Nontraditional Risk Factors for Progression Through Chronic Kidney Disease Risk Categories: The Coronary Artery Risk Development in Young Adults Study.

BACKGROUND: There may be nontraditional pathways of chronic kidney disease (CKD) progression that are complementary to classical pathways. Therefore, we aimed to examine nontraditional risk factors for incident CKD and its progression. METHODS: We used the generally healthy population (n = 4382) starting at age 27-41 years in the Coronary Artery Risk Development in Young Adults (CARDIA) cohort, which is an observational longitudinal study. Nontraditional risk factors included forced vital capacity, inflammation, serum urate, and serum carotenoids. CKD risk category was classified using the estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (UACR) measured in 1995-1996 and repeated every 5 years for 20 years: No CKD, low risk, moderate risk, high risk, and very high risk. RESULTS: At baseline, 84.8% had no CKD (eGFR ≥60 mL/min/1.73 m2 and UACR <10 mg/g), 10.3% were in the low risk (eGFR ≥60 and UACR 10-29), and 4.9% had CKD (eGFR <60 and/or UACR ≥ 30). Nontraditional risk factors were significantly associated with the progression of CKD to higher categories. Hazard ratios per standard deviation of the predictor for incident CKD and its progression from the No CKD and low and moderate risk into CKD were inverse for forced vital capacity and serum carotenoids and positive for serum urate, GlycA, and C-reactive protein, the first 3 even after adjustment for conventional risk factors. CONCLUSION: Several nontraditional markers were significantly associated with an increased risk of progression to higher CKD categories in generally healthy young to middle-aged adults.

Serum phosphorus concentrations and arterial stiffness among individuals with normal kidney function to moderate kidney disease in MESA.

BACKGROUND AND OBJECTIVES: Higher phosphorus levels are associated with cardiovascular disease (CVD) events and mortality. Whether vascular stiffness may be responsible is unknown. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This study examined the cross-sectional associations of serum phosphorus with ankle brachial index (ABI), pulse pressure, and large and small artery elasticity by radial artery waveform analysis among 1370 individuals (440 with moderate chronic kidney disease) who did not have clinical CVD and participated in the Multi-Ethnic Study of Atherosclerosis. RESULTS: Fifty-nine (4%) individuals had high ABI (>1.30), a marker of peripheral arterial stiffness. Participants with phosphorus levels >4 mg/dl had greater than four-fold risk for high ABI compared with participants with phosphate levels <3 mg/dl (relative risk 4.6; 95% confidence interval 1.6 to 13.2; P = 0.01) after adjustment for demographics, traditional CVD risk factors, and kidney function. Higher phosphorus levels were also associated with greater pulse pressure and lesser large and small artery elasticity in unadjusted models, but these associations were attenuated after adjustment. CONCLUSIONS: Higher phosphorus levels are strongly associated with high ABI but not pulse pressure or large or small artery elasticity. If confirmed in future studies, then the association of higher phosphorus concentrations with CVD events may be partially mediated through peripheral arterial stiffness.