Comparison of associations of outcomes after stroke with estimated GFR using Chinese modifications of the MDRD study and CKD-EPI creatinine equations: results from the China National Stroke Registry

Abstract

Background: The CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) creatinine equation estimates glomerular filtration rate (GFR) more precisely than the MDRD (Modification of Diet in Renal Disease) Study equation. The risk implications of this equation have been compared with the MDRD Study equation in different demographic and clinical characteristics. However, whether a Chinese modification of this equation performs better than a Chinese modification of the MDRD Study equation in risk prediction in Chinese patients with stroke is unknown.

Study design: Prospective cohort study, China National Stroke Registry.

Setting & participants: 15,791 consecutive patients with stroke enrolled from September 2007 to August 2008; follow-up time, 1 year.

Predictor: Estimated GFR (eGFR) and eGFR categories computed using Chinese modifications of the MDRD Study and CKD-EPI creatinine equations.

Outcomes: All-cause mortality, recurrent stroke, stroke disability, combined end point of stroke or death.

Measurements: GFR was estimated by Chinese modifications of the MDRD Study (eGFRMDRD(CN)) and CKD-EPI (eGFRCKD-EPI(CN)) equations.

Results: The median value for eGFRCKD-EPI(CN) was higher than that for eGFRMDRD(CN) (87.3 vs 82.5 mL/min/1.73 m(2); P<0.001). 22.8% of patients were reclassified by the CKD-EPI China equation (11.5% [1,818/15,791] to a higher eGFR category, and 11.3% [1,789/15,791], to a lower eGFR category). Of patients with eGFRMDRD(CN) of 60-89 and 30-59 mL/min/1.73 m(2), 18.3% (1,299/7,090) and 18.4% (422/2,296) were reclassified upward to a higher eGFR category, respectively, reducing the CKD prevalence from 16.4% to 14.2%. Net reclassification improvement favored the Chinese modification of the CKD-EPI equation for the prediction of all-cause mortality, stroke recurrence, death, or stroke recurrence and stroke disability (net reclassification improvements of 0.05, 0.03, 0.04, and 0.1, respectively; all P<0.01).

Limitations: Relatively short follow-up time and no measurement of albuminuria.

Conclusions: Our findings suggest that a Chinese modification of the CKD-EPI equation may improve risk prediction of all-cause mortality, stroke recurrence, death or stroke recurrence and stroke disability more than a Chinese modification of the MDRD Study equation in Chinese stroke patients.

Keywords: Estimated glomerular filtration rate; epidemiology; outcome; stroke.