OBJECTIVES: The purpose of this retrospective, observational study was to evaluate the association between two key measures of kidney disease: estimated glomerular filtration rate (eGFR) and albuminuria, and serious adverse outcomes.

METHODS: Data were extracted from routine UK primary care and linked hospital data. Patients with a record of chronic kidney disease (CKD) were identified and their eGFR and albuminuria records classified, respectively, as G1 (normal/high) to G5 (end stage) and A1 (normal/mild) to A3 (severely increased) in accordance with international guidelines. Time-dependent Cox proportional hazard models were used to estimate risk and account for potentially confounding factors, incorporating eGFR and albuminuria staging, diabetes status, age, gender, prior comorbid events, smoking status, BMI, and prior antihypertensive therapy with ACE inhibitors or angiotensin receptor blockers (ARBs). eGFR category G2 (mildly decreased eGFR) and A1 were used as referents. Outcomes were kidney failure (dialysis or transplant), hospitalization for infection, and hospitalization for major adverse cardiovascular event (MACE; myocardial infarction or stroke).

RESULTS: We identified 106,419 patients with a record of CKD. For kidney failure, the adjusted hazard ratio (aHR) was 1.28, 1.06, 2.68, 15.01, and 114.14 for G1, G3a, G3b, G4, and G5, respectively, and 1.69, 2.52, and 3.56 for A2, A2/3, and A3, respectively. For MACE, the aHR was 1.40, 1.05, 1.28, 1.52, and 2.22, respectively, and 1.23, 1.06, and 1.60, respectively. For infections, the aHR was 0.88, 1.16, 1.40, 1.76, and 2.56, respectively, and, 1.16, 1.20, and 1.28, respectively. All aHRs were significant at the conventional level of significance.

CONCLUSIONS: eGFR was a distinct marker of adverse outcome in all three serious clinical endpoints, and albuminuria was an independent marker of adverse outcome.