Dataset Information

Tubular Biomarkers and Chronic Kidney Disease Progression in SPRINT Participants.

ABSTRACT:

Background

Kidney tubular atrophy on biopsy is a strong predictor of chronic kidney disease (CKD) progression, but tubular health is poorly quantified by traditional measures including estimated glomerular filtration rate (eGFR) and albuminuria. We hypothesized that urinary biomarkers of impaired tubule function would be associated with faster eGFR declines in persons with CKD.

Methods

We measured baseline urine concentrations of uromodulin, β2-microglobulin (β2m), and α1-microglobulin (α1m) among 2,428 participants of the Systolic Blood Pressure Intervention Trial with an eGFR <60 mL/min/1.73 m2. We used linear mixed models to evaluate biomarker associations with annualized relative change in eGFR, stratified by randomization arm.

Results

At baseline, the mean age was 73 ± 9 years and eGFR was 46 ± 11 mL/min/1.73 m2. In the standard blood pressure treatment arm, each 2-fold higher urinary uromodulin was associated with slower % annual eGFR decline (0.34 [95% CI: 0.08, 0.60]), whereas higher urinary β2m was associated with faster % annual eGFR decline (-0.10 [95% CI: -0.18, -0.02]) in multivariable-adjusted models including baseline eGFR and albuminuria. Associations were weaker and did not reach statistical significance in the intensive blood pressure treatment arm for either uromodulin (0.11 [-0.13, 0.35], p value for interaction by treatment arm = 0.045) or β2m (-0.01 [-0.08, 0.08], p value for interaction = 0.001). Urinary α1m was not independently associated with eGFR decline in the standard (0.01 [-0.22, 0.23]) or intensive (0.03 [-0.20, 0.25]) arm.

Conclusions

Among trial participants with hypertension and CKD, baseline measures of tubular function were associated with subsequent declines in kidney function, although these associations were diminished by intensive blood pressure control.

SUBMITTER: Jotwani V

PROVIDER: S-EPMC7606644 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Rationale & objectiveThe Systolic Blood Pressure Intervention Trial (SPRINT) compared the effect of intensive versus standard systolic blood pressure targets on cardiovascular morbidity and mortality. In this ancillary study, we evaluated the use of exploratory factor analysis (EFA) to combine biomarkers of kidney tubule health in urine and plasma and then study their role in longitudinal estimated glomerular filtration rate (eGFR) change and risk of acute kidney injury (AKI).Study designObservational cohort nested in a clinical trial.Setting & participants2,351 SPRINT participants with eGFR < 60 mL/min/1.73 m2 at baseline.ExposureLevels of neutrophil gelatinase-associated lipocalin (NGAL), interleukin 18 (IL-18), chitinase-3-like protein (YKL-40), kidney injury molecule 1 (KIM-1), monocyte chemoattractant protein 1 (MCP-1), α1-microglobulin (A1M) and β2-microglobulin (B2M), uromodulin (UMOD), fibroblast growth factor 23 (FGF-23), and intact parathyroid hormone (PTH).OutcomeLongitudinal changes in eGFR and risk of AKI.Analytical approachWe performed EFA to capture different tubule pathophysiologic processes. We used linear mixed effects models to evaluate the association of each factor with longitudinal changes in eGFR. We evaluated the association of the tubular factors scores with AKI using Cox proportional hazards regression.ResultsFrom 10 biomarkers, EFA generated 4 factors reflecting tubule injury/repair (NGAL, IL-18, and YKL-40), tubule injury/fibrosis (KIM-1 and MCP-1), tubule reabsorption (A1M and B2M), and tubule reserve/mineral metabolism (UMOD, FGF-23, and PTH). Each 1-SD higher tubule reserve/mineral metabolism factor score was associated with a 0.58% (95% CI, 0.39%-0.67%) faster eGFR decline independent of baseline eGFR and albuminuria. Both the tubule injury/repair and tubule injury/fibrosis factors were independently associated with future risk of AKI (per 1 SD higher, HRs of 1.18 [95% CI, 1.10-1.37] and 1.23 [95% CI, 1.02-1.48], respectively).LimitationsThe factors require validation in other settings.ConclusionsEFA allows parsimonious subgrouping of biomarkers into factors that are differentially associated with progressive eGFR decline and AKI. These subgroups may provide insights into the pathological processes driving adverse kidney outcomes.

Project description:Background and objectivesThe Systolic Blood Pressure Intervention Trial (SPRINT) demonstrated that intensive BP lowering reduced the risk of cardiovascular disease, but increased eGFR decline. Serum parathyroid hormone (PTH) and fibroblast growth factor-23 (FGF23) concentrations are elevated in CKD and are associated with cardiovascular disease. We evaluated whether intact PTH or intact FGF23 concentrations modify the effects of intensive BP control on cardiovascular events, heart failure, and all-cause mortality in SPRINT participants with CKD.Design, setting, participants, & measurementsWe measured PTH and FGF23 in 2486 SPRINT participants with eGFR<60 ml/min per 1.73 m2 at baseline. Cox models were used to evaluate whether serum PTH and FGF23 concentrations were associated with cardiovascular events, heart failure, and all-cause mortality, and whether PTH and FGF23 modified the effects of intensive BP control.ResultsThe mean age of this subcohort was 73 years, 60% were men, and mean eGFR was 46±11 ml/min per 1.73 m2. Median PTH was 48 (interquartile range [IQR], 35-67) pg/ml and FGF23 was 66 (IQR, 52-88) pg/ml. There were 261 composite cardiovascular events, 102 heart failure events, and 179 deaths within the subcohort. The adjusted hazard ratio (HR) per doubling of PTH concentration for cardiovascular events, heart failure, and all-cause mortality were 1.29 (95% confidence interval [95% CI], 1.06 to 1.57), 1.32 (95% CI, 0.96 to 1.83), and 1.04 (95% CI, 0.82 to 1.31), respectively. There were significant interactions between PTH and BP arm for both the cardiovascular (P-interaction=0.01) and heart failure (P-interaction=0.004) end points. Participants with a PTH above the median experienced attenuated benefits of intensive BP control on cardiovascular events (adjusted HR, 1.02; 95% CI, 0.72 to 1.42) compared with participants with a PTH below the median (adjusted HR, 0.67; 95% CI, 0.45 to 1.00). FGF23 was not independently associated with any outcome and did not modify the effects of the intervention.ConclusionsSPRINT participants with CKD and a high serum PTH received less cardiovascular protection from intensive BP therapy than participants with a lower serum PTH.