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

Abstract

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 m².

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 m² 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.