Biomarkers of kidney function and prediction of death from cardiovascular and other causes in the elderly: A 9-year follow-up study.

BACKGROUND: Cystatin C is claimed to be superior to creatinine-based estimates of glomerular filtration rate (eGFRcr). The purpose of the study is to analyze whether cystatin C, creatinine, and/or estimated glomerular filtration rates (eGFR) predicted cardiovascular and/or non-cardiovascular deaths among Finnish elderly. METHODS: Hazard ratios (HR) of cystatin C, creatinine and eGFRs for cardiovascular and non-cardiovascular deaths. RESULTS: During a 9-year follow-up, 275 died, 192 deaths were a result of cardiovascular disease. In age-adjusted analyses, cystatin C predicted the risk of non-cardiovascular and cardiovascular death in men (HR for 0.1-unit increase 1.12 [95% CI, 1.04-1.19] for non-CVD deaths and 1.18 [1.09-1.28] for CVD deaths) and women (1.14 [1.07-1.21] and 1.14 [1.06-1.22], respectively). CKD-EPIcr-cyc predicted the risk of CVD deaths in men (HR for 5-unit decrease 1.17 [1.09-1.25]) and women (1.09 [1.02-1.17]) and non-CVD deaths in women (1.07 [1.01-1.14]). Also, MDRD (HR for 5-unit decrease 1.16 [1.05-1.27]) and CKD-EPI (HR for 5-unit decrease 1.15 [1.05-1.25]) predicted CVD deaths among men. After additional adjustments, predictive value of cystatin C remained significant. Also, the predictive value of CKD-EPIcr-cys remained significant in non-CVD deaths among women. CONCLUSION: Cystatin C was clearly the best predictor for cardiovascular and non-cardiovascular deaths among Finnish elderly. Serum cystatin C is more accurate for clinical decision making than creatinine-based eGFR equations or the combined CKD-EPIcr-cys equation in persons older than 64years.

Renal impairment associated with diabetes in the elderly.

OBJECTIVE: To characterize renal impairment associated with diabetes in older adults by serum markers of glomerular filtration rate and microalbuminuria tests. RESEARCH DESIGN AND METHODS: The study population consisted of 187 diabetic and 1,073 nondiabetic subjects (age range 64-100 years) participating in a cross-sectional, population-based survey in southwestern Finland. Renal function was estimated by serum cystatin C (Cys C), serum creatinine (Cr), and the urinary albumin-to-creatinine ratio, and determinants of elevated levels were assessed by multivariate analysis. RESULTS: Diabetes, compared to hypertension, was a more powerful determinant of elevated Cys C and Cr levels in the very old (age >or=80 years), whereas the impact of hypertension was more pronounced in the younger group (age <80 years). The prevalence of microalbuminuria among diabetic subjects was 29.7%, and 15% had elevated Cr levels, whereas the prevalence of elevated Cys C levels varied considerably depending on whether adult or age-adjusted reference limits were used (64.7 vs. 21.4%). In 64.1% of diabetic subjects with elevated Cys C levels based on age-adjusted reference limits and in 48.2% of subjects with elevated Cr levels, microalbuminuria was absent. CONCLUSIONS: The impact of diabetes on renal impairment changes with increasing age. Serum markers of glomerular filtration rate and microalbuminuria identify renal impairment in different segments of the diabetic population, indicating that serum markers as well as microalbuminuria tests should be used in screening for nephropathy in diabetic older people. The appropriate reference limit for Cys C in geriatric clinical practice must be defined by further research.

Serum cystatin C in the aged: relationships with health status.

BACKGROUND: Serum cystatin C (Cys C) is claimed to be superior to serum creatinine (Cr) in estimating glomerular filtration rate, but its utility in assessing renal function in the polymorbid elderly needs to be evaluated. METHODS: In a cross-sectional, community-based survey performed in Lieto in southwestern Finland, Cys C, Cr, and urinary albumin-creatinine ratio (ACR) were measured in 1,260 subjects aged 64 to 100 years. Associations of demographic characteristics and health status factors with levels of Cys C, Cr, and ACR were assessed by means of linear models. RESULTS: In men, hypertension, coronary heart disease, urinary infection, rheumatoid arthritis, glucocorticoid treatment, older age, and lower functional status were found to be significant predictors of higher Cys C values, whereas hypertension, coronary heart disease, urinary infection, older age, and increasing body mass index (BMI) significantly predicted higher Cr values. Among women, corresponding factors were hypertension, glucocorticoid treatment, age, functional status, and BMI for Cys C and hypertension, BMI, and age for Cr. Diabetes was significantly associated only with ACR. These factors explained 35% of variation in Cys C values in men and 34.5% in women versus only 14.8% and 11.3% for Cr, respectively. CONCLUSION: Glucocorticoid treatment was recognized as an independent Cys C-increasing factor, presumably nonglomerular. In comparison with Cys C, a considerably greater proportion of total variation in Cr values seems to be explained by extrarenal factors.