Determining the optimal cut-off value of the urinary albumin-to-creatinine ratio to detect atherosclerotic vascular diseases.

Background: We examined whether low-grade albuminuria, below the conventional cut-off value for microalbuminuria, was associated with atherosclerotic vascular diseases in 8897 community-dwelling Koreans aged ≥50 years.

Methods: The urinary albumin-to-creatinine ratio (UACR) was calculated using random spot urine. Common carotid artery (CCA) intimamedia thickness (IMT) and CCA internal diameter were measured using high-resolution B-mode ultrasonography, and carotid plaque was evaluated. Brachial-ankle pulse wave velocity (BaPWV) and the ankle-brachial index (ABI) were examined, and peripheral arterial disease was defined as ABI <0.9.

Results: Youden's indices, predicting abnormal atherosclerotic conditions, were greatest at a UACR cut-off value of ∼15 mg/g, below the threshold conventionally used to define microalbuminuria. Compared with low normoalbuminuria (UACR <15.0 mg/g), CCA IMT, CCA diameter, and BaPWV were significantly greater in individuals with high normoalbuminuria (UACR 15.0-29.9 mg/g), who also had a significantly higher risk of carotid plaque than did those with low normoalbuminuria.

Conclusions: Subclinical atherosclerotic vascular diseases developed at lower UACRs, below the conventional classification of microalbuminuria. Further longitudinal studies are needed to investigate the relationship between microalbuminuria and the development of subclinical atherosclerosis.