For the 338 044 participants in UKB with available data on serum cystatin C and urinary albumin-to-creatinine ratio, there were broadly similar associations of CHD or stroke with cystatin C–based eGFR as creatinine-based eGFR equations, but only when eGFR values were lower than ≈90 mL·min–1·1.73 m–2. This evidence concerns the gene CST3 and Stroke.