Association of serum and urinary uromodulin and their correlates in older adults-The Cardiovascular Health Study.

Uromodulin is released into serum (sUMOD) and urine (uUMOD) exclusively by renal tubular cells. Both sUMOD and uUMOD are correlated with estimated glomerular filtration rate (eGFR), and associated with mortality and cardiovascular disease (CVD). However, no study to our knowledge has measured both sUMOD and uUMOD in the same population, thus the relationship of sUMOD with uUMOD with one another, and their respective correlates have not been evaluated simultaneously. We evaluated the correlations of sUMOD, uUMOD with eGFR in a random sub-cohort (n = 933) of the Cardiovascular Health Study and their associations with demographic and laboratory parameters and CVD risk factors using multi-variable linear regression analysis. The mean age of the cohort was 78 years, 40% were male and 15% were Black. The mean sUMOD level was 127 ng/mL, uUMOD was 30 500 ng/mL and eGFR was 63 mL/min/1.73 m2 . Correlation between sUMOD and uUMOD, adjusted for eGFR was moderate (r = 0.27 [95% confidence interval = 0.21-0.33]). The correlation of eGFR with sUMOD (r = 0.44 [0.39-0.49]) was stronger than with uUMOD (r = 0.21 [0.15-0.27]). In multi-variable analysis adjusting sUMOD for uUMOD and vice versa, sUMOD was independently associated with eGFR (ß = 1.3 [1.1-1.6]), log2 C-reactive protein (ß = -4.2 [-6.8 to -1.6]) and male sex (ß = -13.6 [-22.7 to -4.5]). In contrast, male sex was associated with higher uUMOD (ß = 3700 [400-7000]), while diabetes (ß = -6400 [-10 600 to -2100]) and hypertension (-4300 [-7500 to -1100]) were associated with lower uUMOD levels. We conclude that sUMOD is more strongly associated with eGFR compared with uUMOD. Correlates of sUMOD and uUMOD differ substantially, suggesting that apical and basolateral secretion may be differentially regulated.

Association of Serum Uromodulin With ESKD and Kidney Function Decline in the Elderly: The Cardiovascular Health Study.

RATIONALE & OBJECTIVE: Uromodulin is released by tubular epithelial cells into the serum and lower levels are associated with more severe interstitial fibrosis and tubular atrophy. Low serum uromodulin (sUMOD) levels are associated with mortality and cardiovascular disease. However, little is known about the association of sUMOD levels with long-term kidney outcomes in older adults, a population with a high prevalence of interstitial fibrosis and tubular atrophy. STUDY DESIGN: Case-cohort study and case-control study. SETTING & PARTICIPANTS: Random subcohort (n=933) and additional cases of end-stage kidney disease (ESKD) and kidney function decline (≥30% decline in estimated glomerular filtration rate [eGFR]) during follow-up of the Cardiovascular Health Study (CHS). PREDICTOR: sUMOD level. OUTCOMES: ESKD (n=14) from the random subcohort and all additional ESKD cases from outside the random subcohort (n=39) during follow-up (10 years, case-cohort study); kidney function decline of≥30% eGFR at 9 years of follow-up in individuals with repeated eGFR assessments from the random subcohort (n=56) and additional cases (n=123). 224 participants from the random subcohort served as controls (case-control study). ANALYTICAL APPROACH: Modified multivariable Cox regression for ESKD and multivariable logistic regression for kidney function decline. Both analyses adjusted for demographics, eGFR, urinary albumin-creatinine ratio, and other kidney disease progression risk factors. RESULTS: Mean age of the random subcohort was 78 years, 40% were men, 15% were black. Mean sUMOD level was 127±64ng/mL and eGFR was 63±19mL/min/1.73m2. In multivariable analysis, each 1-SD higher sUMOD level was associated with 63% lower risk for ESKD (HR, 0.37; 95% CI, 0.14-0.95). In demographic-adjusted analyses of kidney function decline, each 1-SD higher sUMOD level was associated with 25% lower odds of kidney function decline (OR, 0.75; 95% CI, 0.60-0.95); after multivariable adjustment, the association was attenuated and no longer significant (OR, 0.88; 95% CI, 0.68-1.14). LIMITATIONS: Possibility of survival bias in the kidney function decline analysis. CONCLUSIONS: Higher sUMOD levels may identify elderly persons at reduced risk for ESKD.

10-year follow-up of subclinical cardiovascular disease and risk of coronary heart disease in the Cardiovascular Health Study.

BACKGROUND: The incidence of coronary heart disease (CHD) is very high among individuals 65 years or older. METHODS: We evaluated the relationships between measurements of subclinical disease at baseline (1989-1990) and at the third-year follow-up examination (1992-1993) and subsequent incidence of cardiovascular disease and total mortality as of June 2001. Approximately 61% of the participants without clinical cardiovascular disease at baseline had subclinical disease based on our previously described criteria from the Cardiovascular Health Study. RESULTS: The incidence of CHD was substantially increased for participants with subclinical disease compared with those who had no subclinical disease: 30.5 per 1000 person-years with and 16.3 per 1000 person-years without for white individuals, and 31.2 per 1000 person-years with and 12.5 per 1000 person-years without for black individuals. The risk persisted over the entire follow-up period. Incidence rates were higher for men than for women with or without subclinical disease, but there was little difference in rates for black individuals and white individuals. CONCLUSIONS: In multivariable models, subclinical disease at baseline remained a significant predictor of CHD in both men and women; the hazard ratios (95% confidence intervals) of their relative risks were 1.64 (1.30-2.06) and 1.49 (1.21-1.84), respectively. The presence of subclinical disease substantially increased the risk of subsequent CHD for participants with hypertension, diabetes mellitus, or elevated C-reactive protein. In summary, subclinical disease is very prevalent among older individuals, is independently associated with risk of CHD even over a 10-year follow-up period, and substantially increases the risk of CHD among participants with hypertension or diabetes mellitus.