Proton Pump Inhibitor Use, Fatigue, and Health-Related Quality of Life in Kidney Transplant Recipients:Results From the TransplantLines Biobank and Cohort Study

RATIONALE &amp; OBJECTIVE: Prior studies report that the use of proton-pump inhibitors (PPIs) can adversely affect gut microbiota and gastrointestinal uptake of micronutrients, in particular iron and magnesium, and are used frequently by kidney transplant recipients (KTR). Altered gut microbiota, iron deficiency, and magnesium deficiency have been implicated in the pathogenesis of chronic fatigue. Therefore, we hypothesized that PPI use may be an important and underappreciated cause of fatigue and reduced health-related quality of life (HRQoL) in this population.STUDY DESIGN: Cross-sectional study.SETTING &amp; PARTICIPANTS: KTR (≥1 year after transplantation) enrolled in the TransplantLines Biobank and Cohort Study.EXPOSURE: PPI use, PPI type, PPI dosage, and duration of PPI use.OUTCOMES: Fatigue and HRQoL, assessed using the validated Checklist Individual Strength 20 Revised questionnaire and Short Form-36 questionnaire.ANALYTICAL APPROACH: Logistic and linear regression.RESULTS: We included 937 KTR (mean age 56±13 years, 39% female) at a median of 3 [1-10] years after transplantation. PPI use was associated with fatigue severity (regression coefficient 4.02, 95%CI 2.18 to 5.85, p&lt;0.001), a higher risk of severe fatigue (OR 2.05, 95%CI 1.48 to 2.84, p&lt;0.001), lower physical HRQoL (regression coefficient -8.54, 95%CI -11.54 to -5.54, p&lt;0.001), and lower mental HRQoL (regression coefficient -4.66, 95%CI -7.15 to -2.17, p&lt;0.001). These associations were independent of potential confounders including age, time since transplantation, history of upper gastrointestinal disease, antiplatelet therapy, and the total number of medications. They were present among all individually assessed PPI types and were dose-dependent. Duration of PPI exposure was only associated with fatigue severity.LIMITATIONS: Residual confounding and inability to assess causal relationships CONCLUSIONS: PPI use is independently associated with fatigue and lower HRQoL among KTR. PPI use might be an easily accessible target for alleviating fatigue and improving HRQoL among KTR. Further studies examining the effect of PPI exposure in this population are warranted.</p

Learning Interpretable Rules for Multi-label Classification

Multi-label classification (MLC) is a supervised learning problem in which, contrary to standard multiclass classification, an instance can be associated with several class labels simultaneously. In this chapter, we advocate a rule-based approach to multi-label classification. Rule learning algorithms are often employed when one is not only interested in accurate predictions, but also requires an interpretable theory that can be understood, analyzed, and qualitatively evaluated by domain experts. Ideally, by revealing patterns and regularities contained in the data, a rule-based theory yields new insights in the application domain. Recently, several authors have started to investigate how rule-based models can be used for modeling multi-label data. Discussing this task in detail, we highlight some of the problems that make rule learning considerably more challenging for MLC than for conventional classification. While mainly focusing on our own previous work, we also provide a short overview of related work in this area.Comment: Preprint version. To appear in: Explainable and Interpretable Models in Computer Vision and Machine Learning. The Springer Series on Challenges in Machine Learning. Springer (2018). See http://www.ke.tu-darmstadt.de/bibtex/publications/show/3077 for further informatio

Plasma Lead Concentration and Risk of Late Kidney Allograft Failure:Findings From the TransplantLines Biobank and Cohort Studies

RATIONALE & OBJECTIVE: Heavy metals are known to induce kidney damage and recent studies have linked minor exposures to cadmium and arsenic with increased risk of kidney allograft failure, yet the potential association of lead (Pb) with late graft failure in kidney transplant recipients (KTR) remains unknown. STUDY DESIGN: Prospective cohort study in the Netherlands. SETTING & PARTICIPANTS: We studied outpatient KTR (n=670) with a functioning graft for ≥1 year recruited at a university setting (2008-2011, NCT02811835) and followed, on average, for 4.9 (IQR, 3.4‒5.5) years. Additionally, end-stage kidney disease patients (n=46) enrolled in the ongoing TransplantLines Cohort and Biobank Study (2016-2017, NCT03272841) were studied at admission for transplantation and at 3, 6, 12, and 24 months after transplantation. EXPOSURE: Plasma Pb was log2 transformed to estimate the association with outcomes per doubling of plasma Pb concentration and also considered categorically as tertiles of the Pb distribution. OUTCOME: Kidney graft failure (restart of dialysis or re-transplantation) with the competing event of death with a functioning graft. ANALYTICAL APPROACH: Multivariable-adjusted cause-specific hazards models where follow-up of KTR who died with a functioning graft was censored. RESULTS: Median baseline plasma Pb was 0.31 (IQR, 0.22─0.45) μg/L among all KTRs. During follow-up, 78 (12%) KTR developed graft failure. Higher plasma Pb was associated with increased risk of graft failure (HR 1.59, 95% CI 1.14‒2.21 per doubling; P=0.006) independent of age, sex, transplant characteristics, eGFR, proteinuria, smoking status, alcohol intake, and plasma concentrations of cadmium and arsenic. These findings remained materially unchanged after additional adjustment for dietary intake and were consistent with those of analyses examining Pb categorically. In serial measurements, plasma Pb was significantly higher at admission for transplantation than at 3-months post-transplant (P=0.001), after which it remained stable over 2 years of follow-up (P=0.2). LIMITATIONS: Observational study design. CONCLUSIONS: Pretransplant plasma Pb concentrations, which fall after transplantation, are associated with increased risk of late kidney allograft failure. These findings warrant further studies to evaluate whether preventive or therapeutic interventions to decrease plasma Pb may represent novel risk-management strategies to decrease the rate of kidney allograft failure

Plasma Lead Concentration and Risk of Late Kidney Allograft Failure:Findings From the TransplantLines Biobank and Cohort Studies

Rationale &amp; Objective: Heavy metals are known to induce kidney damage, and recent studies have linked minor exposures to cadmium and arsenic with increased risk of kidney allograft failure, yet the potential association of lead with late graft failure in kidney transplant recipients (KTRs) remains unknown. Study Design: Prospective cohort study in The Netherlands. Setting &amp; Participants: We studied outpatient KTRs (n = 670) with a functioning graft for ≥1 year recruited at a university setting (2008-2011) and followed for a median of 4.9 (interquartile range, 3.4-5.5) years. Additionally, patients with chronic kidney disease (n = 46) enrolled in the ongoing TransplantLines Cohort and Biobank Study (2016-2017, ClinicalTrials.gov identifier NCT03272841) were studied at admission for transplant and at 3, 6, 12, and 24 months after transplant. Exposure: Plasma lead concentration was log2-transformed to estimate the association with outcomes per doubling of plasma lead concentration and also considered categorically as tertiles of lead distribution. Outcome: Kidney graft failure (restart of dialysis or repeat transplant) with the competing event of death with a functioning graft. Analytical Approach: Multivariable-adjusted cause-specific hazards models in which follow-up of KTRs who died with a functioning graft was censored. Results: Median baseline plasma lead concentration was 0.31 (interquartile range, 0.22-0.45) μg/L among all KTRs. During follow-up, 78 (12%) KTRs experienced graft failure. Higher plasma lead concentration was associated with increased risk of graft failure (hazard ratio, 1.59 [95% CI, 1.14-2.21] per doubling; P = 0.006) independent of age, sex, transplant characteristics, estimated glomerular filtration rate, proteinuria, smoking status, alcohol intake, and plasma concentrations of cadmium and arsenic. These findings remained materially unchanged after additional adjustment for dietary intake and were consistent with those of analyses examining lead categorically. In serial measurements, plasma lead concentration was significantly higher at admission for transplant than at 3 months after transplant (P = 0.001), after which it remained stable over 2 years of follow-up (P = 0.2). Limitations: Observational study design. Conclusions: Pretransplant plasma lead concentrations, which decrease after transplant, are associated with increased risk of late kidney allograft failure. These findings warrant further studies to evaluate whether preventive or therapeutic interventions to decrease plasma lead concentration may represent novel risk-management strategies to decrease the rate of kidney allograft failure.</p

Plasma Lead Concentration and Risk of Late Kidney Allograft Failure:Findings From the TransplantLines Biobank and Cohort Studies

Rationale &amp; Objective: Heavy metals are known to induce kidney damage, and recent studies have linked minor exposures to cadmium and arsenic with increased risk of kidney allograft failure, yet the potential association of lead with late graft failure in kidney transplant recipients (KTRs) remains unknown. Study Design: Prospective cohort study in The Netherlands. Setting &amp; Participants: We studied outpatient KTRs (n = 670) with a functioning graft for ≥1 year recruited at a university setting (2008-2011) and followed for a median of 4.9 (interquartile range, 3.4-5.5) years. Additionally, patients with chronic kidney disease (n = 46) enrolled in the ongoing TransplantLines Cohort and Biobank Study (2016-2017, ClinicalTrials.gov identifier NCT03272841) were studied at admission for transplant and at 3, 6, 12, and 24 months after transplant. Exposure: Plasma lead concentration was log2-transformed to estimate the association with outcomes per doubling of plasma lead concentration and also considered categorically as tertiles of lead distribution. Outcome: Kidney graft failure (restart of dialysis or repeat transplant) with the competing event of death with a functioning graft. Analytical Approach: Multivariable-adjusted cause-specific hazards models in which follow-up of KTRs who died with a functioning graft was censored. Results: Median baseline plasma lead concentration was 0.31 (interquartile range, 0.22-0.45) μg/L among all KTRs. During follow-up, 78 (12%) KTRs experienced graft failure. Higher plasma lead concentration was associated with increased risk of graft failure (hazard ratio, 1.59 [95% CI, 1.14-2.21] per doubling; P = 0.006) independent of age, sex, transplant characteristics, estimated glomerular filtration rate, proteinuria, smoking status, alcohol intake, and plasma concentrations of cadmium and arsenic. These findings remained materially unchanged after additional adjustment for dietary intake and were consistent with those of analyses examining lead categorically. In serial measurements, plasma lead concentration was significantly higher at admission for transplant than at 3 months after transplant (P = 0.001), after which it remained stable over 2 years of follow-up (P = 0.2). Limitations: Observational study design. Conclusions: Pretransplant plasma lead concentrations, which decrease after transplant, are associated with increased risk of late kidney allograft failure. These findings warrant further studies to evaluate whether preventive or therapeutic interventions to decrease plasma lead concentration may represent novel risk-management strategies to decrease the rate of kidney allograft failure.</p

Boron Intake and decreased risk of mortality in kidney transplant recipients

Purpose: In a search for potentially modifiable factors to improve long-term outcome among kidney transplant recipients (KTR), we hypothesized that boron exposure is associated with improved long-term outcome in KTR. Methods: We determined 24 h urinary boron excretion using inductively coupled plasma mass spectrometry as a measure of boron exposure in 693 stable KTR (57% male, mean age 53y), enrolled in the TransplantLines Food and Nutrition Biobank and Cohort Study. Dietary intake was assessed using validated food-frequency questionnaires. Results: Linear regression analyses showed that dietary intake of fruit, wine and nuts were key determinants of boron excretion. In addition, boron excretion was negatively correlated with homocysteine and inflammatory parameters. In total, 73 (32%), 47 (20%) and 30 (13%) KTR died among the lowest, middle and highest tertiles of 24 h urinary boron excretion, respectively (Plog-rank &lt; 0.001). Cox regression analyses showed that high boron excretion was strongly associated with lower risk of mortality, independent of age, sex, estimated glomerular filtration rate and history of cardiovascular disease (HR per doubling: 0.51, 95% CI: 0.40 to 0.66, P &lt; 0.001). Conclusion: Boron may be an overlooked target to improve long-term survival among KTR and potentially other patients, likely through pathways other than inflammation or the methionine-homocysteine cycle that were previously suggested. Interventional trials are warranted to confirm the potential of dietary boron supplementation in KTR and other patient populations.</p

Airflow Limitation, Fatigue, and Health-Related Quality of Life in Kidney Transplant Recipients

BACKGROUND AND OBJECTIVES: Many kidney transplant recipients suffer from fatigue and poor health-related quality of life. Airflow limitation may be an underappreciated comorbidity among kidney transplant recipients, which could contribute to fatigue and lower health-related quality of life in this population. In this study, we compared the prevalence of airflow limitation between kidney transplant recipients and healthy controls and investigated associations of airflow limitation with fatigue and health-related quality of life in kidney transplant recipients. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Data from the ongoing TransplantLines Biobank and Cohort study were used. Airflow limitation was defined as forced exhaled volume in 1 second less than the fifth percentile of the general population. Fatigue and health-related quality of life were assessed using checklist individual strength 20 revised (CIS20-R) and Short Form-36 (SF-36) questionnaires. RESULTS: A total of 539 kidney transplant recipients (58% men; mean age 56±13 years) and 244 healthy controls (45% men; mean age 57±10 years) were included. Prevalence of airflow limitation was higher in kidney transplant recipients than in healthy controls (133 [25%] versus 25 [10%]). In multinomial regression models, airflow limitation was independently associated with fatigue severity (odds ratio moderate fatigue, 1.68; 95% confidence interval, 0.92 to 3.09 and odds ratio severe fatigue, 2.51; 95% confidence interval, 1.39 to 4.55; P=0.007) and lower physical health-related quality of life (-0.11 SDs; 95% confidence interval, -0.19 to -0.02; P=0.01) in kidney transplant recipients. In exploratory mediation analyses, fatigue accounted for 79% of the association of airflow limitation with physical health-related quality of life. CONCLUSIONS: Airflow limitation is common among kidney transplant recipients. Its occurrence is associated with more than two times higher risk of severe fatigue, and it is associated with lower physical health-related quality of life. Mediation analyses suggest that airflow limitation causes fatigue, which in turn, decreases physical health-related quality of life. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER: TransplantLines: The Transplantation Biobank, NCT03272841 PODCAST: This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2021_11_08_CJN06600521.mp3

Boron Intake and decreased risk of mortality in kidney transplant recipients

Purpose: In a search for potentially modifiable factors to improve long-term outcome among kidney transplant recipients (KTR), we hypothesized that boron exposure is associated with improved long-term outcome in KTR. Methods: We determined 24 h urinary boron excretion using inductively coupled plasma mass spectrometry as a measure of boron exposure in 693 stable KTR (57% male, mean age 53y), enrolled in the TransplantLines Food and Nutrition Biobank and Cohort Study. Dietary intake was assessed using validated food-frequency questionnaires. Results: Linear regression analyses showed that dietary intake of fruit, wine and nuts were key determinants of boron excretion. In addition, boron excretion was negatively correlated with homocysteine and inflammatory parameters. In total, 73 (32%), 47 (20%) and 30 (13%) KTR died among the lowest, middle and highest tertiles of 24 h urinary boron excretion, respectively (Plog-rank &lt; 0.001). Cox regression analyses showed that high boron excretion was strongly associated with lower risk of mortality, independent of age, sex, estimated glomerular filtration rate and history of cardiovascular disease (HR per doubling: 0.51, 95% CI: 0.40 to 0.66, P &lt; 0.001). Conclusion: Boron may be an overlooked target to improve long-term survival among KTR and potentially other patients, likely through pathways other than inflammation or the methionine-homocysteine cycle that were previously suggested. Interventional trials are warranted to confirm the potential of dietary boron supplementation in KTR and other patient populations.</p

Altered Gut Microbial Fermentation and Colonization with Methanobrevibacter smithii in Renal Transplant Recipients

Renal transplant recipients (RTRs) often suffer from posttransplant diarrhea. The observed dysbiosis in RTR may influence the fermentation processes in the gut. In this study, we aimed to investigate whether fermentation differs between RTRs and healthy controls (HCs), by measuring breath H2 and CH4 concentrations. Additionally, we determined the fecal presence of the methanogen Methanobrevibacter smithii (M. smithii), which plays a main role in the process of methanogenesis. Data from the TransplantLines Biobank and Cohort Study (NCT03272841) was used. A total of 142 RTRs and 77 HCs were included. Breath H2 concentrations in RTRs were not significantly different from HCs. Breath CH4 concentrations in RTRs were significantly lower compared with HCs (median [interquartile range (IQR)] 7.5 [3.9–10.6] ppm vs. 16.0 [8.0–45.5] ppm, p < 0.001). M. smithii was less frequently present in the feces of RTRs compared to HCs (28.6% vs. 86.4% resp., p < 0.001). Our findings regarding the altered methanogenesis in the gut of RTRs show similarities with previous results in inflammatory bowel disease patients. These findings provide novel insight into the alterations of fermentation after renal transplantation, which may contribute to understanding the occurrence of posttransplant diarrhea. View Full-Tex

Boron Intake and decreased risk of mortality in kidney transplant recipients

PURPOSE: In a search for potentially modifiable factors to improve long-term outcome among kidney transplant recipients (KTR), we hypothesized that boron exposure is associated with improved long-term outcome in KTR. METHODS: We determined 24 h urinary boron excretion using inductively coupled plasma mass spectrometry as a measure of boron exposure in 693 stable KTR (57% male, mean age 53y), enrolled in the TransplantLines Food and Nutrition Biobank and Cohort Study. Dietary intake was assessed using validated food-frequency questionnaires. RESULTS: Linear regression analyses showed that dietary intake of fruit, wine and nuts were key determinants of boron excretion. In addition, boron excretion was negatively correlated with homocysteine and inflammatory parameters. In total, 73 (32%), 47 (20%) and 30 (13%) KTR died among the lowest, middle and highest tertiles of 24 h urinary boron excretion, respectively (P(log-rank) < 0.001). Cox regression analyses showed that high boron excretion was strongly associated with lower risk of mortality, independent of age, sex, estimated glomerular filtration rate and history of cardiovascular disease (HR per doubling: 0.51, 95% CI: 0.40 to 0.66, P < 0.001). CONCLUSION: Boron may be an overlooked target to improve long-term survival among KTR and potentially other patients, likely through pathways other than inflammation or the methionine-homocysteine cycle that were previously suggested. Interventional trials are warranted to confirm the potential of dietary boron supplementation in KTR and other patient populations. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00394-021-02702-0