Prognostic impact of renal dysfunction on embolic stroke of undetermined source—Role beyond CHA2DS2‐VASc score: Results from Taiwan Stroke Registry

Abstract Background and purpose The CHA 2 DS 2 ‐VASc score has immense prognostic value in patients with embolic stroke of undetermined source (ESUS). We aimed to determine the usefulness of advanced renal dysfunction and its addition to the CHA 2 DS 2 ‐VASc score in improving predictive accuracy. Methods In total, 3775 ESUS patients were enrolled from a nationwide hospital‐based prospective study. Advanced renal dysfunction was defined as estimated glomerular filtration rate <30 ml/min per 1.73 m 2 or patients under dialysis. Clinical outcomes included recurrent stroke and 1‐year all‐cause mortality. Poor functional outcome was defined as a modified Rankin Scale >2 at first‐, third‐, and sixth‐month post‐stroke. The renal (R)‐CHA 2 DS 2 ‐VASc score was derived by including advanced renal dysfunction in the CHA 2 DS 2 ‐VASc score. Risk stratification improvement after including advanced renal dysfunction was assessed using C statistic, integrated discrimination improvement (IDI), and category‐free net reclassification index (NRI). Results After adjusting for confounding factors and CHA 2 DS 2 ‐VASc score, advanced renal dysfunction showed significant associations with all‐cause mortality (HR: 2.88, 95% CI: 1.92–4.34) and poor functional outcome at third‐ (OR: 2.69, 95% CI: 1.47–4.94) and sixth‐month post‐stroke (OR: 2.67, 95% CI: 1.47–4.83). IDI and NRI showed that incorporating advanced renal dysfunction significantly improved risk discrimination over the original CHA 2 DS 2 ‐VASc score. R‐CHA 2 DS 2 ‐VASc score ≥2 increased risk by 1.94‐fold (95% CI: 1.15–3.27) for all‐cause mortality, and ≥4 increased risk by 1.62‐fold (95% CI: 1.05–2.50) of poor functional outcome at third‐month post‐stroke and by 1.81‐fold (95% CI: 1.19–2.75) at sixth‐month post‐stroke. Conclusions Advanced renal dysfunction was significantly associated with clinical and functional outcomes in ESUS patients and may improve prognostic impact of the CHA 2 DS 2 ‐VASc score.