Cystatin C could improve chronic kidney disease (CKD) classification in HIV-infected women relative to serum creatinine.
Retrospective cohort analysis.
Cystatin C and creatinine were measured from specimens taken and stored during the 1999–2000 exam among 908 HIV-infected participants in the Women’s Interagency HIV study (WIHS). Mean follow-up was 10.2 years. The associations of baseline categories (<60, 60–90, and >90 mL/min/1.73m2) of creatinine eGFR (eGFRcr), cystatin C eGFR (eGFRcys), and combined creatinine-cystatin C eGFR (eGFRcr-cys) with all-cause mortality were evaluated using multivariable Cox regression. The net reclassification index (NRI) was calculated to evaluate the effect of cystatin C on reclassification of CKD staging.
The prevalence of CKD (eGFR<60) at baseline was higher with eGFRcys (10.1%) compared to eGFRcr (6.7%, p=0.0006) and eGFRcr-cys (7.5%, p=0.011). Relative to eGFR >90, the eGFR <60 category by eGFRcys (Adjusted HR: 2.56; 95% CI: 1.63, 4.02), eGFRcr-cys (3.11; 1.94–5.00), and eGFRcr (2.34; 1.44–3.79) was associated with increased mortality risk. However, the eGFR 60–90 category was associated with increased mortality risk for eGFRcys (1.80; 1.28–2.53) and eGFRcr-cys (1.91; 1.38–2.66) but not eGFRcr (1.20; 0.85–1.67). The overall NRI for mortality was 26% when reclassifying from eGFRcr to eGFRcys (p<0.001) and was 20% when reclassifying from eGFRcr to eGFRcr-cys (p<0.001).
Cystatin C detected a higher prevalence of CKD relative to creatinine and improves CKD staging relative to creatinine by reclassifying individuals at the highest mortality risk to lower eGFR categories.
Creatinine; Cystatin C; Glomerular Filtration Rate; HIV; Mortality; Kidney; Women
Atrial fibrillation (AF) is common in end-stage renal disease (ESRD), but the relationship between more modest decrements in kidney function or albuminuria with AF is uncertain. Among 956 outpatients with coronary heart disease (CHD), we assessed kidney function by 3 methods (cystatin C-based [eGFRcys] and creatinine-based [eGFRCr] estimated glomerular filtration rate, and urinary albumin-to-creatinine ratio [ACR]) and prevalent AF by surface electrocardiogram. Multivariable logistic regression evaluated the associations of each measure of kidney function with AF. The mean eGFRcys was 71 ± 23 ml/min/1.73m2 and median ACR was 10 mg/g (interquartile range 6 – 19 mg/g). Forty subjects (4%) had prevalent AF. Compared to participants with eGFRcys in the highest tertile (eGFRcys > 79), those with eGFRcys in the lowest tertile (eGFRcys < 62) had more than 3-fold greater odds of AF (OR 3.43; 95% CI 1.18 – 9.97) after multivariate adjustment for traditional CVD risk factors. This association remained significant with further adjustment for ACR (OR 3.37; 95% 1.02 – 11.14). Results were similar for eGFRCr, but did not reach statistical significance (OR 1.59; 95% CI 0.57 – 4.40). Participants with ACR in the highest tertile (ACR > 15 mg/g) had more than 4-fold greater odds of AF compared to participants in the lowest ACR tertile (ACR < 7 mg/g); an association that remained significant after adjustment for eGFRcys (OR 4.36; 95% CI 1.45 – 13.05) or eGFRCr (OR 4.61; 95% CI 1.56 – 13.66). In conclusion, among outpatients with CHD, lower eGFRcys and higher ACR are each associated with prevalent AF, independent of one another.
Previous research has demonstrated an increase in carotid intima–media thickness (cIMT) in HIV-infected individuals compared to controls. However, the reason for this increased level of subclinical vascular disease is unknown.
To identify HIV-related risk factors for increased cIMT.
We evaluated the relationship between HIV-related characteristics (including markers of HIV disease severity and use of antiretroviral therapy) and cIMT measurements in the internal/bulb and common carotid regions among 538 HIV-infected participants from the Study of Fat Redistribution and Metabolic Change in HIV Infection (FRAM). We used Bayesian model averaging to estimate the posterior probability of candidate HIV and non-HIV-related risk factors being true predictors of increased cIMT. Variables with a posterior probability of more than 50% were used to develop a selected regression model for each of the anatomic regions.
For common cIMT, the Bayesian model selection process identified age, African-American race, and systolic and diastolic blood pressure with probability more than 95%, HDL cholesterol with probability 85% and Hispanic ethnicity with probability 51%. Among the HIV-related factors included in the analysis, only tenofovir use was selected (51% probability). In the selected model, duration of tenofovir use was associated with lower common cIMT (−0.0094 mm/year of use; 95% confidence interval: −0.0177 to −0.0010). For internal cIMT, no HIV-related risk factors were above the 50% posterior probability threshold.
We observed an inverse association between duration of tenofovir use and common carotid cIMT. Whether this association is causal or due to confounding by indication needs further investigation.
atherosclerosis; carotid intima–media thickness; HIV; tenofovir
Serum creatinine and cystatin C are used as markers of glomerular filtration rate (GFR). The performance of these GFR markers relative to exogenously measured GFR (mGFR) in HIV-positive individuals is not well established.
We assessed the performance of the chronic kidney disease epidemiology collaboration equations based on serum concentrations of creatinine (eGFRcr), cystatin C (eGFRcys) and both biomarkers combined (eGFRcr-cys) in 187 HIV-positive and 98 HIV-negative participants. Measured GFR was calculated by plasma iohexol clearance. Bias and accuracy were defined as the difference between eGFR and mGFR and the percentage of eGFR observations within 30% of mGFR, respectively. Activated CD4 and CD8 T-cells (CD38+ HLA-DR+) were measured by flow cytometry.
The median mGFR was >100 ml/min/1.73 m2 in both groups. All equations tended to be less accurate in HIV-positive than in HIV-negative subjects, with eGFRcr-cys being the most accurate overall. In the HIV-positive group, eGFRcys was significantly less accurate and more biased than eGFRcr and eGFRcr_cys. Additionally eGFRcys bias and accuracy were strongly associated with use of antiretroviral therapy, HIV RNA suppression, and percentages of activated CD4 or CD8 T-cells. Hepatitis C seropositivity was associated with larger eGFRcys bias in both HIV-positive and HIV-negative groups. In contrast, eGFRcr accuracy and bias were not associated with HIV-related factors, T-cell activation, or hepatitis C.
The performance of eGFRcys relative to mGFR was strongly correlated with HIV treatment factors and markers of T-cell activation, which may limit its usefulness as a GFR marker in this population.
Systematic differences between readers or equipment in imaging studies are not uncommon; failure to account for such differences when using Carotid Ultrasonography may introduce bias into associations between carotid intima media thickness (cIMT) and outcomes. We demonstrate the impact of this source of systematic measurement error (SME) using data on 5,521 participants from the Multi-Ethnic Study of Atherosclerosis (MESA) and 661 participants from the Study of Fat Redistribution and Metabolic Change in HIV Infection (FRAM). Participants were between 37 and 78 years old. Two outcomes were considered: (1) the effect of HIV infection on cIMT (between study) and (2) the association of cIMT with cardiovascular events (within study). All estimates were adjusted for demographics (age, gender, and ethnicity) and for traditional cardiovascular disease risk factors (smoking, blood pressure, diabetes and cholesterol). When comparing the FRAM and MESA cohorts to estimate the association of HIV infection on common cIMT, accounting for machine and reader variability (between study variability) reduced the difference associated with HIV infection from +0.080 mm (95% Confidence Interval (CI):0.065–0.095) to +0.037 mm (95% CI:0.003 to 0.072) while internal cIMT declined from +0.254 mm (95% CI:0.205–0.303) to +0.192 mm (95% CI:0.076–0.308). Attenuation of the association between cIMT and cardiovascular endpoints occurred when within study reader variability was not accounted for. The effect of SME due to use of multiple readers or machines is most important when comparisons are made between two different study populations. Within-cohort measurement error dilutes the association with events.
Carotid intima media thickness; Measurement error; Bias; Carotid ultrasonography
The US prevalence of reduced estimated glomerular filtration rate (eGFR) based on serum creatinine increased over the decade ending in 2002. National Health and Nutrition Examination Survey (NHANES) cystatin C measurements were recently calibrated to the international standard, allowing for an independent test of the trend in prevalence of reduced eGFR using cystatin C.
Cross-sectional surveys performed during two periods.
Setting & Participants
Nationally representative subsamples of adult participants from NHANES III (1988–1994) and the NHANES 1999–2002 surveys.
Prevalence of reduced GFR, defined as eGFR<60ml/min/1.73m2 based on serum creatinine, cystatin C, or both (eGFRcr, eGFRcys, eGFRcr-cys), using estimating equations developed by the Chronic Kidney Disease Epidemiology Collaboration (CKDEPI).
Serum cystatin C, measured from stored samples in 2006, calibrated to the international standard in 2012.
Between 1988–1994 and 1999–2002, the prevalence of reduced eGFRcr, eGFRcys and eGFRcr-cys increased from 4.7% (95% CI, 4.1%–5.3%) to 6.5% (95% CI, 5.9%–7.1%; p<0.001), from 5.5% (95% CI, 4.6%–6.5%) to 8.7% (95% CI, 7.5%–10.0%; p<0.001), and from 4.4% (95% CI, 3.7%–5.2%) to 7.1% (95% CI, 6.2%–8.0%; p<0.001), respectively. The higher prevalence of reduced GFR in the later period was observed in all subgroups of age, race, sex, and GFR categories. After adjusting for changes in the US population by age, sex, race, diabetes, hypertension, and body mass index, the prevalence ratio of reduced GFR in the later versus earlier survey was 1.24 (95% CI, 1.09–1.45), 1.34 (95% CI, 1.15–1.67), and 1.33 (95% CI, 1.17–1.65) using eGFRcr, eGFRcys, and eGFRcr-cys, respectively.
Likely under-ascertainment of persons with GFR<15 ml/min/1.73m2; GFR was estimated and not measured; comparability of laboratory assays based on a calibration subsample.
The prevalence of reduced eGFRcys in the US civilian, non-institutionalized population increased between 1988–1994 and 1999–2002, confirming the increase observed in the prevalence of reduced eGFRcr.
cystatin C; chronic kidney disease; estimating equations; prevalence
Few studies have examined the impact of childhood obesity on later kidney disease, and consequently, our understanding is very limited.
Longitudinal population-based cohort.
Setting & Participants
The Medical Research Council National Survey of Health and Development, a socially stratified sample of 5,362 singletons born in 1 week in March 1946 in England, Scotland, and Wales, of which 4,340 were analyzed.
Early-life overweight latent classes (never, prepubertal only, pubertal onset, or always), derived from repeated measurements of body mass index between ages 2 and 20 years.
Outcomes & Measurements
The primary outcome was chronic kidney disease (CKD), defined as creatinine- or cystatin C–based estimated glomerular filtration rate (eGFRcr and eGFRcys, respectively) <60 mL/min/1.73 m2 or urine albumin-creatinine ratio (UACR) ≥3.5 mg/mmol measured at age 60-64 years. Associations were explored through regression analysis, with adjustment for socioeconomic position, smoking, physical activity level, diabetes, hypertension, and overweight at ages 36 and 53 years.
2.3% of study participants had eGFRcr <60 mL/min/1.73 m2, 1.7% had eGFRcys <60 mL/min/1.73 m2, and 2.9% had UACR ≥3.5 mg/mmol. Relative to being in the never-overweight latent class, being in the pubertal-onset– or always-overweight latent classes was associated with eGFRcys-defined CKD (OR, 2.04; 95% CI, 1.09-3.82). Associations with CKD defined by eGFRcr (OR, 1.27; 95% CI, 0.71-2.29) and UACR (OR, 1.33; 95% CI, 0.70-2.54) were less marked, but in the same direction. Adjustment for lifestyle and health factors had little impact on effect estimates.
A low prevalence of CKD resulted in low statistical power. No documentation of chronicity for outcomes. All-white study population restricts generalizability.
Being overweight in early life was found to be associated with eGFRcys-defined CKD in later life. The associations with CKD defined by eGFRcr and UACR were less marked, but in the same direction. Reducing or preventing overweight in the early years of life may significantly reduce the burden of CKD in the population.
Childhood obesity; chronic kidney disease; estimated glomerular filtration rate
Carriers of the T allele of the single-nucleotide polymorphism rs13038305 tend to have lower cystatin C levels and higher cystatin C-based estimated glomerular filtration rate (eGFRcys). Adjusting for this genetic effect on cystatin C concentrations may improve GFR estimation, reclassify cases of CKD, and strengthen risk estimates for cardiovascular disease (CVD) and mortality.
Setting & Population
Four population-based cohorts: Atherosclerosis Risk in Communities (ARIC), Cardiovascular Health (CHS), Framingham Heart (FHS), and Health, Aging, and Body Compostion (Health ABC) studies.
We estimated the association of rs13038305 with eGFRcys and eGFRcr, and performed longitudinal analyses of the associations of eGFRcys with mortality and cardiovascular events following adjustment for rs13038305.
We assessed reclassification by genotype-adjusted eGFRcys across CKD categories: <45, 45–59, 60–89, and ≥90 mL/min/1.73 m2. We compared mortality and CVD outcomes in those reclassified to a worse eGFRcys category with those unaffected. Results were combined using fixed-effect inverse-variance meta-analysis.
In 14,645 participants, each copy of the T allele of rs13038305 (frequency, 21%), was associated with 6.4% lower cystatin C concentration, 5.5 mL/min/1.73 m2 higher eGFRcys, and 36% [95% CI, 29%–41%] lower odds of CKD. Associations with CVD (HR, 1.17; 95% CI, 1.14–1.20) and mortality (HR, 1.22; 95% CI, 1.19–1.24) per 10- ml/min/1.73 m2 lower eGFRcys were similar with or without rs13038305 adjustment. In total, 1134 participants (7.7%) were reclassified to a worse CKD category following rs13038305 adjustment, and rates of CVD and mortality were higher in individuals who were reclassified. However, the overall net reclassification index was not significant for either outcome, at 0.009 (95% CI, −0.003 to 0.022) for mortality and 0.014 (95% CI, 0.0 to 0.028) for CVD.
rs13038305 only explains a small proportion of cystatin C variation.
Statistical adjustment can correct a genetic bias in GFR estimates based on cystatin C in carriers of the T allele of rs13038305 and result in changes in disease classification. However, on a population level, the effects on overall reclassification of CKD status are modest.
Cystatin C; chronic kidney disease; genetics; single nucleotide polymorphism; net reclassification improvement
Higher serum cystatin C is associated with an increased risk of hip fracture in postmenopausal white women, but there is a paucity of data in men. Whether an estimated GFR (eGFR) based on cystatin C (eGFRcys) is superior in predicting hip fracture risk to an eGFR based on creatinine (eGFRcr) or the combination (eGFRcr-cys) is also uncertain.
Setting & Participants
Participants enrolled in the Osteoporotic Fractures in Men (MrOS) Study (5,994 men aged ≥65 years from six U.S. centers) including a random subcohort of 1602 men and 168 men with incident hip fractures (51 of whom were in the subcohort).
eGFRcys, eGFRcr and eGFRcr-cys computed using the CKD-EPI equations and expressed in categories of <60, 60–74, and ≥75 mL/min/l.73 m2 (referent group).
Incident hip fracture ascertained by participant contacts every 4 months and confirmed with radiographic reports.
Median eGFRcys was 72.9 (IQR, 60.5–85.7) mL/min/1.73 m2. In unadjusted models, all measures of eGFR were associated with increased hip fracture risk. However, after adjustment for age, race, site and BMI, the association of lower eGFRcys (but not lower eGFRcr or lower eGFRcr-cys) with higher hip fracture risk remained: for <60 vs. ≥75 mL/min/l.73 m2, HRs were 1.96 [95% CI, 1.25–3.09], 0.84 [95% CI, 0.52–1.37], and 1.08 [95% CI, 0.66–1.77] for eGFRcys, eGFRcr, and eGFRcr-cys, respectively. Similarly, after adjustment for age, race, site and BMI, eGFR of <60 ml/min/1.73 m2 defined by eGFRcys but not eGFRcr or eGFRcr-cys, was associated with higher hip fracture risk. The association between eGFRcys and hip fracture was not explained by levels of calcitropic hormones or inflammatory markers, but the relationship was attenuated and no longer reached significance (for <60 vs. ≥75 mL/min/l.73 m2: HR, 1.43; 95% CI, 0.88–2.34) after consideration of additional clinical risk factors and bone mineral density.
Findings not generalizable other populations; residual confounding may exist.
Older community-dwelling men with lower eGFRcys have an increased risk of hip fracture that is explained in large part by greater burden of risk factors among men with lower eGFRcys. In contrast, lower eGFRcr or lower eGFRcr-cys were not associated with a higher age-adjusted hip fracture risk.
kidney function; cystatin C; creatinine; hip fracture; elderly; men
To examine the association between kidney function and all-cause mortality in octogenarians.
Retrospective analysis of prospectively collected data.
Serum creatinine and cystatin C were measured in 1,053 Cardiovascular Health Study (CHS) All Stars participants.
Estimated glomerular filtration rate (eGFR) was determined using the Chronic Kidney Disease Epidemiology Collaboration creatinine (eGFRCR) and cystatin C one-variable (eGFRCYS) equations. The association between quintiles of kidney function and all-cause mortality was analyzed using unadjusted and adjusted Cox proportional hazards models.
Mean age of the participants was 85, 64% were female, 66% had hypertension, 14% had diabetes mellitus, and 39% had prevalent cardiovascular disease. There were 154 deaths over a median follow-up of 2.6 years. The association between eGFRCR and all-cause mortality was U-shaped. In comparison with the reference quintile (64–75 mL/min per 1.73 m2), the highest (≥75 mL/min per 1.73 m2) and lowest (≤43 mL/min per 1.73 m2) quintiles of eGFRCR were independently associated with mortality (hazard ratio (HR) = 2.49, 95% confidence interval (CI) = 1.36–4.55; HR = 2.28, 95% CI = 1.26–4.10, respectively). The association between eGFRCYS and all-cause mortality was linear in those with eGFRCYS of less than 60 mL/min per 1.73 m2, and in the multivariate analyses, the lowest quintile of eGFRCYS (<52 mL/min per 1.73 m2) was significantly associated with mortality (HR = 2.04, 95% CI = 1.12–3.71) compared with the highest quintile (>0.88 mL/min per 1.73 m2).
Moderate reduction in kidney function is a risk factor for all-cause mortality in octogenarians. The association between eGFRCR and all-cause mortality differed from that observed with eGFRCYS; the relationship was U-shaped for eGFRCR, whereas the risk was primarily present in the lowest quintile for eGFRCYS. J Am Geriatr Soc 2012.
octogenarians; kidney function; mortality
HIV-infected persons have substantially higher risk of kidney failure than persons without HIV, but serum creatinine levels are insensitive for detecting declining kidney function. We hypothesized that urine markers of kidney injury would be associated with declining kidney function among HIV-infected women.
In the Women's Interagency HIV Study (WIHS), we measured concentrations of albumin-to-creatinine ratio (ACR), interleukin-18 (IL-18), kidney injury marker-1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL) from stored urine among 908 HIV-infected and 289 uninfected participants. Primary analyses used cystatin C based estimated glomerular filtration rate (CKD-EPI eGFRcys) as the outcome, measured at baseline and two follow-up visits over eight years; secondary analyses used creatinine (CKD-EPI eGFRcr). Each urine biomarker was categorized into tertiles, and kidney decline was modeled with both continuous and dichotomized outcomes.
Compared with the lowest tertiles, the highest tertiles of ACR (−0.15ml/min/1.73m2, p<0.0001), IL-18 (−0.09ml/min/1.73m2, p<0.0001) and KIM-1 (−0.06ml/min/1.73m2, p<0.001) were independently associated with faster eGFRcys decline after multivariate adjustment including all three biomarkers among HIV-infected women. Among these biomarkers, only IL-18 was associated with each dichotomized eGFRcys outcome: ≥3% (Relative Risk 1.40; 95%CI 1.04-1.89); ≥5% (1.88; 1.30-2.71); and ≥10% (2.16; 1.20-3.88) for the highest versus lowest tertile. In alternative models using eGFRcr, the high tertile of KIM-1 had independent associations with 5% (1.71; 1.25-2.33) and 10% (1.78; 1.07-2.96) decline, and the high IL-18 tertile with 10% decline (1.97; 1.00-3.87).
Among HIV-infected women in the WIHS cohort, novel urine markers of kidney injury detect risk for subsequent declines in kidney function.
HIV; KIM-1; NGAL; IL-18; albumin-to-creatinine ratio; cystatin C; kidney injury
The role of host genetics in the development of subclinical atherosclerosis in the context of HIV infected persons who are being treated with highly active antiretroviral therapy (HAART) is not well understood.
The present genome-wide association study (GWAS) is based on 177 HIV-positive Caucasian males receiving HAART who participated in the Fat Redistribution and Metabolic Change in HIV Infection (FRAM) Study. Common and internal carotid intima-media thicknesses (cIMT) measured by B-mode ultrasound were used as a subclinical measure of atherosclerosis. Single nucleotide polymorphisms (SNPs) were assayed using the Illumina HumanCNV370-quad beadchip. Copy Number Variants (CNV) were inferred using a hidden Markov Model (PennCNV). Regression analyses were used to assess the association of common and internal cIMT with individual SNPs and CNVs, adjusting for age, duration of antiretroviral treatment, and principal components to account for potential population stratification.
Two SNPs in tight linkage disequilibrium, rs2229116 (a missense, nonsynonymous polymorphism (IIe to Val)) and rs7177922, located in the Ryanodine receptor (RYR3) gene on chromosome 15 were significantly associated with common cIMT (p-value<1.61×10−7). The RYR gene family has been known to play a role in the etiology of cardiovascular disease and has been shown to be regulated by HIV TAT protein.
These results suggest that in the context of HIV infection and HAART, a functional SNP in a biologically plausible candidate gene, RYR3, is associated with increased common carotid IMT, which is a surrogate for atherosclerosis.
HIV; HAART; atherosclerosis; GWAS; intima-media thickness
To investigate the effects of aging and smoking on carotid intima-media thickness (cIMT) among patients with and without HIV.
Data from a community sample of HIV-infected and HIV-uninfected participants were analyzed. Carotid intima-media thickness was measured via carotid ultrasound and smoking history was obtained via patient interview.
Data on 166male and female participants with stable HIV-infection and 152 healthy HIV-uninfected participants were analyzed. Among the HIV-infected and HIV-uninfected participants, a significant association was observed between age and cIMT [r=0.51, P<0.0001 (HIV), r=0.39, P<0.0001, (non-HIV)], and between smoking burden and cIMT [r=0.42, P<0.0001 (HIV), r=0.24, P=0.003 (non-HIV)]. In multivariate regression modeling among all participants (HIV and non-HIV), a significant three-way interaction was observed between age, smoking burden, and HIV status with respect to cIMT (P<0.010), controlling for gender, race and traditional cardiovascular disease (CVD) risk factors, such that increased cIMT was associated with increased smoking burden and age to a greater degree among HIV-infected vs. HIV-uninfected participants. Among HIV-infected participants a significant interaction between smoking burden and age with respect to cIMT was seen (P=0.027), controlling for race, gender, CVD risk factors, immunological function and antiretroviral therapy use.
A significant interaction between HIV, age and smoking on cIMT was observed, suggesting that HIV-infection modifies the relationship of age and smoking on cIMT in this population. These findings emphasize the need to encourage smoking cessation in this population, due to its deleterious effect on subclinical atherosclerosis in older HIV-infected patients.
HIV; Aging; Cardiovascular Diseases; Smoking
Chronic kidney disease risk factors may associate with the estimated glomerular filtration rate (eGFR) differently than with the measured GFR. To examine this, we evaluated 1150 patients (mean age 65) in two community cohorts for risk factors, measured GFR by iothalamate clearance, and eGFR based on creatinine (Cr), cystatin C (CysC), or both. The interaction between each risk factor and eGFR (relative to measured GFR) identified risk factor associations with eGFR along non-GFR pathways. In a subset of 40 patients with two visits, the mean coefficient of variation was 8.2% for measured GFR, 6.4% for eGFRCr, 8.2% for eGFRCr-CysC, and 10.7% for eGFRCysC. The measured GFR was better correlated with eGFRCr-CysC (r, 0.74) than eGFRCr (r, 0.70) or eGFRCysC (r, 0.68). Lower measured GFR associated with lower 24-hour urine creatinine, albuminuria, hypertension, diabetes, higher triglycerides, and higher uric acid. Lower eGFRCr had these same associations except for an association with higher 24-hour urine creatinine along a non-GFR pathway. Lower eGFRCysC and eGFRCr-CysC also had these same associations but also associated with obesity, albuminuria, hypertension, diabetes, higher triglycerides, higher C-reactive protein, and higher uric acid along non-GFR pathways. Thus, cystatin C improves estimation of GFR over creatinine alone; however, the association between most of the risk factors and GFR was more accurate by eGFR based on creatinine alone. This is explained by the association of these risk factors with the non-GFR determinants of cystatin C.
Obesity is associated with higher end-stage renal disease incidence, but associations with earlier forms of kidney disease remain incompletely characterized.
We studied the association of body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR) with rapid kidney function decline and incident chronic kidney disease in 4573 non-diabetic adults with eGFR ≥ 60 ml/min/1.73m2 at baseline from longitudinal Multi-Ethnic Study of Atherosclerosis cohort. Kidney function was estimated by creatinine and cystatin C. Multivariate analysis was adjusted for age, race, baseline eGFR, and hypertension.
Mean age was 60 years old, BMI 28 kg/m2, baseline eGFRCr 82 and eGFRCys 95 ml/min/1.73m2. Over 5 years of follow up, 25% experienced rapid decline in renal function by eGFRCr and 22% by eGFRCys. Incident chronic kidney disease (CKD) developed in 3.3% by eGFRCys, 11% by eGFRCr, and 2.4% by both makers. Compared to persons with BMI < 25, overweight (BMI 25 – 30) persons had the lowest risk of rapid decline by eGFRCr (0.84, 0.71 – 0.99). In contrast, higher BMI categories were associated with stepwise higher odds of rapid decline by eGFRCys, but remained significant only when BMI ≥ 35 kg/m2 (1.87, 1.41 – 2.48). Associations of BMI with incident CKD were insignificant after adjustment. Large WC and WHR were associated with increased risk of rapid decline only by eGFRCys, and of incident CKD only when defined by both filtration markers.
Obesity may be a risk factor for kidney function decline, but associations vary by filtration marker used.
Kidney Function Decline; MESA; Obesity; Waist Circumference; Waist-to-Hip Ratio
Defined as estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m2, chronic kidney disease (CKD) is strongly and independently associated with cardiovascular and overall mortality. We hypothesized that reduced kidney function would be characterized by abnormalities of hemostasis.
We tested cross-sectional associations between (eGFR) and multiple hemostatic markers among 6751 participants representing a broad spectrum of kidney function in the Multi-Ethnic Study of Atherosclerosis (MESA). Kidney function was measured using cystatin C (eGFRcys) or creatinine, using CKD Epidemiology Collaboration (eGFRcr). Hemostatic markers included soluble thrombomodulin (sTM), soluble tissue factor (sTF), D-Dimer, von Willebrand factor (vWF), factor VIII, plasmin-antiplasmin complex (PAP), tissue factor pathway inhibitor (TFPI), plasminogen activator inhibitor-1 (PAI-1), and fibrinogen. Associations were tested using multivariable linear regression with adjustment for demographics and comorbidities.
In comparison to persons with eGFRcys >90 ml/min/1.73 m2, subjects with eGFRcys < 60 ml/min/1.73 m2 had adjusted levels of sTM, sTF, D-Dimer, PAP, Factor VIII, TFPI, vWF and fibrinogen that were respectively 86%, 68%, 44%, 22%, 17%, 15%, 12% and 6% higher. Subjects with eGFRcys 60-90 ml/min/1.73 m2 had adjusted levels that were respectively 16%, 14%, 12%, 6%, 6%, 6%, 11% and 4% higher (p < 0.05 for all). Percent differences were not significantly different when groups were categorized by eGFRcr.
Throughout a broad spectrum of kidney function, lower eGFR was associated with higher levels of hemostatic markers. Dysregulation of hemostasis may be a mechanism by which reduced kidney function promotes higher cardiovascular risk.
HIV-infected patients may be at increased risk of cardiovascular (CV) events, and lipodystrophy is generally associated with proatherogenic metabolic disturbances. Carotid intima-media thickness (cIMT) has been used as a surrogate marker for atherosclerosis and it has been shown to be an independent risk factor for CV disease. Our objective was to evaluate cIMT in HIV-infected patients on combined anti-retroviral therapy (cART) with and without lipodystrophy defined by fat mass ratio (L-FMR), and to determine the association of lipodystrophy and visceral obesity [(visceral (VAT), subcutaneous adipose tissue (SAT) volume and VAT/SAT ratio, objectively evaluated by CT scan] with cIMT.
Cross-sectional study of 199 HIV-infected patients. Body composition by DXA and abdominal CT, lipids, blood pressure, inflammatory markers, and cIMT by ultrasonography were performed. L-FMR was defined as the ratio of the percentage of trunk fat mass to the percentage of lower limb fat mass by DXA. Categorical variables were compared using the chi-square or Fisher’s exact test. Spearman correlation coefficients were estimated to study the association between cIMT and clinical and metabolic characteristics. Means of cIMT, adjusted for age, were calculated, using generalized linear models.
L-FMR was present in 41.2% of patients and cIMT was higher in these patients [0.81 (0.24) vs. 0.76 (0.25); p = 0.037)]. Lipodystrophic patients had higher VAT and VAT/SAT ratio and lower SAT. cIMT was associated with lipodystrophy evaluated by FMR, trunk fat, total abdominal fat, VAT and VAT/SAT ratio. No association was observed between cIMT and leg fat mass. Using generalized linear models, cIMT means were adjusted for age and no significant differences remained after this adjustment. The adjusted mean of cIMT was 0.787 (95% CI: 0.751-0.823) in patients without lipodystrophy, and 0.775 (95% CI: 0.732-0.817) in those with lipodystrophy (p = 0.671).
HIV-infected patients on cART with lipodystrophy defined by FMR, had a significantly higher cIMT. Carotid IMT was also associated with classical cardiovascular risk factors. In these patients, visceral adipose tissue had a significant impact on cIMT, although age was the strongest associated factor.
Lipodystrophy; HIV; Carotid intima media thickness; Fat mass ratio; Body composition
Cardiovascular disease (CVD) is an increasing cause of morbidity and mortality in HIV-infected patients. However, it is controversial whether HIV infection contributes to accelerated atherosclerosis independent of traditional CVD risk factors.
Cross-sectional study of HIV-infected and control subjects without pre-existing CVD from the study of Fat Redistribution and Metabolic Change in HIV Infection (FRAM) and the Multi-Ethnic Study of Atherosclerosis (MESA). Pre-clinical atherosclerosis was assessed by carotid intima-medial thickness (IMT) measurements in the internal/bulb and common regions in HIV-infected and control subjects after adjusting for traditional CVD risk factors.
For internal carotid, mean IMT was 1.17±0.50mm for HIV-infected participants and 1.06±0.58mm for controls (p<0.0001). After multivariable adjustment for demographic characteristics, the mean difference of HIV-infected vs. controls was +0.188mm (95%CI 0.113-0.263, p<0.0001). Further adjustment for traditional CVD risk factors modestly attenuated the HIV association (+0.148mm, 95%CI 0.072-0.224, p=0.0001). For the common carotid, HIV infection was independently associated with greater IMT (+0.033mm, 95%CI 0.010, 0.056, p=0.005). The association of HIV infection with IMT was similar to that of smoking which was also associated with greater IMT (internal +0.173mm, common +0.020mm).
Even after adjustment for traditional CVD risk factors, HIV infection was accompanied by more extensive atherosclerosis measured by IMT. The stronger association of HIV infection with IMT in the internal/bulb region compared to the common carotid may explain previous discrepancies in the literature. The association of HIV infection with IMT was similar to that of traditional CVD risk factors, such as smoking.
HIV; carotid IMT; smoking; cholesterol; diabetes; atherosclerosis
Low birth weight has been shown to be associated with later renal function, but it is unclear to what extent this is explained by other established kidney disease risk factors. Here we investigate the roles of diabetes, hypertension, and obesity using data from the Medical Research Council National Survey of Health and Development, a socially stratified sample of 5362 children born in March 1946 in England, Scotland, and Wales, and followed since. The birth weight of 2192 study members with complete data was related to three markers of renal function at age 60–64 (estimated glomerular filtration rate (eGFR) calculated using cystatin C (eGFRcys), eGFR calculated using creatinine and cystatin C (eGFRcr-cys), and the urine albumin–creatinine ratio) using linear regression. Each 1 kg lower birth weight was associated with a 2.25 ml/min per 1.73 m2 (95% confidence interval 0.80–3.71) lower eGFRcys and a 2.13 ml/min per 1.73 m2 (0.69–3.58) lower eGFRcr-cys. There was no evidence of an association with urine albumin–creatinine ratio. These associations with eGFR were not confounded by socioeconomic position and were not explained by diabetes or hypertension, but there was some evidence that they were stronger in study members who were overweight in adulthood. Thus, our findings highlight the role of lower birth weight in renal disease and suggest that in those born with lower birth weight particular emphasis should be placed on avoiding becoming overweight.
birth weight; diabetes; estimated glomerular filtration rate; hypertension; kidney disease; obesity
Compared with controls, HIV-infected persons have a greater prevalence of kidney disease as assessed by high levels of cystatin C and albuminuria, but not as assessed by creatinine level. However, the clinical importance of elevated cystatin C and albuminuria in the HIV-infected population has not been studied.
We conducted an observational cohort study to determine the association of kidney disease (measured by albuminuria, cystatin C, and serum creatinine) with mortality.
Setting & Participants
922 HIV-infected persons enrolled in the FRAM (Fat Redistribution and Metabolic Change in HIV infection) study.
Serum cystatin C and serum creatinine were used to estimate glomerular filtration rate (eGFR). Albuminuria was defined as a positive urine dipstick (≥1+) or a urine albumin-creatinine ratio > 30 mg/g.
At baseline, reduced kidney function (eGFRSCysC <60 mL/min/1.73m2) or albuminuria was present in 28% of participants. After five years of follow-up, mortality was 48% among those with both eGFRSCysC <60 mL/min/1.73m2 and albuminuria, 23% in those with eGFRSCysC <60 mL/min/1.73m2 alone, 20% in those with albuminuria alone, and 9% in those with neither condition. After multivariable adjustment for demographics, cardiovascular risk factors, HIV-related factors, and inflammatory markers, eGFRSCysC <60 mL/min/1.73m2 and albuminuria were associated with nearly a twofold increase in mortality, whereas eGFRSCr <60 mL/min/1.73m2 did not appear to have any substantial association with mortality. Together, eGFRSCysC <60 mL/min/1.73m2 and albuminuria accounted for 17% of the population-level attributable risk for mortality.
Vital status was unknown in 261 participants from the original cohort.
Kidney disease marked by albuminuria or increased cystatin C levels appears to be an important risk factor for mortality in HIV-infected individuals. A substantial proportion of this risk may be unrecognized because of the current reliance on serum creatinine to estimate kidney function in clinical practice.
kidney disease; mortality; HIV infection
Serum cystatin C level has been shown to have a stronger association with clinical outcomes than serum creatinine level. However, little is known about the combined association of cystatin C–based estimated glomerular filtration rate (eGFRcys) and albuminuria with clinical outcomes, particularly at levels lower than current chronic kidney disease (CKD) cutoffs.
Setting & Participants
10,403 ARIC (Atherosclerosis Risk in Communities) Study participants followed up for a median of 10.2 years.
Mortality, coronary heart disease (CHD), and heart failure, as well as a composite of any of these separate outcomes.
Both decreased eGFRcys and albuminuria were associated independently with the composite outcome, as well as mortality, CHD, and heart failure. Although eGFRcys of 75-89 mL/min/1.73 m2 in the absence of albuminuria (albumin-creatinine ratio [ACR] <10 mg/g) or albuminuria with ACR of 10-29 mg/g with normal eGFRcys (90-104 mL/min/1.73 m2) was not associated significantly with any outcome compared with eGFRcys of 90-104 mL/min/1.73 m2 and ACR <10 mg/g, the risk of each outcome was significantly higher in those with both eGFRcys of 75-89 mL/min/1.73 m2 and ACR of 10-29 mg/g (for mortality, HR of 1.4 [95% CI, 1.1-2.0]; for CHD, HR of 1.9 [95% CI, 1.4-2.6]; for heart failure, HR of 1.8 [95% CI, 1.2-2.7]). Combining the 2 markers improved risk classification for all outcomes (P < 0.001), even in those without overt CKD.
Only one measurement of cystatin C.
Mildly decreased eGFRcys and mild albuminuria independently contributed to the risk of mortality, CHD, and heart failure. Even minimally decreased eGFRcys (75-89 mL/min/1.73 m2) is associated with increased risk in the presence of mild albuminuria. Combining the 2 markers is useful for improved risk stratification even in those without clinical CKD.
Epidemiology; kidney; outcomes
To determine the association of fetuin-A with subclinical CVD in community-living individuals.
Fetuin-A is a hepatic secretory protein that inhibits arterial calcium deposition in vitro. Lower fetuin-A levels are associated with arterial calcification and death in end-stage renal disease populations. The association of fetuin-A with subclinical cardiovascular disease (CVD) in the general population is unknown.
Among 1,375 community-living individuals without prevalent clinical CVD, we measured plasma fetuin-A concentrations measured by ELISA. Peripheral arterial disease (PAD) was defined by ankle brachial index (ABI) < 0.90, coronary artery calcification (CAC) was measured by computed tomography, and common and internal intima media thickness (cIMT) were measured by carotid ultrasound. PAD was measured concurrent with fetuin-A, and CAC and cIMT was measured 4.6 years (mean) later.
Mean age was 70 ± 11 years and 64% were female. Fetuin-A levels were inversely associated with CAC severity. When evaluated as CAC categories (0, 1–100, 101–300, > 300) using ordinal logistic regression, each standard deviation higher fetuin-A was associated with a 31% lower odds of CAC severity (proportional odds ratio [POR] 0.69; 95% confidence interval [CI] 0.46, 0.92; p=0.008) in models adjusted for demographics, lifestyle factors, traditional CVD risk factors and kidney function. In contrast, no association of fetuin-A was observed with PAD or high common or internal cIMT in adjusted models.
Lower fetuin-A levels are independently associated with greater CAC severity, but not PAD or cIMT. If confirmed, fetuin-A may mark calcium deposition within the vasculature, but not atherosclerosis per se.
Fetuin-A; Cardiovascular Disease; Coronary Artery Calcification
HIV-infected individuals have an increased risk of cardiovascular disease (CVD). T-allele carriers of the CD14 C-260T single-nucleotide polymorphism (SNP) have reported increased expression of the LPS-binding receptor, CD14 and inflammation in the general population. Our aim was to explore the relationship of this SNP with monocyte/macrophage activation and inflammation and its association with sub-clinical atherosclerosis in HIV-infected individuals.
Patients with no pre-existing CVD risk factors on suppressive antiretroviral therapy were recruited from University Malaya Medical Centre, Malaysia (n = 84). The CD14 C-260T and TLR4 SNPs, Asp299Gly and Thr399Ile were genotyped and soluble(s) CD14 and sCD163 and high-sensitivity C-reactive protein, hsCRP were measured in plasma. Subclinical atherosclerosis was assessed by measuring carotid intima media thickness (cIMT). The association between CD14 C-260T SNP carriage and cIMT was assessed in a multivariable quantile regression model where a p-value of <0.05 was considered significant.
We found the CD14 C-260T T-allele in 56% of the cohort and evidence of subclinical atherosclerosis in 27%. TT genotype was associated with higher sCD163 (p = 0.009) but only marginally higher sCD14 (p = 0.209) and no difference in hsCRP (p = 0.296) compared to CC/CT. In multivariable analysis, only Framingham risk score was independently associated with higher cIMT while lower sCD163 was trending towards significance. No association was found in TT-genotype carriers and cIMT measurements.
The CD14 C-260T SNP was associated with increased monocyte activation but not systemic inflammation or cIMT in this HIV-infected cohort with low CVD risk profile.
HIV; Lipopolysaccharide; CD12 C-260T; Soluble CD14; Soluble CD163; Monocyte activation; C-reactive protein; Atherosclerosis; Carotid intima media thickness
Chronic kidney disease (CKD) is associated with the incidence of cardiovascular disease. CKD may also increase the risk of atrial fibrillation (AF), but existing studies have reported inconsistent results.
Methods and Results
We estimated cystatin C-based glomerular filtration rate (eGFRcys) and measured urinary albumin-creatinine ratio (ACR) in 10,328 men and women free of AF from the Atherosclerosis Risk in Communities (ARIC) Study in 1996–98. Incidence of AF was ascertained through the end of 2007. During a median follow-up of 10.1 years, we identified 788 incident AF cases. Compared to individuals with eGFRcys ≥90 mL/min/1.73 m2, multivariable hazard ratios (HR) and 95% confidence intervals (CI) of AF were 1.3 (1.1–1.6), 1.6 (1.3–2.1), and 3.2 (2.0–5.0) (p for trend <0.0001) in those with eGFRcys of 60–89, 30–59 and 15–29 mL/min/1.73 m2, respectively. Similarly, presence of macroalbuminuria (ACR ≥300 mg/g, HR 3.2, 95% CI 2.3–4.5) and microalbuminuria (ACR 30–299 mg/g, HR 2.0, 95% CI 1.6–2.4) were associated with higher AF risk compared to those with ACR <30 mg/g. Risk of AF was particularly elevated in those with both low eGFRcys and macroalbuminuria (HR 13.1, 95% CI 6.0–28.6, comparing individuals with ACR≥300 mg/g and eGFRcys 15–29 vs. ACR<30 mg/g and eGFRcys ≥90 mL/min/1.73 m2).
In this large population-based study, reduced kidney function and presence of albuminuria were strongly associated with the incidence of AF independently of other risk factors.
Epidemiology; atrial fibrillation; kidney
Type 1 diabetes mellitus is associated with early atherosclerosis and enhanced cardiovascular mortality. The relationship between carotid IMT (cIMT), a marker of subclinical atherosclerosis and left ventricular (LV) mass, an independent predictor of cardiovascular morbidity has not been previously studied in type 1 diabetics.
The Epidemiology of Diabetes Interventions and Complications (EDIC) study is a multicenter observational study designed to follow up the Diabetes Control and Complications Trial (DCCT) cohort. LV mass was measured with cardiac MRI at EDIC year 15 and common cIMT was assessed using B-mode ultrasound at EDIC year 12. Multivariable linear regression models were used to assess the relationship between cIMT at year 12 and LV mass at year 15.
A total of 889 participants had both cardiac MRI and cIMT measures available for these analyses. At EDIC year 15, the mean age of the participants was 49 (±7) years; mean diabetes duration was 28 (±5) years and 52% were males. Spearman correlation coefficient (r) between LV mass and cIMT was 0.33 (p<0.0001). After adjusting for basic covariates (machine, reader, age and gender), a significant association between LV mass and cIMT (estimate 2.0 g/m2 per 0.1 mm cIMT increment, p < 0.0001) was observed. This association was diminished by the addition of systolic blood pressure in particular 1.15 g/m2 per 0.1 mm cIMT increment, p<0.0001) and to a lessor extent other cardiovascular disease (CVD) risk factors. The relationship observed between LV mass and cIMT was stronger (HOW MUCH) in patients with shorter diabetes duration.
In a well characterized population with type 1 diabetes, cIMT was an independent predictor of higher LV mass. These findings suggest a common pathway, possibly mediated by blood pressure dependent mechanisms, for vascular and myocardial structural change in T1DM.