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BackgroundNovel urine biomarkers have enabled the characterization of kidney tubular dysfunction and injury among persons living with HIV, a population at an increased risk of kidney disease. Even though several urine biomarkers predict progressive kidney function decline, antiretroviral toxicity, and mortality in the setting of HIV infection, the relationships among the risk factors for chronic kidney disease (CKD) and urine biomarkers are unclear.MethodsWe assessed traditional and infection-related CKD risk factors and measured 14 urine biomarkers at baseline and at follow-up among women living with HIV in the Women's Interagency Health Study (WIHS). We then used simultaneously adjusted multivariable linear regression models to evaluate the associations of CKD risk factors with longitudinal changes in biomarker levels.ResultsOf the 647 women living with HIV in this analysis, the majority (67%) were Black, the median age was 45 years and median follow-up time was 2.5 years. Each traditional and infection-related CKD risk factor was associated with a unique set of changes in urine biomarkers. For example, baseline hemoglobin a1c was associated with worse tubular injury (higher interleukin [IL]-18), proximal tubular reabsorptive dysfunction (higher α1-microglobulin), tubular reserve (lower uromodulin) and immune response to injury (higher chitinase-3-like protein-1 [YKL-40]). Furthermore, increasing hemoglobin a1c at follow-up was associated with further worsening of tubular injury (higher kidney injury molecule-1 [KIM-1] and IL-18), as well as higher YKL-40. HCV co-infection was associated with worsening proximal tubular reabsorptive dysfunction (higher β2-microglobulin [β2m]), and higher YKL-40, whereas HIV viremia was associated with worsening markers of tubular and glomerular injury (higher KIM-1 and albuminuria, respectively).ConclusionsCKD risk factors are associated with unique patterns of biomarker changes among women living with HIV, suggesting that serial measurements of multiple biomarkers may help in detecting and monitoring kidney disease in this setting.

Rationale & objectiveSingle measurements of urinary biomarkers reflecting kidney tubule health are associated with chronic kidney disease (CKD) risk in HIV infection, but the prognostic value of repeat measurements over time is unknown.Study designCohort study.Setting & participants647 women living with HIV infection enrolled in the Women's Interagency Health Study.Exposures14 urinary biomarkers of kidney tubule health measured at 2 visits over a 3-year period.OutcomeIncident CKD, defined as estimated glomerular filtration rate (eGFR)

ObjectivesUrinary biomarkers of kidney injury may have potential to identify subclinical injury attributable to tenofovir disoproxil fumarate (TDF) toxicity.DesignThis observational study included 198 HIV-infected participants from the Multicenter AIDS Cohort Study and the Women's Interagency HIV Study, who initiated TDF between 2009 and 2015 and had urine samples collected at baseline before and after TDF initiation.MethodsWe used linear mixed-effects models controlling for urine creatinine and time on TDF to evaluate the effects of TDF initiation on changes in 14 urinary biomarkers.ResultsWithin 1 year after TDF initiation, concentrations of trefoil factor 3 [+78%; 95% confidence interval (CI) +38%, +129%), alpha-1 microglobulin (α1m) (+32%; 95% CI +13%, +55%), clusterin (+21%; 95% CI +6%, +38%), uromodulin (+19%; 95% CI +4%, +36%), and kidney injury molecule-1 (KIM-1) (+13%; 95% CI +1%, +26%) significantly increased, whereas interleukin-18 (IL-18) significantly decreased (-13%, 95% CI -7%, -25%). Subsequent to the first year of TDF use, biomarker concentrations stabilized, and these changes were not statistically significant. When stratifying by baseline viremia (HIV-1 RNA < vs. ≥80 copies/ml), concentration changes for most biomarkers during the first year of TDF use were greater among aviremic vs. viremic participants, with significant differences in α1m (+80 vs. +22%), KIM-1 (+43 vs. +10%), beta-2 microglobulin (+83 vs. -10%), YKL-40 (+33 vs. -5%), and IL-18 (+20 vs. -27%).ConclusionsTDF initiation was associated with substantial changes in urinary biomarkers of kidney injury within the first year of use, particularly among aviremic participants. A urinary biomarker panel may be a clinically useful tool to detect and monitor the heterogeneous effects of TDF on the kidney.

BACKGROUND:HIV-infected (HIV+) persons are at increased risk of chronic kidney disease, but serum creatinine does not detect early losses in kidney function. We hypothesized that urine biomarkers of kidney damage would be associated with subsequent changes in kidney function in a contemporary cohort of HIV+ and HIV-uninfected (HIV-) men. METHODS:In the Multicenter AIDS Cohort Study, we measured baseline urine concentrations of 5 biomarkers from 2009 to 2011 in 860 HIV+ and 337 HIV- men: albumin, alpha-1-microglobulin (α1m), interleukin-18 (IL-18), kidney injury molecule-1 (KIM-1), and procollagen type III N-terminal propeptide (PIIINP). We evaluated associations of urine biomarker concentrations with annual changes in estimated glomerular filtration rate (eGFR) using multivariable linear mixed models adjusted for demographics, traditional kidney disease risk factors, HIV-related risk factors, and baseline eGFR. RESULTS:Over a median follow-up of 4.8 years, the average annual eGFR decline was 1.42 mL/min/1.73 m2/year in HIV+ men and 1.22 mL/min/1.73 m2/year in HIV- men. Among HIV+ men, the highest vs. lowest tertiles of albumin (-1.78 mL/min/1.73 m2/year, 95% CI -3.47 to -0.09) and α1m (-2.43 mL/min/1.73 m2/year, 95% CI -4.14 to -0.73) were each associated with faster annual eGFR declines after multivariable adjustment. Among HIV- men, the highest vs. lowest tertile of α1m (-2.49 mL/min/1.73 m2/year, 95% CI -4.48 to -0.50) was independently associated with faster annual eGFR decline. Urine IL-18, KIM-1, and PIIINP showed no independent associations with eGFR decline, regardless of HIV serostatus. CONCLUSIONS:Among HIV+ men, higher urine albumin and α1m are associated with subsequent declines in kidney function, independent of eGFR.

ObjectiveDiabetes and hypertension, common conditions in antiretroviral-treated HIV-infected individuals, are associated with glomerular hyperfiltration, which precedes the onset of proteinuria and accelerated kidney function decline. In the Multicenter AIDS Cohort Study, we examined the extent to which hyperfiltration is present and associated with metabolic, cardiovascular, HIV and treatment risk factors among HIV-infected men.DesignCross-sectional cohort using direct measurement of glomerular filtration rate by iohexol plasma clearance for 367 HIV-infected men and 241 HIV-uninfected men who were free of chronic kidney disease.MethodsHyperfiltration was defined as glomerular filtration rate above 140-1 ml/min per 1.73 m per year over age 40. Multivariate logistic regression was used to estimate the odds ratios (ORs) of prevalent hyperfiltration for metabolic, cardiovascular, HIV and cumulative antiretroviral exposure factors.ResultsAmong individuals without chronic kidney disease, the prevalence of hyperfiltration was higher for HIV-infected participants (25%) compared to uninfected participants (17%; P = 0.01). After adjustment, HIV infection remained associated with hyperfiltration [OR 1.70, 95% confidence interval (CI) 1.11-2.61] and modified the association between diabetes and hyperfiltration, such that the association among HIV-uninfected men (OR 2.56, 95% CI 1.33-5.54) was not observed among HIV-infected men (OR 1.19, 95% CI 0.69-2.05). These associations were independent of known risk factors for hyperfiltration. Indicators of hyperglycemia and hypertension were also associated with hyperfiltration as was cumulative zidovudine exposure.ConclusionHyperfiltration, a potential modifiable predictor of kidney disease progression, is significantly higher among antiretroviral-treated HIV-infected men. Furthermore, HIV-infection nullifies the association of diabetes and hyperfiltration present in HIV-uninfected men.

Because dementia is progressive, incident cases are on average milder than prevalent cases, affecting the performance of cognitive tests and questions on functional limitations (i.e. cognition/functional limitation items) used for dementia assessment. Longitudinal studies assess incident cases, while cross-sectional studies assess prevalent cases, but differences are not typically considered when researchers select items to include in studies. We used longitudinal data from the Religious Orders Study and Memory and Aging Project (ROSMAP) (n  = 3,446) collected between 1994 and 2021 to characterize differences in associations between items (cognition: 35 items; functional limitations: 14 items) and incident or prevalent dementia using multinomial regression models with generalized estimating equations, controlling for ROSMAP cohort (Religious Orders Study or Memory and Aging Project), age, sex, race, and education. The association between a given item and incident dementia was significantly weaker than the association between the same item and prevalent dementia for 46 of 49 items. However, there was variability, with larger differences for some items, including naming a pencil (prevalence odds ratio = 0.02 (95% confidence interval: 0.02, 0.03); incidence odds ratio = 0.10 (95% confidence interval: 0.06, 0.17); P for difference < 0.001). Important differences exist in the performance of cognition/functional limitation items for measurement of incident versus prevalent dementia. Differences can inform the choice of items for cross-sectional studies of prevalent cases or longitudinal studies of incident cases, leading to reduced misclassification and increased statistical power. [ABSTRACT FROM AUTHOR]

Background: Ambulatory blood pressure monitoring (ABPM) is routinely performed in children with chronic kidney disease to identify masked hypertension, a risk factor for accelerated chronic kidney disease progression. However, ABPM is burdensome, and developing an accurate prediction of masked hypertension may allow using ABPM selectively rather than routinely.Methods: To create a prediction model for masked hypertension using clinic blood pressure (BP) and other clinical characteristics, we analyzed 809 ABPM studies with nonhypertensive clinic BP among the participants of the Chronic Kidney Disease in Children study.Results: Masked hypertension was identified in 170 (21.0%) observations. We created prediction models for masked hypertension via gradient boosting, random forests, and logistic regression using 109 candidate predictors and evaluated its performance using bootstrap validation. The models showed C statistics from 0.660 (95% CI, 0.595-0.707) to 0.732 (95% CI, 0.695-0.786) and Brier scores from 0.148 (95% CI, 0.141-0.154) to 0.167 (95% CI, 0.152-0.183). Using the possible thresholds identified from this model, we stratified the dataset by clinic systolic/diastolic BP percentiles. The prevalence of masked hypertension was the lowest (4.8%) when clinic systolic/diastolic BP were both <20th percentile, and relatively low (9.0%) with clinic systolic BP<20th and diastolic BP<80th percentiles. Above these thresholds, the prevalence was higher with no discernable pattern.Conclusions: ABPM could be used selectively in those with low clinic BP, for example, systolic BP<20th and diastolic BP<80th percentiles, although careful assessment is warranted as masked hypertension was not completely absent even in this subgroup. Above these clinic BP levels, routine ABPM remains recommended. [ABSTRACT FROM AUTHOR]

The assessment of aflatoxin B1 (AFB1) exposure using isotope-dilution liquid chromatography-mass spectrometry (LCMS) of AFB1-lysine adducts in human serum albumin (HSA) has proven to be a highly productive strategy for the biomonitoring of AFB1 exposure. To compare samples across different individuals and settings, the conventional practice has involved the normalization of raw AFB1-lysine adduct concentrations (e.g., pg/mL serum or plasma) to the total circulating HSA concentration (e.g., pg/mg HSA). It is hypothesized that this practice corrects for technical error, between-person variance in HSA synthesis or AFB1 metabolism, and other factors. However, the validity of this hypothesis has been largely unexamined by empirical analysis. The objective of this work was to test the concept that HSA normalization of AFB1-lysine adduct concentrations effectively adjusts for biological and technical variance and improves AFB1 internal dose estimates. Using data from AFB1-lysine and HSA measurements in 763 subjects, in combination with regression and Monte Carlo simulation techniques, we found that HSA accounts for essentially none of the between-person variance in HSA-normalized (R2 = 0.04) or raw AFB1-lysine measurements (R2 = 0.0001), and that HSA normalization of AFB1-lysine levels with empirical HSA values does not reduce measurement error any better than does the use of simulated data (n = 20,000). These findings were robust across diverse populations (Guatemala, China, Chile), AFB1 exposures (105 range), HSA assays (dye-binding and immunoassay), and disease states (healthy, gallstones, and gallbladder cancer). HSA normalization results in arithmetic transformation with the addition of technical error from the measurement of HSA. Combined with the added analysis time, cost, and sample consumption, these results suggest that it may be prudent to abandon the practice of normalizing adducts to HSA concentration when measuring any HSA adducts—not only AFB1-lys adducts—when using LCMS in serum/plasma. [ABSTRACT FROM AUTHOR]

[Figure: see text]. [ABSTRACT FROM AUTHOR]

Background A simple equation for glomerular filtration rate (GFR) measurement based on only plasma samples during the slow compartment after injection of iohexol was previously developed among children with chronic kidney disease and adult men with or at risk of HIV infection [Chronic Kidney Disease in Children (CKiD)-Multicenter AIDS Cohort Study (MACS) equation], but has not been externally validated. We aimed to evaluate the performance of the CKiD-MACS equation among elderly participants in the Multi-Ethnic Study of Atherosclerosis (MESA) cohort who underwent directly measured iohexol GFR. Methods Using data from 287 participants of the MESA-Kidney study who underwent a five-sample measured iohexol GFR (two and three samples in the fast and slow compartments, respectively), we assessed the performance of the CKiD-MACS equation using only plasma samples in the slow compartment by sex, race and age. Agreement was assessed by bias, correlation, proportion within 5 and 10%, and the root mean square error (RMSE). Results The average age and GFR of the participants were 71 years and 70.8 mL/min/1.73 m2, respectively, and 46% were black. The equation yielded excellent agreement within stratified groups with high correlation (>0.96), low bias (≤1.2 mL/min/1.73 m2) and low RMSE (<4.2 mL/min/1.73 m2). Conclusions The CKiD-MACS equation demonstrated valid GFR measurement using only samples in the slow compartment in this racially diverse, elderly population. While the equation yielded practically the same results as the original Brochner-Mortensen equation, the CKiD-MACS equation conforms to theoretical principles embedded in the two-compartment model of direct GFR measurement. [ABSTRACT FROM AUTHOR]