Estimating glomerular filtration rate in acute coronary syndromes: Different equations, different mortality risk prediction.
OBJECTIVE
Renal dysfunction is a powerful predictor of adverse outcomes in patients hospitalized for acute coronary syndrome. Three new glomerular filtration rate (GFR) estimating equations recently emerged, based on serum creatinine (CKD-EPIcreat), serum cystatin C (CKD-EPIcyst) or a combination of both (CKD-EPIcreat/cyst), and they are currently recommended to confirm the presence of renal dysfunction. Our aim was to analyse the predictive value of these new estimated GFR (eGFR) equations regarding mid-term mortality in patients with acute coronary syndrome, and compare them with the traditional Modification of Diet in Renal Disease (MDRD-4) formula.


RESULTS
801 patients admitted for acute coronary syndrome (age 67.3±13.3 years, 68.5% male) and followed for 23.6±9.8 months were included. For each equation, patient risk stratification was performed based on eGFR values: high-risk group (eGFR<60ml/min per 1.73m(2)) and low-risk group (eGFR⩾60ml/min per 1.73m(2)). The predictive performances of these equations were compared using area under each receiver operating characteristic curves (AUCs). Overall risk stratification improvement was assessed by the net reclassification improvement index. The incidence of the primary endpoint was 18.1%. The CKD-EPIcyst equation had the highest overall discriminate performance regarding mid-term mortality (AUC 0.782±0.20) and outperformed all other equations (ρ<0.001 in all comparisons). When compared with the MDRD-4 formula, the CKD-EPIcyst equation accurately reclassified a significant percentage of patients into more appropriate risk categories (net reclassification improvement index of 11.9% (p=0.003)). The CKD-EPIcyst equation added prognostic power to the Global Registry of Acute Coronary Events (GRACE) score in the prediction of mid-term mortality.


CONCLUSIONS
The CKD-EPIcyst equation provides a novel and improved method for assessing the mid-term mortality risk in patients admitted for acute coronary syndrome, outperforming the most widely used formula (MDRD-4), and improving the predictive value of the GRACE score. These results reinforce the added value of cystatin C as a risk marker in these patients.
Cardiology Department, Coimbra University Hospital Centre, Portugal inesalm@gmail.com.
Inês
I
Almeida
Cardiology Department, Coimbra University Hospital Centre, Portugal.
Francisca
F
Caetano
Cardiology Department, Papworth Hospital, Cambridge, UK.
Sérgio
S
Barra
Cardiology Department, Coimbra University Hospital Centre, Portugal.
Marta
M
Madeira
Cardiology Department, William Harvey Hospital, Ashford, UK.
Paula
P
Mota
Maputo Heart Institute, Maputo, Mozambique.
António
A
Leitão-Marques
D054058:Acute Coronary Syndrome / Q000401:mortality*; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005919:Glomerular Filtration Rate; D006760:Hospitalization; D006801:Humans; D007674:Kidney Diseases / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D018570:Risk Assessment
Acute coronary syndrome; cystatin C; glomerular filtration rate; kidney function; prognosis; risk stratification