of GFR and substantially biased in patients with chronic heart failure (CHF).

OBJECTIVE: To investigate whether serum cystatin C levels would be a better, more accurate and simple alternative for estimation of GFR and prognosis in CHF.

DESIGN: Cohort study.

SETTING: Chronic heart failure. PATIENTS, INTERVENTIONS AND MAIN OUTCOME MEASURE: In 102 CHF patients, the correlation between GFR as estimated by (125)I-iothalamate clearance (GFR(IOTH)), the modification of diet in renal disease formula (GFR(MDRD)) and cystatin C was investigated. The combined endpoint consisted of the first occurrence of all cause mortality, heart transplantation or admission for CHF within 24 months.

RESULTS: Mean age was 58±12 years; 77% were male. Mean left ventricular ejection fraction was 28±9%. Mean GFR(IOTH) was 75±27 ml/min/1.73 m(2), while median cystatin C levels were 0.80 (0.69-1.02) mg/l. GFR(IOTH) was strongly correlated with all renal function estimates, including 1/cystatin C (r=0.867, p<0.001). GFR(IOTH) was better predicted by 1/cystatin C compared to 1/serum creatinine (z=3.12, p=0.002), but equally predicted compared to GFR(MDRD) (z=0.92, p=0.356). Serum 1/cystatin C was a strong independent predictor of prognosis (HR: 2.27 per SD increase, 95% CI 1.12 to 4.63), comparable to GFR(MDRD).

CONCLUSIONS: Cystatin C is an accurate and easy estimate of renal function with prognostic properties superior to serum creatinine and similar to creatinine based formulae in patients with CHF.