The ratio of albumin to creatine in a person's urine is a powerful and independent predictor of prognosis of heart failure, concludes an Article in this week's issue of The Lancet. The Article is written by Professor John J V McMurray, British Heart Foundation Cardiovascular Research Centre, University of Glasgow, UK, and colleagues.
Increased excretion of albumin in urine is an established risk factor for mortality, cardiovascular events, and kidney disease in the general population, and in patients with diabetes, high blood pressure, and other types of cardiovascular disease. In this study, the authors aimed to assess the prognostic value of a spot urinary albumin to creatine ratio (UACR) in patients with heart failure, using date from the Candersartan in Heart failure: Assessment of Reduction in Mortality and morbidity (CHARM) Programme.
UACR was measuring at baseline and during follow up of 2310 patients. Patients were diagnosed as having very high albumin excretion (macroalbuminuria), less serious excretion (microalbuminuria) or normoalbuminuria. The researchers found 58% patients had normal UACR, 30% had microalbuminuria, and 11% had macroalbuminuria. The prevalence of increased UACR was similar in patients with reduced and preserved left ventricular ejection fractions (a measure of heart function). Patients with increased UACR were older, had more cardiovascular disease, worse kidney function, and a higher prevalence of diabetes than did those with normoalbuminuria.
However, a high prevalence of UACR was still noted in heart failure patients without diabetes, high blood pressure, or kidney disease. Higher UACR was associated with increased risk of death from cardiovascular causes or admission to hospital with worsening heart failure (the combined end point of the CHARM study), even after adjustment for kidney function, and diabetes/blood glucose status. Patients with microalbuminuria were 43% more likely to reach the combined end point than those with normal UACR; patients with macroalbuminuria were 75% more likely to reach the combined end point than those with normal UACR. When looking specifically at death due to cardiovascular causes, patients with microalbuminuria were 62% more likely to die from this cause than those with normal UACR, which rose to 76% more likely for patients with macroalbuminuria.
The authors conclude: "Increased UACR is a powerful and independent predictor of prognosis in heart failure…Because UACR is a simple, readily available clinical test that is widely used in primary and secondary care, it might be of value in risk stratification of patients with heart failure…Of Potential interest to physicians and patients is whether therapeutic reduction in albumin excretion, which did not occur with candesartan, might be useful in the prediction of improvement in clinical outcomes."
In an accompanying Comment, Dr Kevin Damman, Dr Hans L Hillege, and Dr Dirk J van Veldhuisen, Department of Cardiology, University Medical Center Groningen, Netherlands, say: "The role of albuminuria in heart failure deserves further attention and today's CHARM substudy offers a first glimpse into the relation between albuminuria and outcome, which seems in accordance with observations in the general population and other populations of patients…New prospective studies should answer the question of whether treatment of albuminuria can improve survival or at least, preserve kidney function in patients with heart failure."
Professor John J V McMurray, British Heart Foundation Cardiovascular Research Centre, University of Glasgow, UK. T) +44 (0) 141 330 3479 E) j.mcmurray@bio.gla.ac.uk
Dr Kevin Damman, Department of Cardiology, University Medical Center Groningen, Netherlands T) +31 503612345 E) k.damman@thorax.umcg.nl
For full Article and Comment, see: http://press.thelancet.com/albumin.pdf
Journal
The Lancet