Mediation analysis of chronic kidney disease risk factors using kidney biomarkers in women living with HIV

OBJECTIVE

Novel urinary biomarkers reflecting kidney tubule health are associated with chronic kidney disease (CKD) risk in persons living with HIV. However, it is unknown whether these biomarkers provide mechanistic insight into the associations between clinical risk factors for CKD and subsequent CKD risk.

METHODS

Among 636 women living with HIV in the Women's Interagency HIV Study with estimated glomerular filtration rate (eGFR) >60 ml/min/1.73 m 2 , we used a counterfactual approach to causal mediation analysis to evaluate the extent to which systolic blood pressure (SBP), diastolic blood pressure (DBP), hemoglobin a1c (Hba1c) and serum albumin associations with incident CKD were mediated by eight urine proteins. These biomarkers reflect proximal tubular reabsorptive dysfunction (α1-microglobulin [a1m], β2-microglobulin, trefoil factor 3); tubular injury (interleukin 18 [IL-18], kidney injury molecule 1 [KIM-1]); kidney repair (epidermal growth factor); tubular reserve (uromodulin); and glomerular injury (urinary albumin). Incident CKD was defined as eGFR <60 ml/min/1.73 m 2 measured at two consecutive 6-month visits with an average annual eGFR decline ≥3% per year.

RESULTS

During a median follow-up of 7 years, 11% developed CKD. Urinary albumin and KIM-1 mediated 32% (95% CI: 13.4%, 76.6%) and 23% (6.9%, 60.7%) of the association between SBP and incident CKD, respectively; and 19% (5.1%, 42.3%) and 22% (8.1%, 45.7%) of the association between DBP and incident CKD, respectively. Urinary albumin, α1m, and IL-18 were significant mediators of the association between Hba1c and incident CKD. None of the eight biomarkers mediated the association between serum albumin and incident CKD.

CONCLUSIONS

Among women living with HIV, several urinary biomarkers reflecting distinct dimensions of kidney health may partially explain the associations between SBP, DBP, and Hba1c and subsequent CKD risk.

Changes in Natriuretic Peptide Levels and Subsequent Kidney Function Decline in SPRINT

RATIONALE & OBJECTIVE

Novel approaches to the assessment of kidney disease risk during hypertension treatment are needed because of the uncertainty of how intensive blood pressure (BP) lowering impacts kidney outcomes. We determined whether longitudinal N-terminal pro-B-type natriuretic peptide (NT-proBNP) measurements during hypertension treatment are associated with kidney function decline.

STUDY DESIGN

Prospective observational study.

SETTING & PARTICIPANTS

8,005 SPRINT (Systolic Blood Pressure Intervention Trial) participants with NT-proBNP measurements at baseline and 1 year.

EXPOSURE

1-year change in NT-proBNP categorized as a ≥25% decrease, ≥25% increase, or <25% change (stable).

OUTCOME

Annualized change in estimated glomerular filtration rate (eGFR) and ≥30% decrease in eGFR.

ANALYTICAL APPROACH

Linear mixed-effect and logistic regression models were used to evaluate the association of changes in NT-proBNP with subsequent annualized change in eGFR and ≥30% decrease in eGFR, respectively. Analyses were stratified by baseline chronic kidney disease (CKD) status.

RESULTS

Compared with stable 1-year NT-proBNP levels, a ≥25% decrease in NT-proBNP was associated with a slower decrease in eGFR in participants with CKD (adjusted difference, 1.09%/y; 95% CI, 0.35-1.83) and without CKD (adjusted difference, 0.51%/y; 95% CI, 0.21-0.81; P = 0.4 for interaction). Meanwhile, a ≥25% increase in NT-proBNP in participants with CKD was associated with a faster decrease in eGFR (adjusted difference, -1.04%/y; 95% CI, -1.72 to -0.36) and risk of a ≥30% decrease in eGFR (adjusted odds ratio, 1.44; 95% CI, 1.06-1.96); associations were stronger in participants with CKD than in participants without CKD (P = 0.01 and P < 0.001 for interaction, respectively). Relationships were similar irrespective of the randomized BP arm in SPRINT (P > 0.2 for interactions).

LIMITATIONS

Persons with diabetes and proteinuria >1 g/d were excluded.

CONCLUSIONS

Changes in NT-proBNP during BP treatment are independently associated with subsequent kidney function decline, particularly in people with CKD. Future studies should assess whether routine NT-proBNP measurements may be useful in monitoring kidney risk during hypertension treatment.

PLAIN-LANGUAGE SUMMARY

N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a biomarker in the blood that reflects mechanical stress on the heart. Measuring NT-proBNP may be helpful in assessing the risk of long-term losses of kidney function. In this study, we investigated the association of changes in NT-proBNP with subsequent kidney function among individuals with and without chronic kidney disease. We found that increases in NT-proBNP are associated with a faster rate of decline of kidney function, independent of baseline kidney measures. The associations were more pronounced in individuals with chronic kidney disease. Our results advance the notion of considering NT-proBNP as a dynamic tool for assessing kidney disease risk.

Associations of ambulatory blood pressure measurements with high-sensitivity troponin and natriuretic peptide levels in SPRINT

BACKGROUND

Nighttime blood pressure (BP) has greater prognostic importance for cardiovascular disease (CVD) than daytime BP, but less is known about nighttime and daytime BP associations with measures of subclinical CVD.

METHODS

Among 897 Systolic Blood Pressure Intervention Trial Study (SPRINT) participants with 24-hour ambulatory BP monitoring obtained near the 27-month study visit, 849 (95%) had N-terminal pro-B-type natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponin T (hs-cTnT) measured at the 24-month study visit. Multivariable linear regression analyses were performed to evaluate the associations of nighttime and daytime BP with cardiac biomarker levels.

RESULTS

Mean age was 69 ±12 years, 28% were African American, and mean nighttime and daytime SBP were 121 ±16 mm Hg and 132 ±14 mm Hg, respectively. In multivariable models, compared with the lowest tertile of nighttime systolic BP, the highest tertile was associated with 48% higher NT-proBNP levels (adjusted geometric mean ratio [GMR] = 1.48, 95% CI: 1.22, 1.79), and 19% higher hs-cTnT levels (adjusted GMR = 1.19, 95% CI: 1.07, 1.32). In contrast, the highest versus lowest tertile of daytime systolic BP was not associated with NT-proBNP (adjusted GMR = 1.09, 95% CI: 0.88, 1.34) but was associated with 16% higher hs-cTnT levels (adjusted GMR = 1.16, 95% CI: 1.04, 1.30). Similar results were observed using diastolic BP.

CONCLUSION

In SPRINT, both higher nighttime and daytime BP were independently associated with higher hs-cTnT levels, but only higher nighttime BP was associated with higher NT-proBNP levels.

Intensive Blood Pressure Lowering in Individuals With Low Diastolic Blood Pressure and Elevated Troponin Levels in SPRINT

BACKGROUND

Among individuals with hypertension and low diastolic blood pressure (DBP), the optimal BP target remains controversial due to concerns that BP lowering may reduce coronary perfusion. We determined the impact of intensive BP control among individuals with elevated systolic BP who have low DBP and elevated hs-cTnT (high-sensitivity cardiac troponin T) levels.

METHODS AND RESULTS

A total of 8828 participants in SPRINT (Systolic Blood Pressure Intervention Trial) were stratified by baseline DBP. Those with low DBP (<70 mm Hg) were further stratified by elevated hs-cTnT (≥14 ng/L) at baseline. The effects of intensive versus standard BP lowering on a cardiovascular disease composite end point, all-cause death, and 1-year change in hs-cTnT were determined. The combination of low DBP/high hs-cTnT was independently associated with a higher risk for cardiovascular disease and all-cause death, as well as greater 1-year increases in hs-cTnT, compared with DBP ≥70 mm Hg. However, randomization to intensive versus standard BP lowering led to similar reductions in cardiovascular disease risk among individuals with low DBP/high hs-cTnT (hazard ratio [HR], 0.82 [95% CI, 0.57-1.19]), low DBP/low hs-cTnT (HR, 0.48 [95% CI, 0.29-0.79]), and DBP ≥70 mm Hg (HR, 0.73 [95% CI, 0.60-0.89]; P for interaction=0.20). Intensive BP lowering also led to a reduction in all-cause death that was similar across groups (P for interaction=0.57).

CONCLUSIONS

In this nonprespecified subgroup analysis of SPRINT, individuals with low DBP and elevated hs-cTnT, low DBP and nonelevated hs-cTnT, and DBP ≥70 mm Hg derived similar cardiovascular disease and mortality benefits from intensive BP lowering. These findings warrant confirmation in other studies.

High-Sensitivity Cardiac Troponins I and T and Cardiovascular Outcomes: Findings from the Systolic Blood Pressure Intervention Trial (SPRINT)

BACKGROUND

Cardiac troponins are associated with adverse cardiovascular disease (CVD) outcomes. The value of high-sensitivity cardiac troponin I (hs-cTnI) independently and in concert with troponin T (hs-cTnT) in the management of hypertension has not been well studied.

METHODS

We assessed the utility of hs-cTnI independently and with hs-cTnT in identifying the highest risk individuals in the Systolic Blood Pressure Intervention Trial (SPRINT). Among 8796 eligible SPRINT participants, hs-cTnI was measured at baseline and 1 year. The association of baseline level and 1-year change in hs-cTnI with CVD events and all-cause death was evaluated using adjusted Cox regression models. We further assessed the complementary value of hs-cTnI and hs-cTnT by identifying concordant and discordant categories and assessing their association with outcomes.

RESULTS

hs-cTnI was positively associated with composite CVD risk [myocardial infarction, other acute coronary syndrome, stroke, or cardiovascular death: hazard ratio 1.23, 95% confidence interval 1.08-1.39 per 1-unit increase in log(troponin I)] independent of traditional risk factors, N-terminal pro-B-type natriuretic peptide, and hs-cTnT. Intensive blood pressure lowering was associated with greater absolute risk reduction (4.5% vs 1.7%) and lower number needed to treat (23 vs 59) for CVD events among those with higher baseline hs-cTnI (≥6 ng/L in men, ≥4 ng/L in women). hs-cTnI increase at 1 year was also associated with increased CVD risk. hs-cTnI and hs-cTnT were complementary, and elevations in both identified individuals with the highest risk for CVD and death.

CONCLUSIONS

Baseline levels and change in hs-cTnI over 1 year identified higher-risk individuals who may derive greater cardiovascular benefit with intensive blood pressure treatment. hs-TnI and hs-TnT have complementary value in CVD risk assessment. ClinicalTrials.gov Registration Number: NCT01206062.

Does haste make waste? Prevalence and types of errors reported after publication of studies of COVID-19 therapeutics

BACKGROUND

The COVID-19 pandemic spurred publication of a rapid proliferation of studies on potential therapeutic agents. While important for the advancement of clinical care, pressure to collect, analyze, and report data in an expedited manner could potentially increase the rate of important errors, some of which would be captured in published errata. We hypothesized that COVID-19 therapeutic studies published in the early years of the pandemic would be associated with a high rate of published errata and that, within these errata, there would be a high prevalence of serious errors.

METHODS

We performed a review of published errata associated with empirical studies of COVID-19 treatments. Errata were identified via a MEDLINE and Embase search spanning January 2020 through September 2022. Errors located within each published erratum were characterized by location within publication, error type, and error seriousness.

RESULTS

Of 47 studies on COVID-19 treatments with published errata, 18 met inclusion criteria. Median time from publication of the original article to publication of the associated erratum was 76 days (range, 12-511 days). A majority of errata addressed issues with author attribution or conflict of interest disclosures (39.5%) or numerical results (25.6%). Only one erratum contained a serious error: a typographical error which could have misled readers into believing that the treatment in question had serious adverse effects when in fact it did not.

CONCLUSIONS

Despite accelerated publication times, we found among studies of COVID-19 treatments the majority of errata (17/18) reported minor errors that did not lead to misinterpretation of the study results. Retractions, an indicator of scientific misdirection even more concerning than errata, were beyond the scope of this review.

Markers of Kidney Tubule Dysfunction and Major Adverse Kidney Events

BACKGROUND

Serum creatinine and albuminuria are primary markers of glomerular function and injury, respectively. Tubular secretion, acid-base homeostasis, protein reabsorption, among other tubular functions, are largely ignored. This mini-review aimed to discuss how two tubular functions, secretion, and acid-base homeostasis are associated with major adverse kidney events (MAKEs).

SUMMARY

Proximal tubular secretion is an essential function that allows the elimination of endogenous substances and drugs. Recently discovered endogenous markers in urine and plasma allow a noninvasive way of assessing tubular secretion markers. Several studies have found an association between these markers and a higher risk of chronic kidney disease (CKD) progression and mortality. In a study we recently performed among patients with CKD and at risk of cardiovascular events, lower tubular secretion was associated with an increased risk of acute kidney injury and metabolic acidosis, independent of baseline eGFR and albuminuria. The kidney tubules also play a crucial role in acid-base homeostasis. Although the standard clinical assessment of acidosis consists of measuring serum bicarbonate, urinary ammonium excretion decreases before over metabolic acidosis. Urinary ammonium excretion is associated with CKD progression, a higher risk of kidney failure, and an increased mortality risk, independent of baseline eGFR and albuminuria.

KEY MESSAGES

Novel biomarkers of kidney tubular health consistently associate with MAKEs, above and beyond baseline eGFR, albuminuria, and other CKD risk factors. Tubular markers may provide new opportunities to improve kidney prognosis, drug dosing, and monitoring for adverse events.

Effect of Intensive Blood Pressure Control on Troponin and Natriuretic Peptide Levels: Findings From SPRINT

BACKGROUND

Given the important role of cardiac injury and neurohormonal activation in the pathways leading from hypertension to heart failure and strong associations observed between hypertension and its sequelae on hs-cTnT (high-sensitivity cardiac troponin T) and NT-proBNP (N-terminal pro-B-type natriuretic peptide) levels, we hypothesized that intensive systolic blood pressure (SBP) lowering would decrease levels of hs-cTnT and NT-proBNP.

METHODS

hs-cTnT and NT-proBNP were measured at baseline and 1 year from stored specimens in SPRINT (Systolic Blood Pressure Intervention Trial). Changes in biomarkers were evaluated continuously on the log scale and according to categories (≥50% increase, ≥50% decrease, or <50% change). The effect of intensive SBP lowering on continuous and categorical changes in biomarker levels were assessed using linear and multinomial logistic regression models, respectively. The association between changes in biomarkers on heart failure and death was assessed using multivariable-adjusted Cox proportional hazards models.

RESULTS

Randomization to intensive SBP lowering (versus standard SBP management) resulted in a 3% increase in hs-cTnT levels over 1-year follow-up (geometric mean ratio, 1.03 [95% CI, 1.01-1.04]) and a higher proportion of participants with ≥50% increase (odds ratio, 1.47 [95% CI, 1.13, 1.90]). In contrast, randomization to intensive SBP lowering led to a 10% decrease in NT-proBNP (geometric mean ratio, 0.90 [95% CI, 0.87-0.93]) and a lower probability of ≥50% increase in NT-proBNP (odds ratio, 0.57 [95% CI, 0.46-0.72]). The association of randomized treatment assignment on change in hs-cTnT was completely attenuated after accounting for changes in estimated glomerular filtration rate over follow-up, whereas the association of treatment with NT-proBNP was completely attenuated after adjusting for change in SBP. Increases in hs-cTnT and NT-proBNP from baseline to 1 year were associated with higher risk for heart failure and death, with no significant interactions by treatment assignment.

CONCLUSIONS

Intensive SBP lowering increased hs-cTnT, mediated by the effect of SBP lowering on reduced kidney filtration. In contrast, intensive SBP lowering decreased NT-proBNP, a finding that was explained by the decrease in SBP. These findings highlight the importance of noncardiac factors influencing variation in cardiac biomarkers and raise questions about the potential role of hs-cTnT as a surrogate marker for heart failure or death in SBP-lowering studies.

Intensive Blood Pressure Lowering in Patients With Malignant Left Ventricular Hypertrophy

BACKGROUND

Left ventricular hypertrophy (LVH) combined with elevations in cardiac biomarkers reflecting myocardial injury and neurohormonal stress (malignant LVH) is associated with a high risk for heart failure and death.

OBJECTIVES

The aim of this study was to determine the impact of intensive systolic blood pressure (SBP) control on the prevention of malignant LVH and its consequences.

METHODS

A total of 8,820 participants in SPRINT (Systolic Blood Pressure Intervention Trial) were classified into groups based on the presence or absence of LVH assessed by 12-lead ECG, and elevations in biomarker levels (high-sensitivity cardiac troponin T ≥14 ng/L or N-terminal pro-B-type natriuretic peptide ≥125 pg/mL) at baseline. The effects of intensive vs standard SBP lowering on rates of acute decompensated heart failure (ADHF) events and death and on the incidence and regression of malignant LVH were determined.

RESULTS

Randomization to intensive SBP lowering led to similar relative reductions in ADHF events and death across the combined LVH/biomarker groups (P for interaction = 0.68). The absolute risk reduction over 4 years in ADHF events and death was 4.4% (95% CI: -5.2% to 13.9%) among participants with baseline malignant LVH (n = 449) and 1.2% (95% CI: 0.0%-2.5%) for those without LVH and nonelevated biomarkers (n = 4,361). Intensive SBP lowering also reduced the incidence of malignant LVH over 2 years (2.5% vs 1.1%; OR: 0.44; 95% CI: 0.30-0.63).

CONCLUSIONS

Intensive SBP lowering prevented malignant LVH and may provide substantial absolute risk reduction in the composite of ADHF events and death among SPRINT participants with baseline malignant LVH.

Markers of Kidney Tubular Secretion and Risk of Adverse Events in SPRINT Participants with CKD

BACKGROUND

Kidney tubular secretion is an essential mechanism for clearing many common antihypertensive drugs and other metabolites and toxins. It is unknown whether novel measures of tubular secretion are associated with adverse events (AEs) during hypertension treatment.

METHODS

Among 2089 SPRINT (Systolic Blood Pressure Intervention Trial) participants with baseline eGFR <60 ml/min per 1.73 m2, we created a summary secretion score by averaging across the standardized spot urine-to-plasma ratios of ten novel endogenous tubular secretion measures, with lower urine-to-plasma ratios reflecting worse tubular secretion. Multivariable Cox proportional hazards models were used to evaluate associations between the secretion score and risk of a composite of prespecified serious AEs (hypotension, syncope, bradycardia, AKI, electrolyte abnormalities, and injurious falls). The follow-up protocol for SPRINT routinely assessed two laboratory monitoring AEs (hyperkalemia and hypokalemia).

RESULTS

Overall, 30% of participants experienced at least one AE during a median follow-up of 3.0 years. In multivariable models adjusted for eGFR and albuminuria, lower (worse) secretion scores at baseline were associated with greater risk of the composite AE outcome (hazard ratio per 1-SD lower secretion score, 1.16; 95% confidence interval, 1.04 to 1.27). In analyses of the individual AEs, lower secretion score was associated with significantly greater risk of AKI, serious electrolyte abnormalities, and ambulatory hyperkalemia. Associations were similar across randomized treatment assignment groups.

CONCLUSION

Among SPRINT participants with CKD, worse tubular secretion was associated with greater risk of AEs, independent of eGFR and albuminuria.

Kidney tubule health, mineral metabolism and adverse events in persons with CKD in SPRINT

BACKGROUND

Measures of kidney tubule health are risk markers for acute kidney injury (AKI) in persons with chronic kidney disease (CKD) during hypertension treatment, but their associations with other adverse events (AEs) are unknown.

METHODS

Among 2377 Systolic Blood Pressure Intervention Trial (SPRINT) participants with CKD, we measured at baseline eight urine biomarkers of kidney tubule health and two serum biomarkers of mineral metabolism pathways that act on the kidney tubules. Cox proportional hazards models were used to evaluate biomarker associations with risk of a composite of pre-specified serious AEs (hypotension, syncope, electrolyte abnormalities, AKI, bradycardia and injurious falls) and outpatient AEs (hyperkalemia and hypokalemia).

RESULTS

At baseline, the mean age was 73 ± 9 years and mean estimated glomerular filtration rate (eGFR) was 46 ± 11 mL/min/1.73 m2. During a median follow-up of 3.8 years, 716 (30%) participants experienced the composite AE. Higher urine interleukin-18, kidney injury molecule-1, neutrophil gelatinase-associated lipocalin (NGAL) and monocyte chemoattractant protein-1 (MCP-1), lower urine uromodulin (UMOD) and higher serum fibroblast growth factor-23 were individually associated with higher risk of the composite AE outcome in multivariable-adjusted models including eGFR and albuminuria. When modeling biomarkers in combination, higher NGAL [hazard ratio (HR) = 1.08 per 2-fold higher biomarker level, 95% confidence interval (CI) 1.03-1.13], higher MCP-1 (HR = 1.11, 95% CI 1.03-1.19) and lower UMOD (HR = 0.91, 95% CI 0.85-0.97) were each associated with higher composite AE risk. Biomarker associations did not vary by intervention arm (P > 0.10 for all interactions).

CONCLUSIONS

Among persons with CKD, several kidney tubule biomarkers are associated with higher risk of AEs during hypertension treatment, independent of eGFR and albuminuria.

Associations of High-Sensitivity Troponin and Natriuretic Peptide Levels With Serious Adverse Events in SPRINT

Background

Assessing the risk of serious adverse events (SAEs) during hypertension treatment is important for understanding the benefit‐harm trade‐offs of lower blood pressure goals. It is unknown whether high‐sensitivity cardiac troponin T (hs‐cTnT) and N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP) provide information about SAEs.

Methods and Results

In SPRINT (Systolic Blood Pressure Intervention Trial), hs‐cTnT and NT‐proBNP were measured at baseline in 8828 (94.3%) and 8836 (94.4%) participants, respectively. Multivariable Cox proportional hazards models were used to evaluate hs‐cTnT and NT‐proBNP associations with a composite of SPRINT’s SAEs of interest: hypotension, syncope, bradycardia, acute kidney injury, electrolyte abnormalities, and injurious falls. Elevations in hs‐cTnT and NT‐proBNP were associated with increased composite SAE risk (hazard ratio [HR] per 2‐fold higher hs‐cTnT: 1.15; 95% CI, 1.06‒1.25; HR per 2‐fold higher NT‐proBNP: 1.09; 95% CI, 1.05‒1.14). Compared with both hs‐cTnT and NT‐proBNP in the lower tertiles, both biomarkers in the highest tertile was associated with increased composite SAE risk (HR, 1.56; 95% CI, 1.32‒1.84). Composite SAE risk was higher in the intensive‐treatment group than in the standard‐treatment group for participants with both biomarkers in the lower tertiles, but similar between treatment groups for participants with both biomarkers in the highest tertile (P for interaction=0.008).

Conclusions

Elevations in hs‐cTnT and NT‐proBNP individually and in combination are associated with higher composite SAE risk in SPRINT. The differential impact of blood pressure treatment on SAE risk across combined biomarker categories may have implications for identifying individuals with more favorable benefit‐harm profiles for intensive blood pressure lowering.

Associations of CKD risk factors and longitudinal changes in urine biomarkers of kidney tubules among women living with HIV

BACKGROUND

Novel 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.

METHODS

We 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.

RESULTS

Of 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).

CONCLUSIONS

CKD 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.

Kidney tubule health scores and their associations with incident CKD in women living with HIV

OBJECTIVES

Individual kidney tubule biomarkers are associated with chronic kidney disease (CKD) risk in people living with HIV (PLWH). Whether a combination of kidney biomarkers can be integrated into informative summary scores for PLWH is unknown.

METHODS

We measured eight urine biomarkers of kidney tubule health at two visits over a 3-year period in 647 women living with HIV in the Women's Interagency Health Study. We integrated biomarkers into factor scores using exploratory factor analysis. We evaluated associations between CKD risk factors and factor scores, and used generalized estimating equations to determine associations between factor scores and risk of incident CKD.

RESULTS

Factor analysis identified two unique factor scores: a tubule reabsorption score comprising alpha-1-microglobulin, beta-2-microglobulin and trefoil factor-3; and a tubule injury score comprising interleukin-18 and kidney injury molecule-1. We modelled the two factor scores in combination with urine epidermal growth factor (EGF) and urine albumin. Predominantly HIV-related CKD risk factors were independently associated with worsening tubule reabsorption scores and tubule injury scores. During a median follow-up of 7 years, 9.7% (63/647) developed CKD. In multivariable time-updated models that adjusted for other factor scores and biomarkers simultaneously, higher tubule reabsorption scores [risk ratio (RR) = 1.27, 95% confidence interval (CI): 1.01-1.59 per 1 SD higher time-updated score], higher tubule injury scores (RR = 1.36, 95% CI: 1.05-1.76), lower urine EGF (RR = 0.75, 95% CI: 0.64-0.87), and higher urine albumin (RR = 1.20, 95% CI: 1.02-1.40) were jointly associated with risk of incident CKD.

CONCLUSIONS

We identified two novel and distinct dimensions of kidney tubule health that appear to quantify informative metrics of CKD risk in PLWH.

Urine Biomarkers of Kidney Tubule Health and Incident CKD Stage 3 in Women Living With HIV: A Repeated Measures Study

Rationale & Objective

Single 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 Design

Cohort study.

Setting & Participants

647 women living with HIV infection enrolled in the Women’s Interagency Health Study.

Exposures

14 urinary biomarkers of kidney tubule health measured at 2 visits over a 3-year period.

Outcome

Incident CKD, defined as estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m² at two 6-month visits and an average eGFR decline ≥ 3% per year.

Analytical Approach

We used multivariable generalized estimating equations adjusting for CKD risk factors to evaluate baseline, time-updated, and change-over-time biomarker associations with incident CKD. We compared CKD discrimination between models with and without a parsimoniously selected set of biomarkers.

Results

During a median 7 years of follow-up, 9.7% (63/647) developed CKD. In multivariable-adjusted analyses, 3 of 14 baseline biomarkers associated with incident CKD. In contrast, 10 of 14 time-updated biomarkers and 9 of 14 biomarkers modeled as change over time associated with incident CKD. Urinary epidermal growth factor (EGF), α₁-microglobulin (A1M), and albumin were selected using penalized regression methods. In the time-updated model, lower urinary EGF (risk ratio [RR] per 2-fold higher time-updated biomarker levels, 0.69; 95% CI, 0.58-0.81), higher urinary A1M (RR, 1.47; 95% CI, 1.25-1.73), and higher urinary albumin excretion (RR, 1.21; 95% CI, 1.03-1.42) were jointly associated with increased risk for CKD. Compared with a base model (C statistic, 0.75), CKD discrimination improved after adding urinary EGF, A1M, and albumin values across baseline (C = 0.81), time-updated (C = 0.83), and change-over-time (C = 0.83) models (P < 0.01 for all).

Limitations

Observational design, incident CKD definition limited to eGFR.

Conclusions

Repeat urinary biomarker measurements for kidney tubule health have stronger associations with incident CKD compared with baseline measurements and moderately improve CKD discrimination in women living with HIV infection.

HIV preexposure prophylaxis with tenofovir disoproxil fumarate/emtricitabine and changes in kidney function and tubular health

OBJECTIVE

To evaluate the effects of HIV preexposure prophylaxis (PrEP) with tenofovir disoproxial fumurate (TDF)/emtricitabine (FTC) on kidney function and kidney tubular health.

DESIGN

The Iniciativa Profilaxis Pre-Exposicion open-label extension (iPrEx-OLE) study enrolled former PrEP trial participants to receive open-label TDF/FTC. This study included 123 iPrEx-OLE participants who demonstrated PrEP adherence.

METHODS

We compared estimated glomerular filtration rate calculated using serum creatinine (eGFRcr), serum cystatin C (eGFRcys), and in combination (eGFRcr-cys), and a panel of 14 urine biomarkers reflecting kidney tubular health before and 6 months after PrEP initiation.

RESULTS

At baseline, mean eGFRcr, eGFRcys, and eGFRcr-cys were 108.3, 107.0, and 111.1 ml/min per 1.73 m, respectively. Six months after PrEP initiation, eGFRcr declined by -4% (95% CI: -5.7 to -2.4%), eGFRcys declined by -3.3% (95% CI: -8.3 to 1.9%), and eGFRcr-cys declined by -4.1% (95% CI: -7.5 to -0.7%). From the urine biomarker panel, α1-microglobulin and β2-microglobulin increased by 22.7% (95% CI: 11.8--34.7%) and 14.1% (95% CI: -6.1 to 38.6%), whereas chitinase-3-like 1 protein and monocyte chemoattractant protein-1 decreased by -37.7% (95% CI: -53.0 to -17.3%) and -15.6% (95% CI: -31.6 to 4.2%), respectively. Ten of the 14 urine biomarkers, including albumin, had estimated changes of less than 12% with wide confidence intervals.

CONCLUSION

Six months of PrEP with TDF/FTC was associated with decreases in eGFRcr and eGFRcys. We also observed for the first time changes in flour of 14 urine biomarkers reflecting kidney tubular health. These findings demonstrate that PrEP has direct effects on eGFR and the proximal tubule.

Associations of Urine Biomarkers with Kidney Function Decline in HIV-Infected and Uninfected Men

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.

Kidney disease risk factors associate with urine biomarkers concentrations in HIV-positive persons; a cross-sectional study

Background

HIV-positive persons bear an excess burden of chronic kidney disease (CKD); however, conventional methods to assess kidney health are insensitive and non-specific for detecting early kidney injury. Urinary biomarkers can detect early kidney injury, and may help mitigate the risk of overt CKD.

Methods

Cross-sectional study of HIV-positive persons in the Multicenter AIDS Cohort Study and the Women’s Interagency HIV Study. We measured levels of 14 biomarkers, capturing multiple dimensions of kidney injury. We then evaluated associations of known CKD risk factors with urine biomarkers using separate multivariable adjusted models for each biomarker.

Results

Of the 198 participants, one third were on HAART and virally suppressed. The vast majority (95%) had preserved kidney function as assessed by serum creatinine, with a median eGFR of 103 ml/min/1.73 m² (interquartile range (IQR): 88, 116). In our multivariable analyses, the associations of each CKD risk factor with urinary biomarker levels varied in magnitude. For example, HIV viral load was predominantly associated with elevations in interleukin(IL)-18, and albuminuria, while higher CD4 levels were associated with lower monocyte chemoattractant protein-1 (MCP-1) and β2-microglobulin. In contrast, older age was significantly associated with elevations in α1-microglobulin, kidney injury marker-1, clusterin, MCP-1, and chitinase-3-like protein-1 levels, as well as lower epidermal growth factor, and uromodulin levels.

Conclusions

Among HIV-positive persons, CKD risk factors are associated with unique and heterogeneous patterns of changes in urine biomarkers levels. Additional work is needed to develop parsimonious algorithms that integrate multiple biomarkers and clinical data to discern the risk of overt CKD and its progression.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-1192-y) contains supplementary material, which is available to authorized users.

Association of Urinary Biomarkers of Kidney Injury with Estimated GFR Decline in HIV-Infected Individuals following Tenofovir Disoproxil Fumarate Initiation

BACKGROUND AND OBJECTIVES

Tenofovir disoproxil fumarate (tenofovir) is associated with elevated concentrations of biomarkers of kidney damage and dysfunction in individuals with HIV. The relationship of these kidney biomarkers with longitudinal kidney function decline is unknown.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We evaluated associations of 14 urinary biomarkers of kidney injury with changes in eGFR among 198 men and women with HIV who initiated tenofovir between 2009 and 2015 in the Multicenter AIDS Cohort Study and Women's Interagency HIV Study. Urinary biomarkers included albumin-to-creatinine ratio, α-1-microglobulin, β-2-microglobulin, cystatin C, kidney injury molecule-1 (KIM-1), IL-18, neutrophil gelatinase-associated lipocalin (NGAL), clusterin, osteopontin, uromodulin, monocyte chemoattractant protein-1, EGF, trefoil factor 3, and chitinase 3-like protein 1. We used multivariable linear mixed-effect models controlling for demographics, traditional kidney disease risk factors, and HIV-related risk factors to evaluate associations of baseline biomarkers with first-year changes in eGFR, and associations of year 1 and first-year change in biomarkers with changes in eGFR from year 1 to year 3. We used the least absolute shrinkage and selection operator method to identify a parsimonious set of biomarkers jointly associated with changes in eGFR.

RESULTS

Median eGFR before tenofovir initiation was 103 (interquartile range, 88-116) ml/min per 1.73 m2. During the first year of tenofovir use, eGFR decreased on average by 9.2 (95% confidence interval, 6.5 to 11.9) ml/min per 1.73 m2 and was stable afterward (decrease of 0.62; 95% confidence interval, -0.85 to 2.1 ml/min per 1.73 m2 per year). After multivariable adjustment, higher baseline β-2-microglobulin, KIM-1, and clusterin were associated with larger first-year eGFR declines, whereas higher baseline uromodulin was associated with a smaller eGFR decline. First-year increase in urinary cystatin C and higher year 1 IL-18 were associated with larger annual eGFR declines from year 1 to year 3. The parsimonious models identified higher pre-tenofovir clusterin and KIM-1, lower pre-tenofovir uromodulin, and higher year 1 IL-18 as jointly associated with larger eGFR declines.

CONCLUSIONS

Urinary biomarkers of kidney injury measured before and after tenofovir initiation are associated with subsequent changes in eGFR in individuals with HIV.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2018_08_28_CJASNPodcast_18_9_S.mp3.

Association of Kidney Function and Early Kidney Injury With Incident Hypertension in HIV-Infected Women

Subclinical kidney disease is associated with developing hypertension in the general population, but data are lacking among HIV-infected people. We examined associations of kidney function and injury with incident hypertension in 823 HIV-infected and 267 HIV-uninfected women in the Women's Interagency HIV Study, a multicenter, prospective cohort of HIV-infected and uninfected women in the United States. Baseline kidney biomarkers included estimated glomerular filtration rate using cystatin C, urine albumin-to-creatinine ratio, and 7 urine biomarkers of tubular injury: α-1-microglobulin, interleukin-18, kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, liver fatty acid-binding protein, N-acetyl-β-d-glucosaminidase, and α1-acid-glycoprotein. We used multivariable Poisson regression to evaluate associations of kidney biomarkers with incident hypertension, defined as 2 consecutive visits of antihypertensive medication use. During a median follow-up of 9.6 years, 288 HIV-infected women (35%) developed hypertension. Among the HIV-infected women, higher urine albumin-to-creatinine ratio was independently associated with incident hypertension (relative risk =1.13 per urine albumin-to-creatinine ratio doubling, 95% confidence interval, 1.07-1.20), as was lower estimated glomerular filtration rate (relative risk =1.10 per 10 mL/min/1.73 m² lower estimated glomerular filtration rate; 95% confidence interval, 1.04-1.17). No tubular injury and dysfunction biomarkers were independently associated with incident hypertension in HIV-infected women. In contrast, among the HIV-uninfected women, urine albumin-to-creatinine ratio was not associated with incident hypertension, whereas higher urine interleukin-18, α1-acid-glycoprotein, and N-acetyl-β-d-glucosaminidase levels were significantly associated with incident hypertension. These findings suggest that early glomerular injury and kidney dysfunction may be involved in the pathogenesis of hypertension in HIV-infected people. The associations of tubular markers with hypertension in HIV-uninfected women should be validated in other studies.

Survey of clinical infant lung function testing practices

BACKGROUND

Data supporting the clinical use of infant lung function (ILF) tests are limited making the interpretation of clinical ILF measures difficult.

OBJECTIVES

To evaluate current ILF testing practices and to survey users regarding the indications, limitations and perceived clinical benefits of ILF testing.

METHODS

We created a 26-item survey hosted on the European Respiratory Society (ERS) website between January and May 2010. Notifications were sent to members of the ERS, American Thoracic Society and the Asian Pacific Society of Respirology. Responses were sought from ILF laboratory directors and pediatric respirologists. The survey assessed the clinical indications, patient populations, equipment and reference data used, and perceived limitations of ILF testing.

RESULTS

We received 148 responses with 98 respondents having ILF equipment and performing testing in a clinical capacity. Centers in North America were less likely to perform ≥50 studies/year than centers in Europe or other continents (13% vs. 41%). Most respondents used ILF data to either "start a new therapy" (78%) or "help decide about initiation of further diagnostic workup such as bronchoscopy, chest CT or serological testing" (69%). Factors reported as limiting clinical ILF testing were need for sedation, uncertainty regarding clinical impact of study results and time intensive nature of the study.

CONCLUSIONS

Clinical practices associated with ILF testing vary significantly; centers that perform more studies are more likely to use the results for clinical purposes and decision making. The future of ILF testing is uncertain in the face of the limitations perceived by the survey respondents.

Spectral-domain optical coherence tomographic assessment of severity of cystoid macular edema in retinopathy of prematurity

OBJECTIVE

To investigate whether the severity of cystoid macular edema (CME) in neonates who were 31 to 36 weeks' postmenstrual age, as viewed by spectral-domain optical coherence tomography (SD-OCT)imaging, predicts the severity of retinopathy of prematurity(ROP) or is related to systemic health.

DESIGN

Of 62 prematurely born neonates in a prospective institutional review board-approved study, 42 met the following inclusion criteria: at least 1 SD-OCT imaging session prior to 37 weeks' postmenstrual age and prior to ROP laser treatment, if a laser treatment was performed,and an ophthalmic ROP examination at or after 41 weeks' postmenstrual age, evidence of complete retinal vascularization in zone III, or documentation through telephone report of such information after transfer of care.Measures of CME severity, including central foveal thickness,retinal layer thicknesses, and foveal-to-parafoveal thickness ratio in 1 eye per subject, were compared with ROP outcomes: laser treatment, maximum plus disease,and maximum ROP stage. Systemic health factors were also correlated.

RESULTS

Cystoid macular edema was present in 50% of neonates. Multiple elongated cystoid structures within the inner nuclear layer were most common. The presence of CME was not associated with ROP outcomes. The central foveal thickness, the thickness of the inner retinal layers, and the foveal-to-parafoveal thickness ratio were higher in eyes that required laser treatment or that developed plus disease or ROP stage 3. Cystoid macular edema was not clearly associated with systemic factors.

CONCLUSIONS

Cystoid macular edema is common in premature infants screened for ROP before 37 weeks' postmenstrual age, with the most common SD-OCT phenotype ofa bulging fovea from multiple elongated cystoid spaces. Detection of CME is not associated with ROP severity; however,tomographic thickness measurements could potentially predict a higher risk of requiring laser treatment or developing plus disease or ROP stage 3. Systemic health factors are probably not related to the development of CME.

Sepsis in young infants with congenital heart disease

BACKGROUND

We sought to describe the incidence, pathogen distribution, and mortality associated with blood culture-proven sepsis in young infants with congenital heart disease (CHD) admitted to a neonatal intensive care unit (NICU).

METHODS

Cohort study of all blood cultures obtained from infants with CHD between 4 and 120 days of age cared for in 250 NICUs managed by the Pediatrix Medical Group in the United States between 1996 and 2007.

RESULTS

Of 11,638 infants with CHD, 656 (6%) had 821 episodes of sepsis: a cumulative incidence of 71/1000 admissions. Gram-positive organisms were the most common cause (64%), and coagulase-negative Staphylococcus and Staphylococcus aureus were the most frequently isolated species. On multivariable regression, infants with sepsis were more likely to die compared to infants with sterile blood cultures (odds ratio [OR] = 1.53 [95% confidence interval: 1.09, 2.13]). Infants with Gram-negative bacteraemia and candidaemia were more likely to die than infants with sterile blood cultures (OR = 2.01 [1.20, 3.37], and OR = 3.18 [1.60, 6.34], respectively).

CONCLUSION

Infants with CHD have a high incidence of culture-proven sepsis, especially with staphylococcal organisms. Gram-negative bacteraemia and candidaemia are strongly associated with increased mortality in this group of young infants.