Introduction: Chronic kidney disease (CKD) is forecast to become the fifth leading cause of death globally by 2040. Retinal microvascular changes resulting from systemic vascular remodeling have been reported in association with CKD and may improve stratification of risk. We assessed associations between retinal microvascular parameters and urinary albumin-to-creatinine ratio (ACR) in a nested case-control cohort from the UK Biobank (UKBB) study.
Methods: A case-control study was undertaken in a subset of the UKBB population. Cases had an ACR ≥ 3mg/mmol, controls had an ACR < 3mg/mmol and were matched for age, gender and ethnicity. Macula centered fundus images were analyzed using the semi-automated software Vessel Assessment and Measurement Platform for Images of the REtina (VAMPIRE). Logistic regression models were constructed to assess associations between retinal microvascular parameters and ACR status. Fully adjusted models included age, gender, ethnicity, systolic blood pressure, diagnosis of diabetes, smoking status and fellow vessel caliber for models including arteriolar and venular caliber.
Results: In this interim analysis of 930 participants (453 cases, 477 controls), the mean age was 58 years (standard deviation [SD] 8) for cases and 59 (SD 8) for controls; 57% of cases and 53% of controls were female. Diabetes was present in 18% of cases and 9% of controls. In models adjusted for confounding variables, higher fractal dimension (FD) was significantly associated with reduced risk of albuminuria for both arterioles (odds ratio [OR] 0.06, 95% confidence interval [CI] 0.01, 0.38) and venules (OR 0.05, CI <0.01, 0.44). Retinal microvascular caliber and tortuosity were not significantly associated with albuminuria.
Conclusion: Higher FDs (denser retinal arteriolar and venular branching patterns) are associated with reduced cross-sectional risk of albuminuria in the subset of the UKBB population considered. Given the metabolic demands and hemodynamic principles governing vascular branching, altered retinal microvascular FDs may reflect metabolic disturbances and vascular calcification in CKD.