Background and purposeChronic kidney disease and atrial fibrillation (AF) are two commonly coexisting risk factors of stroke. The aim of this study was to compare the association between impaired renal function and poor prognosis in ischaemic stroke patients with versus without AF. MethodsPatients with ischaemic stroke in the China National Stroke Registry were included. Low estimated glomerular filtration rate (eGFR) on admission was defined as <60 ml/min/1.73 m(2). Outcomes included stroke recurrence, death, poor outcome defined as 3-6 on the modified Rankin Scale (mRS) and ordinal mRS at 12 months. ResultsOf 9154 patients included, 1143 (12.5%) patients had a low eGFR. Patients with a low eGFR had more presence of AF compared with those with an eGFR of 90 ml/min/1.73 m(2) [21.5% vs. 6.9%; odds ratio (OR) 1.77, 95% confidence interval (CI) 1.43-2.20]. An interaction of eGFR category by AF was observed for poor outcome and ordinal mRS (P for interaction = 0.04 and 0.002). In patients with AF, the OR with 95% CI of low eGFR was 1.86 (1.19-2.92) for stroke recurrence, 2.87 (1.82-4.52) for death, 1.83 (1.09-3.05) for poor outcome and 2.20 (1.52-3.18) for ordinal mRS. In patients without AF, low eGFR was only associated with death and ordinal mRS (OR 1.61, 95% CI 1.28-2.02; common OR 1.20, 95% CI 1.04-1.38; respectively). ConclusionsStroke patients with lower eGFR had more presence of AF. The associations of low eGFR with risk of poor prognosis in stroke patients with AF were stronger than those without AF. Click to view the accompanying paper in this volume.