Abstract
BACKGROUND: The impact of early-stage chronic kidney disease (CKD) on cardiovascular outcomes, particularly when albuminuria is present, remains unclear. This study examined the associations between early CKD (stages 1 and 2) with and without albuminuria and the incidence of major adverse cardiovascular events (MACEs), heart failure (HF) and all-cause mortality. METHODS: A cohort of 456 015 participants from the UK Biobank was categorised by CKD stage using serum creatinine to calculate estimated glomerular filtration rate (eGFR) and urinary albumin-creatinine ratio (≥3 mg/mmol) to define albuminuria. Multivariable Cox proportional hazard models were applied to evaluate the associations between CKD stages and cardiovascular outcomes. Additionally, left ventricular mass (LVM), an intermediate cardiovascular risk marker, was assessed in a subset of participants using cardiovascular MRI. RESULTS: Compared with normal kidney function, the risk of adverse outcomes increased progressively with advancing CKD stages, except for stage 2 CKD without albuminuria. Stage 2 CKD with albuminuria was associated with higher risks of MACE (HR 1.32, 95% CI 1.25 to 1.38), HF (HR 1.79, 95% CI 1.67 to 1.92) and all-cause mortality (HR 1.51, 95% CI 1.44 to 1.58), comparable to stage 3A CKD without albuminuria. The presence of albuminuria significantly interacted with the relationships between CKD stages and outcomes. No significant differences in indexed LVM were observed between early-stage CKD with albuminuria and normal renal function. CONCLUSIONS: In early-stage CKD, albuminuria is independently associated with increased risks of MACE, HF and mortality. These findings support the use of albuminuria over eGFR decline alone for cardiovascular risk stratification in early CKD.