Prognostic usefulness of an age-adapted equation for renal function assessment in older patients with acute coronary syndrome

Background: Renal dysfunction negatively impacts survival in acute coronary syndrome patients. The Berlin Initiative Study creatinine-based (BIS crea ) equation has recently been proposed for renal function assessment in older persons. However, up to now it is unknown if the superiority of the new BIS crea equation, with respect to the most recommended chronic kidney disease epidemiology collaboration creatinine-based (CKD-EPI crea ) formula, would translate into better risk prediction of adverse events in older patients with acute coronary syndrome. Objectives: To study the impact of using estimated glomerular filtration rate calculated according to the BIS crea and CKD-EPI crea equations on mortality in acute coronary syndrome patients aged 70 years and over. Methods: Retrospectively, between 2011 and 2016, a total of 2008 patients with acute coronary syndrome (64% men; age 79±7 years) were studied. Follow-up was 18±10 months. Measures of performance were evaluated using continuous data and stratifying patients into three estimated glomerular filtration rate subgroups: ≥60, 59.9–30 and <30 mL/min/1.73 m 2 . Results: The two formulas afforded independent prognostic information over follow-up. However, risk prediction was most accurate using the BIS crea formula as evaluated by Cox proportional hazards models (hazard ratio (for each 10 mL/min/1.73 m 2 decrease) 1.47 vs. 1.27 with the CKD-EPI equation; P<0.001 for comparison), c-statistic values (0.69 vs. 0.65, respectively; P=0.04 for comparison) and Bayesian information criterion. Net reclassification improvement based on the estimated glomerular filtration rate categories significantly favoured BIS crea +9 (95% confidence interval 2–16%; P=0.02). Conclusions: Our findings suggest that the BIS crea formula may improve death risk prediction more than the CKD-EPI crea formula in older patients with acute coronary syndrome.