Statistical Methods for Cohort Studies of CKD: Survival Analysis in the Setting of Competing Risks

Associations of Urine and Plasma Metabolites with Kidney Failure and Death in a CKD Cohort

RATIONALE & OBJECTIVE

Biomarkers that enable better identification of persons with chronic kidney disease (CKD) who are at higher risk for disease progression and adverse events are needed. This study sought to identify urine and plasma metabolites associated with progression of kidney disease.

STUDY DESIGN

Prospective metabolome-wide association study.

SETTING & PARTICIPANTS

Persons with CKD enrolled in the German CKD Study (GCKD) with metabolite measurements; with external validation within the Atherosclerosis Risk in Communities Study.

EXPOSURES

1,513 urine and 1,416 plasma metabolites (Metabolon, Inc.) measured at study entry using untargeted mass spectrometry.

OUTCOMES

Main endpoints were kidney failure (KF), and a composite endpoint of KF, eGFR <15 mL/min/1.73m2, or 40% decline in eGFR (CKE). Death from any cause was a secondary endpoint. After a median of 6.5 years follow-up, 500 persons experienced KF, 1,083 experienced CKE and 680 died.

ANALYTICAL APPROACH

Time-to-event analyses using multivariable proportional hazard regression models in a discovery-replication design, with external validation.

RESULTS

5,088 GCKD participants were included in analyses of urine metabolites and 5,144 in analyses of plasma metabolites. Among 182 unique metabolites, 30 were significantly associated with KF, 49 with CKE, and 163 with death. The strongest association with KF was observed for plasma hydroxyasparagine (hazard ratio: 1.95, 95% confidence interval: 1.68-2.25). An unnamed metabolite measured in plasma and urine was significantly associated with KF, CKE, and death. External validation of the identified associations of metabolites with KF or CKE revealed direction-consistency for 88% of observed associations. Selected associations of 18 metabolites with study outcomes have not been previously reported.

LIMITATIONS

Use of observational data and semi-quantitative metabolite measurements at a single time point.

CONCLUSIONS

The observed associations between metabolites and KF, CKE or death in persons with CKD confirmed previously reported findings and also revealed several associations not previously described. These findings warrant confirmatory research in other study cohorts.

Differential associations of fetuin-A and calcification propensity with cardiovascular events and subsequent mortality in patients undergoing hemodialysis

Background

Fetuin-A inhibits precipitation of calcium-phosphate crystals by forming calciprotein particles (CPP). A novel T50 test, which measures transformation time from primary to secondary CPP, is an index for calcification propensity. Both lower fetuin-A and shorter T50 levels were associated with cardiovascular disease (CVD) risk in patients with chronic kidney disease (CKD). Extremely high risk for CVD death in advanced CKD patients consists of high-incidental CVD event and high mortality after CVD event. To date, it is unclear whether fetuin-A and/or T50 can equally predict each CVD outcome.

Methods

This prospective cohort study examined patients undergoing maintenance hemodialysis. The exposures were fetuin-A and T50. The outcomes of interests were new CVD events and subsequent deaths. The patients were categorized into tertiles of fetuin-A or T50 (T1 to T3).

Results

We identified 190 new CVD events during the 5-year follow-up of the 513 patients and 59 deaths subsequent to the CVD events during 2.5-year follow-up. A lower fetuin-A but not T50 was significantly associated with new CVD events [subdistribution hazard ratio (HR) 1.73, 95% confidence interval (CI) 1.15-2.61, P = .009 for T1 vs T3]. In contrast, a shorter T50 but not fetuin-A was a significant predictor of deaths after CVD events (HR 3.31, 95% CI 1.42-7.74, P = .006 for T1 + T2 vs T3). A lower fetuin-A was predictive of new CVD events, whereas a shorter T50 was more preferentially associated with subsequent death.

Conclusion

These results indicate that fetuin-A and T50 are involved in cardiovascular risk in different manners.

Prediction the prognosis of the poisoned patients undergoing hemodialysis using machine learning algorithms

BACKGROUND

Hemodialysis is a life-saving treatment used to eliminate toxins and metabolites from the body during poisoning. Despite its effectiveness, there needs to be more research on this method precisely, with most studies focusing on specific poisoning. This study aims to bridge the existing knowledge gap by developing a machine-learning prediction model for forecasting the prognosis of the poisoned patient undergoing hemodialysis.

METHODS

Using a registry database from 2016 to 2022, this study conducted a retrospective cohort study at Loghman Hakim Hospital. First, the relief feature selection algorithm was used to identify the most important variables influencing the prognosis of poisoned patients undergoing hemodialysis. Second, four machine learning algorithms, including extreme gradient boosting (XGBoost), histgradient boosting (HGB), k-nearest neighbors (KNN), and adaptive boosting (AdaBoost), were trained to construct predictive models for predicting the prognosis of poisoned patients undergoing hemodialysis. Finally, the performance of paired feature selection and machine learning (ML) algorithm were evaluated to select the best models using five evaluation metrics including accuracy, sensitivity, specificity the area under the curve (AUC), and f1-score.

RESULT

The study comprised 980 patients in total. The experimental results showed that ten variables had a significant influence on prognosis outcomes including age, intubation, acidity (PH), previous medical history, bicarbonate (HCO3), Glasgow coma scale (GCS), intensive care unit (ICU) admission, acute kidney injury, and potassium. Out of the four models evaluated, the HGB classifier stood out with superior results on the test dataset. It achieved an impressive mean classification accuracy of 94.8%, a mean specificity of 93.5 a mean sensitivity of 94%, a mean F-score of 89.2%, and a mean receiver operating characteristic (ROC) of 92%.

CONCLUSION

ML-based predictive models can predict the prognosis of poisoned patients undergoing hemodialysis with high performance. The developed ML models demonstrate valuable potential for providing frontline clinicians with data-driven, evidence-based tools to guide time-sensitive prognosis evaluations and care decisions for poisoned patients in need of hemodialysis. Further large-scale multi-center studies are warranted to validate the efficacy of these models across diverse populations.

Interpretable machine learning for predicting chronic kidney disease progression risk

Objective

Chronic kidney disease (CKD) poses a major global health burden. Early CKD risk prediction enables timely interventions, but conventional models have limited accuracy. Machine learning (ML) enhances prediction, but interpretability is needed to support clinical usage with both in diagnostic and decision-making.

Methods

A cohort of 491 patients with clinical data was collected for this study. The dataset was randomly split into an 80% training set and a 20% testing set. To achieve the first objective, we developed four ML algorithms (logistic regression, random forests, neural networks, and eXtreme Gradient Boosting (XGBoost)) to classify patients into two classes-those who progressed to CKD stages 3-5 during follow-up (positive class) and those who did not (negative class). For the classification task, the area under the receiver operating characteristic curve (AUC-ROC) was used to evaluate model performance in discriminating between the two classes. For survival analysis, Cox proportional hazards regression (COX) and random survival forests (RSFs) were employed to predict CKD progression, and the concordance index (C-index) and integrated Brier score were used for model evaluation. Furthermore, variable importance, partial dependence plots, and restrict cubic splines were used to interpret the models' results.

Results

XGBOOST demonstrated the best predictive performance for CKD progression in the classification task, with an AUC-ROC of 0.867 (95% confidence interval (CI): 0.728-0.100), outperforming the other ML algorithms. In survival analysis, RSF showed slightly better discrimination and calibration on the test set compared to COX, indicating better generalization to new data. Variable importance analysis identified estimated glomerular filtration rate, age, and creatinine as the most important predictors for CKD survival analysis. Further analysis revealed non-linear associations between age and CKD progression, suggesting higher risks in patients aged 52-55 and 65-66 years. The association between cholesterol levels and CKD progression was also non-linear, with lower risks observed when cholesterol levels were in the range of 5.8-6.4 mmol/L.

Conclusions

Our study demonstrated the effectiveness of interpretable ML models for predicting CKD progression. The comparison between COX and RSF highlighted the advantages of ML in survival analysis, particularly in handling non-linearity and high-dimensional data. By leveraging interpretable ML for unraveling risk factor relationships, contrasting predictive techniques, and exposing non-linear associations, this study significantly advances CKD risk prediction to enable enhanced clinical decision-making.

Association between inpatient education program for patients with pre-dialysis chronic kidney disease and new-onset cardiovascular disease after initiating dialysis

BACKGROUND

The association between inpatient education programs (IEPs) for patients with pre-dialysis chronic kidney disease (CKD) and new-onset cardiovascular disease (CVD) after initiating dialysis is unclear.

METHODS

We conducted a retrospective cohort study between January 1, 2011 and December 31, 2018, evaluating CKD patients who were divided into two groups based on whether or not they participated in IEPs. The primary outcome was a new-onset CVD event after initiating dialysis. Cumulative incidence function was used to describe new-onset CVD considering the competing outcome of death. Additionally, Cox proportional hazards models were used to estimate the hazard ratio of new-onset CVD between IEP and non-IEP groups.

RESULTS

Of the 493 patients, 131 (26.6%) patients had participated in IEPs. The IEP group had a significantly longer duration of CKD management by nephrologists (median 142 vs. 115 days, P = 0.007), lower rate of emergency hospital admissions (9.9% vs. 27.1%, P < 0.001), better ability to perform activities of daily living (Grade J; 81.6% vs. 69.1%, P = 0.046), higher rate of pre-placement of permanent vascular access or peritoneal dialysis catheters (82.4% vs. 59.4%, P < 0.001), and a higher serum albumin level at the beginning of dialysis (3.5 ± 0.5 vs. 3.3 ± 0.6 g/dL, P < 0.001). The cumulative incidence of new-onset CVD at three years after initiating dialysis in the IEP and non-IEP groups was 16.9% and 22.5%, respectively. The hazard ratio for new-onset CVD after initiating dialysis in the IEP group was 0.63 (95% CI: 0.41-0.97, P = 0.036).

CONCLUSION

IEPs were associated with a lower rate of new-onset CVD after initiating dialysis.

Role of standard HLA mismatch in modifying associations between non-pharmacologic risk factors and solid organ malignancy after kidney transplantation

BACKGROUND

Human leukocyte antigen mismatch(es) (HLA-mm) between donors and recipients has not been extensively studied either as a risk factor for solid organ malignancy (SOM) or as a modifier of associations between nonpharmacologic risk factors and SOM in kidney transplant recipients (KTRs).

METHODS

In a secondary analysis from a previous study, 166,256 adult KTRs in 2000-2018 who survived the first 12 months post-transplant free of graft loss or malignancy were classified into 0, 1-3, and 4-6 standard HLA-mm cohorts. Multivariable cause-specific Cox regressions analyzed the risks of SOM and all-cause mortality (ac-mortality) in 5 years following the first KT year. Comparisons of associations between SOM and risk factors in HLA mismatch cohorts were made by estimating the ratios of adjusted hazard ratios.

RESULTS

Compared with 0 HLA-mm, 1-3 HLA-mm was not associated, and 4-6 HLA-mm was equivocally associated with increased risk of SOM [hazard ratio, (HR) = 1.05, 95%, confidence interval (CI) = 0.94-1.17 and HR = 1.11, 95% CI = 1.00-1.34, respectively]. Both 1-3 HLA-mm and 4-6 HLA-mm were associated with increased risk of ac-mortality compared with 0 HLA mm [hazard ratio (HR) = 1.12, 95%, Confidence Interval (CI) = 1.08-1.18) and (HR = 1.16, 95% CI = 1.09-1.22), respectively]. KTR's history of pre-transplant cancer, age 50-64, and >/=65 years were associated with increased risks of SOM and ac-mortality in all HLA mismatch cohorts. Pre-transplant dialysis >2 years, diabetes as the primary renal disease, and expanded or standard criteria deceased donor transplantation were risk factors for SOM in the 0 and 1-3 HLA-mm cohorts and of ac-mortality in all HLA-mm cohorts. KTRs male sex or history of previous kidney transplant was a risk factor for SOM in the 1-3 and 4-6 HLA-mm cohorts and of ac-mortality in all HLA-mm cohorts.

CONCLUSION

Direct association between SOM and the degree of HLA mismatching is equivocal and limited to the 4-6 HLA-mm stratum; however, the degree of HLA mismatching has significant modifying effects on the associations between specific nonpharmacologic risk factors and SOM in KTRs.

Blood pressure management and long-term outcomes in kidney transplantation: a holistic view over a 35-year period

INTRODUCTION

Hypertension is a burden for most kidney transplant recipients. Whether respect of hypertension guidelines results in better outcomes is unknown.

METHODS

In this multicenter study, office blood pressure at 12 months following transplantation (i.e., after > 20 outpatient visits), and survival were assessed over 35 years among 2004 consecutive kidney transplant recipients who received a first kidney graft from 1985 to 2019 (follow-up: 26,232 patient-years).

RESULTS

Antihypertensive medications were used in 1763/2004 (88.0%) patients. Renin-angiotensin-system blockers were used in 35.6% (47.1% when proteinuria was > 0.5 g/day) and calcium-channel blockers were used in 6.0% of patients. Combined treatment including renin-angiotensin-system-blockers, calcium-channel blockers and diuretics was used in 15.4% of patients receiving ≥ 3 antihypertensive drugs. Blood pressure was controlled in 8.3%, 18.8% and 43.1%, respectively, depending on definition (BP < 120/80, < 130/80, < 140/90 mmHg, respectively) and has not improved since the year 2001. Two-thirds of patients with uncontrolled blood pressure received < 3 antihypertensive classes. Low sodium intake < 2 g/day (vs ≥ 2) was not associated with better blood pressure control. Uncontrolled blood pressure was associated with lower patient survival (in multivariable analyses) and graft survival (in univariate analyses) vs controlled hypertension or normotension. Low sodium intake and major antihypertensive classes had no influence on patient and graft survival.

CONCLUSIONS

Pharmacological recommendations and sodium intake reduction are poorly respected, but even when respected, do not result in better blood pressure control, or patient or graft survival. Uncontrolled blood pressure, not the use of specific antihypertensive classes, is associated with reduced patient, and to a lesser extent, reduced graft survival, even using the 120/80 mmHg cut-off.

Risk Factors of Dental Caries in the Thai Population: The Retrospective Cohort Study

Aim

The aim of this retrospective cohort study was to determine the risk factors associated with the occurrence of dental caries increments in Thai dental patients.

Materials and Methods

The dental chart records of 500 patients who visited the Department of Advanced General Dentistry, Mahidol University during 2003-2013 were included in this research. Risk factors such as age, gender, medical history, marital status, routine oral checkup, oral appliance usage, initial and final records of decayed (DT)-missing-filled (DMF-T), dental history of tooth extraction due to caries, xerostomia, presence of visible plaque, presence of interproximal restoration, and caries risk level were retrieved from dental records. Cox proportional hazard regression model was used to determine the association of caries risk factors and new dental caries increments.

Results

The results indicated that the rate of incidence of new dental caries was 2.1 per 100 person-month. In the multivariate hazard model, past caries experience in more than three teeth (adjusted hazard ratio: 2.29, 95%CI: 1.53-3.44) and xerostomia (adjusted hazard ratio: 4.47, 95%CI: 1.82-10.98) were independent risk factors of dental caries increments. Other factors, such as demographic data, physical factors, clinical factors, and other contributing factors, were not associated with the incidence of new dental caries.

Conclusion

The presence of past caries experience and xerostomia were predictors of the occurrence of new dental caries.

Kidney function at 3 months after acute kidney injury is an unreliable indicator of subsequent kidney dysfunction: the NARA-AKI Cohort Study

BACKGROUND

The relationship between kidney function at 3 months after acute kidney injury (AKI) and kidney function prognosis has not been characterized.

METHODS

This retrospective cohort study included adults who underwent noncardiac surgery under general anesthesia. Exclusion criteria included obstetric or urological surgery, missing data and preoperative dialysis. Linear mixed-effects models were used to compare estimated glomerular filtration rate (eGFR) slopes in patients with and without AKI. Multivariable Cox proportional hazard models were used to examine the associations of AKI with incident chronic kidney disease (CKD) and decline in eGFR ≥30%.

RESULTS

Among 5272 patients, 316 (6.0%) developed AKI. Among 1194 patients with follow-up creatinine values, eGFR was stable or increased in patients with and without AKI at 3 months postoperatively and declined thereafter. eGFR decline after 3 months postoperatively was faster among patients with AKI than among patients without AKI (P = .09). Among 938 patients without CKD-both at baseline and at 3 months postoperatively-226 and 161 developed incident CKD and a decline in eGFR ≥30%, respectively. Despite adjustment for eGFR at 3 months, AKI was associated with incident CKD {hazard ratio [HR] 1.73 [95% confidence interval (CI) 1.06-2.84]} and a decline in eGFR ≥30% [HR 2.41 (95% CI 1.51-3.84)].

CONCLUSIONS

AKI was associated with worse kidney outcomes, regardless of eGFR at 3 months after surgery. Creatinine-based eGFR values at 3 months after AKI might be affected by acute illness-induced loss of muscle mass. Kidney function might be more accurately evaluated much later after surgery or using cystatin C values.

Initiation of renin-angiotensin system inhibitors and first complete remission in patients with primary nephrotic syndrome: a nationwide cohort study

BACKGROUND

Evidence on renin-angiotensin system inhibitors (RASis) effect in reducing urinary protein levels in patients with nephrotic syndrome is insufficient. We determined whether RASis can induce complete remission (CR) in patients on immunosuppressive therapy.

METHODS

This cohort study included 84 adults (median age, 65 years; males, 57%) with primary nephrotic syndrome (excluding minimal change disease) not receiving RASis during enrollment in the Japanese Nephrotic Syndrome Cohort Study from January 2009 to December 2010, and were followed up for 5 years. Exposure and outcome were RASi initiation and first CR, respectively. Marginal structural models and Poisson regression were used to account for time-varying covariates and estimate causal effects of RASis on CR.

RESULTS

Overall, 51 (61%), 73 (87%), and 55 (66%) patients had membranous nephropathy, were prescribed immunosuppressive agents at baseline (1-month post-renal biopsy and/or at start of immunosuppressive therapy), and were prescribed RASis during the study period, respectively. Sixty-five patients experienced first CR (incidence rate, 5.05/100 person-months). RASi use was associated with a higher (adjusted incidence rate ratio [aIRR] 2.27, 95% confidence interval [CI] 1.06-4.84), and lower (aIRR: 0.17, 95% CI 0.04-0.68) first CR in patients with membranous nephropathy and other pathologies, respectively.

CONCLUSION

RASis are beneficial as adjuvant therapy for inducing remission in patients with membranous nephropathy.

End-diastolic velocity mediates the relationship between renal resistive index and the risk of death

OBJECTIVE

Renal resistive index predicts the risk of death in many populations but the mechanism linking renal resistive index and death remains elusive. Renal resistive index is derived from end-diastolic velocity (EDV) and peak systolic velocity (PSV). However, the predictive value of EDV or PSV considered alone is unknown.

METHODS

We conducted a retrospective analysis of 2362 consecutive patients who received a kidney transplant from 1985 to 2017. EDV and PSV were measured at 3 months after transplantation, renal resistive index was calculated, and the risk of death was assessed [median follow-up: 6.25 years (0.25-29.15); total observation period: 13 201 patient-years].

RESULTS

Doppler indices were available in 1721 of 2362 (78.9%) patients (exclusions: 113 who died or returned to dialysis before, 427 with no Doppler studies, 27 with renal artery stenosis, 74 missing values). Among them, 279 (16.4%) had diabetes before transplantation. Mean age was 51.5 ± 14.7, 1097 (63.7%) were male. During follow-up, 217 of 1721 (12.6%) patients died. Renal resistive index and EDV shared many determinants (notably systolic, diastolic and pulse pressure, recipient age and diabetes) unlike renal resistive index and PSV. EDV used as a binary [lowest tertile vs. higher values: (hazard ratio: 2.57 (1.96-3.36), P  < 0.001)] and as a continuous (the lower EDV, the greater the risk of death) variable was significantly associated with the risk of death. This finding was confirmed in multivariable analyses. Prediction of similar magnitude was found for renal resistive index. No association was found between PSV used as a binary or a continuous variable and the risk of death.

CONCLUSION

Low EDV explains high renal resistive index, and the mechanism-linking renal resistive index to the risk of death is through low EDV.

A Health Survey-Based Prediction Equation for Incident CKD

BACKGROUND

Prediction tools that incorporate self-reported health information could increase CKD awareness, identify modifiable lifestyle risk factors, and prevent disease. We developed and validated a survey-based prediction equation to identify individuals at risk for incident CKD (eGFR <60 ml/min per 1.73 m2), with and without a baseline eGFR.

METHODS

A cohort of adults with an eGFR ≥70 ml/min per 1.73 m2 from Ontario, Canada, who completed a comprehensive general population health survey between 2000 and 2015 were included (n=22,200). Prediction equations included demographics (age, sex), comorbidities, lifestyle factors, diet, and mood. Models with and without baseline eGFR were derived and externally validated in the UK Biobank (n=15,522). New-onset CKD (eGFR <60 ml/min per 1.73 m2) with ≤8 years of follow-up was the primary outcome.

RESULTS

Among Ontario individuals (mean age, 55 years; 58% women; baseline eGFR, 95 (SD 15) ml/min per 1.73 m2), new-onset CKD occurred in 1981 (9%) during a median follow-up time of 4.2 years. The final models included lifestyle factors (smoking, alcohol, physical activity) and comorbid illnesses (diabetes, hypertension, cancer). The model was discriminating in individuals with and without a baseline eGFR measure (5-year c-statistic with baseline eGFR: 83.5, 95% confidence interval [CI], 82.2 to 84.9; without: 81.0, 95% CI, 79.8 to 82.4) and well calibrated. In external validation, the 5-year c-statistic was 78.1 (95% CI, 74.2 to 82.0) and 66.0 (95% CI, 61.6 to 70.4), with and without baseline eGFR, respectively, and maintained calibration.

CONCLUSIONS

Self-reported lifestyle and health behavior information from health surveys may aid in predicting incident CKD.

PODCAST

This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast.aspx?p=CJASN&e=2023_01_10_CJN05650522.mp3.

Long-term impact of cardiorenal syndromes on major outcomes based on their chronology: a comprehensive French nationwide cohort study

BACKGROUND

Cardiorenal syndromes (CRSs) are reputed to result in worse prognosis than isolated heart failure (HF) and chronic kidney disease (CKD). Whether it is true for all major outcomes over the long-term regardless of CRS chronology (simultaneous, cardiorenal and renocardiac CRS) is unknown.

METHODS

The 5-year adjusted risk of major outcomes was assessed in this nationwide retrospective cohort study in all 385 687 with either CKD or HF (out of 5 123 193 patients who were admitted in a French hospital in 2012).

RESULTS

Overall, 84.0% patients had HF and 8.9% had CKD (they had similar age, sex ratio, diabetes and hypertension prevalence), while 7.1% had CRS (cardiorenal: 44.6%, renocardiac: 14.5%, simultaneous CRS: 40.8%).The incidence of major outcomes was 57.3%, 53.0%, 79.2% for death; 18.8%, 10.9%, 27.5% for cardiovascular death; 52.6%, 34.7%, 64.3% for HF; 6.2%, 5.5%, 5.6% for myocardial infarction (MI); 6.1%, 5.8%, 5.3% for ischaemic stroke; and 23.1%, 4.8%, 16.1% for end-stage kidney disease (ESKD) for isolated CKD, isolated HF and CRS, respectively.As compared with isolated CKD or HF, the risk of death, cardiovascular death and HF was markedly increased in CRS, the worse phenotype being cardiorenal CRS, while the increased risk of MI and ischaemic stroke associated with CRS subtypes was statistically but not clinically significant. As compared with isolated CKD, the risk of ESKD was similar for cardiorenal CRS only and marginally increased for renocardiac and simultaneous CRS. We could not find a synergy between HF and CKD on major clinical outcomes in the whole population (n = 5 123 193 patients).

CONCLUSIONS

The additional impact of CRS versus isolated HF or CKD on long-term kidney and cardiovascular risk is highly heterogenous, depending of the event considered and CRS chronology. No synergy between HF and CKD could be demonstrated.

Transplant outcomes of 100 cases of living-donor ABO-incompatible kidney transplantation

BACKGROUND

Although ABO-incompatible (ABOi) kidney transplantation (KT) has been performed successfully, a standard preconditioning regimen has not been established. Based on the initial antidonor ABO antibody titers, an individualized preconditioning regimen is developed, and this study explored the efficacy and safety of the regimen.

METHODS

From September 1, 2014, to September 1, 2020, we performed 1668 consecutive living-donor KTs, including 100 ABOi and 1568 ABO-compatible (ABOc) KTs. ABOi KT recipients (KTRs) with a lower antibody titer (≤1:8) were administered oral immunosuppressive drugs (OIs) before KT, while patients with a medium titer (1:16) received OIs plus antibody-removal therapy (plasma exchange/double-filtration plasmapheresis), patients with a higher titer (≥1:32) were in addition received rituximab (Rit). Competing risk analyses were conducted to estimate the cumulative incidence of infection, acute rejection (AR), graft loss, and patient death.

RESULTS

After propensity score analyses, 100 ABOi KTRs and 200 matched ABOc KTRs were selected. There were no significant differences in graft and patient survival between the ABOi and ABOc groups (P  = 0.787, P  = 0.386, respectively). After using the individualized preconditioning regimen, ABOi KTRs showed a similar cumulative incidence of AR (10.0% υs . 10.5%, P  = 0.346). Among the ABOi KTRs, the Rit-free group had a similar cumulative incidence of AR ( P  = 0.714) compared to that of the Rit-treated group. Multivariate competing risk analyses revealed that a Rit-free regimen reduced the risk of infection (HR: 0.31; 95% CI: 0.12-0.78, P  = 0.013). Notably, antibody titer rebound was more common in ABOi KTRs receiving a Rit-free preconditioning regimen ( P  = 0.013) than those receiving Rit. ABOi KTRs with antibody titer rebound had a 2.72-fold risk of AR (HR: 2.72, 95% CI: 1.01-7.31, P  = 0.048). ABOi KTRs had similar serum creatinine and estimated glomerular filtration rate compared to those of ABOc KTRs after the first year.

CONCLUSIONS

An individualized preconditioning regimen can achieve comparable graft and patient survival rates in ABOi KT with ABOc KT. Rit-free preconditioning effectively prevented AR without increasing the risk of infectious events in those with lower initial titers; however, antibody titer rebound should be monitored.

Variability of body mass index and risks of prostate, lung, colon, and ovarian cancers

Objective

We investigated the association between cancer incidence and body mass index (BMI) variability calculated from the recall of weight at decades of age by participants in the USA Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial.

Methods

A total of 89,822 individuals' BMI were recorded as recalled the participant's aged 30, 40, 50, 60, 70 years, and baseline. BMI variability was assessed using four indices: SD, coefficient of variation (CV), variability independent of the mean (VIM), and average real variability (ARV). The multivariate Cox regression analysis was performed to calculate hazard ratios (HRs) of these measures for incident cancers and corresponding 95% CIs.

Results

During the median follow-up of 11.8 years, there were newly diagnosed 5,012 cases of prostate cancer, 792 cases of lung cancer, 994 cases of colon cancer, and 132 cases of ovarian cancer. Compared with the lowest quartile (Q1) group, the highest quartile (Q4) group of BMI variability indices was associated with increased lung cancer risk, including BMI_SD (HR, 1.58; 95% CI, 1.17-2.12), BMI_CV (HR, 1.46; 95% CI, 1.10-1.94), BMI_VIM (HR, 1.73; 95% CI, 1.33-2.25), and BMI_ARV (HR, 2.17; 95% CI, 1.62-2.91). Associations between BMI variability and prostate, colon, and ovarian cancer incidences were of limited significance.

Conclusion

The findings imply that maintaining a stable weight across adulthood is associated with a decreased incidence of lung cancer.

Incidence rate patterns, cumulative incidence, and time trends for moderate and severe albuminuria in individuals diagnosed with type 1 diabetes aged 0-14 years: a population-based retrospective cohort study

BACKGROUND

The incidence and temporal trends of moderate and severe albuminuria during recent decades are poorly described in type 1 diabetes. We aimed to assess diabetes duration-specific incidence rates, cumulative incidence, and secular trends of albuminuria in type 1 diabetes in Finland.

METHODS

We conducted a population-based, retrospective cohort study of a stratified random sample (n=1500) of all individuals diagnosed with type 1 diabetes before age 15 years during 1970-99 in Finland. The sampling frame was the database of the Finnish Institute for Health and Welfare. Individuals with an atypical clinical course, presentation of non-diabetic kidney disease, insufficient albumin excretion rate measurements, or unavailable medical records were excluded (final sample n=1430). Study participants were followed up until death, the event of interest (moderate or severe albuminuria or kidney failure), or the most recent event-free date. Medical records retrieved up to Dec 31, 2020 were systematically reviewed for albuminuria determinations. Moderate and severe albuminuria were categorised on the basis of international reference limits (two of three consecutive urine samples). Kidney failure was defined as dialysis treatment or kidney transplant. Cohorts defined by calendar year of diabetes diagnosis (1970-79, 1980-89, and 1990-99) were assessed. Patterns of duration-specific incidences were evaluated by fitting generalised additive models to the data, which were split into multiple observations of half-year duration. Cumulative incidences were calculated with Kaplan-Meier analysis. In analyses with kidney failure as the endpoint, competing risk for mortality was incorporated.

FINDINGS

In our stratified random sample, 462 individuals were diagnosed with diabetes in 1970-79, 481 were diagnosed in 1980-89, and 487 were diagnosed in 1990-99. The incidence rate pattern of severe albuminuria changed over time; a peak at 15-19 years since diabetes onset in the 1970-79 cohort was not replicated in those diagnosed later. In the combined 1980-99 diagnosis-year cohorts, the incidence rate rose during the first 14 years after diabetes onset, after which it levelled off to a plateau. Between the 1970-79 and 1980-89 diabetes diagnosis cohorts, the cumulative incidence of severe albuminuria had approximately halved (hazard ratio [HR] 0·55 [95% CI 0·42-0·72] with the 1970-79 cohort as reference, p<0·0001), whereas, between the 1980-89 and 1990-99 cohorts, no further decrease was observed (HR 0·83 [0·54-1·26] with the 1980-89 cohort as reference, p=0·38). The 25-year cumulative incidence for severe albuminuria was 26·8% (22·6-30·8) in the 1970-79 diagnosis cohort, 12·0% (9·0-15·0) in the 1980-89 cohort, and 10·8% (6·7-14·6) in the 1990-99 cohort. 15 years after onset of severe albuminuria, cumulative progression rate from severe albuminuria to kidney failure was 35·2% (27·4-43·0) in the 1970-79 cohort and 35·6% (24·3-47·0) in the 1980-99 cohorts combined (Gray's test p=0·37). In the cohorts with data on moderate albuminuria (1980-89 and 1990-99), cumulative incidence of moderate albuminuria showed no calendar effect between the earlier and later cohorts (HR 0·99 [0·78-1·28] with the 1980-89 cohort as reference, p=0·97). The incidence rate of moderate albuminuria increased until 10 years after diabetes onset, then remained mostly stable until starting to decrease at around 25 years after diabetes onset.

INTERPRETATION

Our analyses show that the cumulative incidence of severe albuminuria has decreased between 1970-79 and 1980-99; however, whether this decrease solely denotes a delay in albuminuria, or also a true prevention of albuminuria, needs to be investigated further. Nevertheless, diabetic kidney disease remains a significant complication of type 1 diabetes. Due to the robust association of diabetic kidney disease with premature mortality, novel therapies to improve prognosis are needed.

FUNDING

Folkhälsan Research Foundation, Medical Society of Finland, Wilhelm and Else Stockmann Foundation, Finnish Diabetes Research Foundation, Waldemar von Frenckell Foundation, Liv och Hälsa Society, Academy of Finland, and Novo Nordisk Foundation.

TRANSLATIONS

For the Finnish and Swedish translations of the abstract see Supplementary Materials section.

Vitamin K status, all-cause mortality, and cardiovascular disease in adults with chronic kidney disease: the Chronic Renal Insufficiency Cohort

BACKGROUND

Vascular calcification contributes to cardiovascular disease (CVD) and mortality in individuals with chronic kidney disease (CKD). Vitamin K-dependent proteins function as calcification inhibitors in vascular tissue.

OBJECTIVES

We sought to determine the association of vitamin K status with mortality and CVD events in adults with CKD.

METHODS

Plasma dephospho-uncarboxylated matrix gla protein ((dp)ucMGP), which increases when vitamin K status is low, and plasma phylloquinone (vitamin K1), which decreases when vitamin K status is low, were measured in 3066 Chronic Renal Insufficiency Cohort participants (median age = 61 y, 45% female, 41% non-Hispanic black, median estimated glomerular filtration rate [eGFR] = 41 mL/min/1.73m2). The association of vitamin K status biomarkers with all-cause mortality and atherosclerotic-related CVD was determined using multivariable Cox proportional hazards regression.

RESULTS

There were 1122 deaths and 599 atherosclerotic CVD events over the median 12.8 follow-up years. All-cause mortality risk was 21-29% lower among participants with plasma (dp)ucMGP <450 pmol/L (n = 2361) compared with those with plasma (dp)ucMGP ≥450 pmol/L (adjusted HRs [95% CIs]: <300 pmol/L = 0.71 [0.61, 0.83], 300-449 pmol/L = 0.77 [0.66, 0.90]) and 16-19% lower among participants with plasma phylloquinone ≥0.50 nmol/L (n = 2421) compared to those with plasma phylloquinone <0.50 nmol/L (adjusted HRs: 0.50, 0.99 nmol/L = 0.84 [0.72, 0.99], ≥1.00 nmol/L = 0.81 [0.70, 0.95]). The risk of atherosclerotic CVD events did not significantly differ across plasma (dp)ucMGP or phylloquinone categories.

CONCLUSIONS

Two biomarkers of vitamin K status were associated with a lower all-cause mortality risk but not atherosclerotic CVD events. Additional studies are needed to clarify the mechanism underlying this association and evaluate the impact of improving vitamin K status in people with CKD.

Nutritional disorder evaluated by geriatric nutritional risk index predicts death after hospitalization for infection in patients undergoing maintenance hemodialysis

OBJECTIVE

Infection is related to higher rate of hospitalization and subsequent death in patients undergoing hemodialysis. Limited data are available about factors associated with death after hospitalization for infection. Nutritional disorder also known as protein-energy wasting is profoundly associated with poor consequences. Geriatric nutritional risk index (GNRI) is a simple but useful nutritional screening tool to predict mortality. We examined whether GNRI could predict hospitalization for infection and subsequent death.

DESIGN AND METHODS

This was a prospective cohort study in hemodialysis patients. The predictor was GNRI. The patients were divided into tertiles of GNRI (T1 to T3), with the highest tertile of T3 as referent. The outcomes of interest were all-cause mortality, hospitalization for infection and subsequent death.

RESULTS

Of 518 patients, 107 patients died (median follow-up period, 5.0 years; interquartile range 3.6-5.0) and 169 patients experienced new hospitalization for infection (median follow-up period, 4.5 years; interquartile range 3.4-5.0) during the follow-up period from December 2004 to December 2009. A lower GNRI was a significant predictor for all-cause mortality in multivariable Cox models (hazard ratio [HR] 2.9, 95% confidential interval [CI] 1.5-5.5, p < 0.001 for T1 vs. T3). However, GNRI was not associated with hospitalization for infection in multivariable Fine-Gray models with death as a competing risk (subdistributional HR 1.5, 95% CI 1.0-2.3, p = 0.056 for T1 vs. T3). After hospitalization for infection, 38 patients died during subsequent 2.5-year follow-up period. GNRI was a significant predictor of death after hospitalization for infection in multivariable Cox models (HR 2.7, 95% CI 1.3-5.6, p = 0.006 for T1 vs. T2+T3).

CONCLUSIONS

A lower GNRI predicted a higher risk of all-cause mortality but not hospitalization for infection. However, a lower GNRI was significantly associated with a higher risk of mortality after hospitalization for infection. These findings suggest that long-term mortality after hospitalization for infection was predicted by nutritional disorder evaluated by GNRI.

Identification of Distinct Clinical Subphenotypes in Critically Ill Patients With COVID-19

Background

Subphenotypes have been identified in patients with sepsis and ARDS and are associated with different outcomes and responses to therapies.

Research Question

Can unique subphenotypes be identified among critically ill patients with COVID-19?

Study Design and Methods

Using data from a multicenter cohort study that enrolled critically ill patients with COVID-19 from 67 hospitals across the United States, we randomly divided centers into discovery and replication cohorts. We used latent class analysis independently in each cohort to identify subphenotypes based on clinical and laboratory variables. We then analyzed the associations of subphenotypes with 28-day mortality.

Results

Latent class analysis identified four subphenotypes (SP) with consistent characteristics across the discovery (45 centers; n = 2,188) and replication (22 centers; n = 1,112) cohorts. SP1 was characterized by shock, acidemia, and multiorgan dysfunction, including acute kidney injury treated with renal replacement therapy. SP2 was characterized by high C-reactive protein, early need for mechanical ventilation, and the highest rate of ARDS. SP3 showed the highest burden of chronic diseases, whereas SP4 demonstrated limited chronic disease burden and mild physiologic abnormalities. Twenty-eight-day mortality in the discovery cohort ranged from 20.6% (SP4) to 52.9% (SP1). Mortality across subphenotypes remained different after adjustment for demographics, comorbidities, organ dysfunction and illness severity, regional and hospital factors. Compared with SP4, the relative risks were as follows: SP1, 1.67 (95% CI, 1.36-2.03); SP2, 1.39 (95% CI, 1.17-1.65); and SP3, 1.39 (95% CI, 1.15-1.67). Findings were similar in the replication cohort.

Interpretation

We identified four subphenotypes of COVID-19 critical illness with distinct patterns of clinical and laboratory characteristics, comorbidity burden, and mortality.

Sex Differences in Cardiovascular Outcomes in CKD: Findings From the CRIC Study

RATIONALE & OBJECTIVE

Cardiovascular events are less common in women than men in general populations; however, studies in chronic kidney disease (CKD) are less conclusive. We evaluated sex-related differences in cardiovascular events and death in adults with CKD.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

1,778 women and 2,161 men enrolled in the Chronic Renal Insufficiency Cohort (CRIC).

EXPOSURE

Sex (women vs men).

OUTCOME

Atherosclerotic composite outcome (myocardial infarction, stroke, or peripheral artery disease), incident heart failure, cardiovascular death, and all-cause death.

ANALYTICAL APPROACH

Cox proportional hazards regression.

RESULTS

During a median follow-up period of 9.6 years, we observed 698 atherosclerotic events (women, 264; men, 434), 762 heart failure events (women, 331; men, 431), 435 cardiovascular deaths (women, 163; men, 274), and 1,158 deaths from any cause (women, 449; men, 709). In analyses adjusted for sociodemographic, clinical, and metabolic parameters, women had a lower risk of atherosclerotic events (HR, 0.71 [95% CI, 0.57-0.88]), heart failure (HR, 0.76 [95% CI, 0.62-0.93]), cardiovascular death (HR, 0.55 [95% CI, 0.42-0.72]), and death from any cause (HR, 0.58 [95% CI, 0.49-0.69]) compared with men. These associations remained statistically significant after adjusting for cardiac and inflammation biomarkers.

LIMITATIONS

Assessment of sex hormones, which may play a role in cardiovascular risk, was not included.

CONCLUSIONS

In a large, diverse cohort of adults with CKD, compared with men, women had lower risks of cardiovascular events, cardiovascular mortality, and mortality from any cause. These differences were not explained by measured cardiovascular risk factors.

Risk Factors for CKD Progression: Overview of Findings from the CRIC Study

The Chronic Renal Insufficiency Cohort (CRIC) Study is an ongoing, multicenter, longitudinal study of nearly 5500 adults with CKD in the United States. Over the past 10 years, the CRIC Study has made significant contributions to the understanding of factors associated with CKD progression. This review summarizes findings from longitudinal studies evaluating risk factors associated with CKD progression in the CRIC Study, grouped into the following six thematic categories: (1) sociodemographic and economic (sex, race/ethnicity, and nephrology care); (2) behavioral (healthy lifestyle, diet, and sleep); (3) genetic (apoL1, genome-wide association study, and renin-angiotensin-aldosterone system pathway genes); (4) cardiovascular (atrial fibrillation, hypertension, and vascular stiffness); (5) metabolic (fibroblast growth factor 23 and urinary oxalate); and (6) novel factors (AKI and biomarkers of kidney injury). Additionally, we highlight areas where future research is needed, and opportunities for interdisciplinary collaboration.

Overdose mortality is reducing the gains in life expectancy of antiretroviral-treated people living with HIV in British Columbia, Canada

BACKGROUND

A remarkable reduction in AIDS-related mortality has been achieved through the widespread use of triple combination antiretroviral therapy, considerably increasing the life expectancy of people living with HIV (PLWH). However, these survival gains are now at risk in North America due to an unprecedented public health emergency: the deadly drug overdose epidemic. Drug overdoses are now the leading cause of unintentional death in British Columbia (BC), Canada and the United States due to synthetic opioids (e.g., fentanyl) in illegal markets. This manuscript aimed to estimate the effect of overdose mortality on life expectancy and identify covariates associated with the hazard for overdose mortality in the presence of competing risk among PLWH in BC.

METHODS

Those eligible were aged ≥20 years, initiated antiretroviral therapy from 1-Apr-1996 to 30-Dec-2017, and were followed until 31-Dec-2017, last contact or death date. We estimated the potential gains in life expectancy from abridged life tables. We modelled the association between covariates and the cause-specific hazard for overdose mortality, accounting for mortality of other causes as a competing risk.

RESULTS

Among the 10,362 PLWH, 3% experienced overdose mortality. The life expectancy at age 20 increased by 8.7 years from 2002-2007 to 2008-2013 compared to only 3.0 years from 2008-2013 to 2014-2017. The potential gain in life expectancy was 3.3 years at age 20 during the ongoing overdose epidemic (2014-2017). There were gender differences in life expectancies throughout the study period. People who have ever injected drugs, women and viral load monitoring non-compliance were key covariates associated with an increased hazard of overdose mortality.

CONCLUSION

Survival gains among PLWH have been considerably reduced due to the ongoing overdose epidemic.

Early changes in renal resistive index and mortality in diabetic and nondiabetic kidney transplant recipients: a cohort study

Background

Renal resistive index (RI) predicts mortality in renal transplant recipients (RTR). However, its predictive value may be different according to the time of measurement. We analysed RI changes between 1 month and 3 months after transplantation and its predictive value for death with a functioning graft (DWFG).

Methods

We conducted a retrospective study in 1685 RTR between 1985 and 2017. The long-term predictive value of changes in RI value from 1 month to 3 months was assessed in diabetic and non-diabetic RTR.

Results

Best survival was observed in RTR with RI < 0.70 both at 1 and 3 months, and the worst survival was found in RTR with RI ≥ 0.70 both at 1 and 3 months (HR = 3.77, [2.71–5.24], p < 0.001). The risk of DWFG was intermediate when RI was < 0.70 at 1 month and ≥ 0.70 at 3 months (HR = 2.15 [1.29–3.60], p = 0.003) and when RI was ≥0.70 at 1 month and < 0.70 at 3 months (HR = 1.90 [1.20–3.03], p = 0.006).

In diabetic RTR, RI was significantly associated with an increased risk of death only in those with RI < 0.70 at 1 month and ≥ 0.70 at 3 months (HR = 4.69 [1.07–20.52], p = 0.040). RI considered as a continuous variable at 1 and 3 months was significantly associated with the risk of DWFG in nondiabetic but not in diabetic RTR.

Conclusion

RI changes overtime and this impacts differently diabetic and nondiabetic RTR. RI short-term changes have a strong prognosis value and refines the risk of DWFG associated with RI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02263-8.

The association between renal resistive index and premature mortality after kidney transplantation is modified by pre-transplant diabetes status: a cohort study

BACKGROUND

Renal resistive index (RI) predicts mortality in renal transplant recipients, but we do not know whether this is true in diabetic patients. The objective of this study was to analyse the long-term predictive value of RI for death with a functioning graft (DWFG) in renal transplant recipients with or without pre-transplant diabetes.

METHODS

We conducted a retrospective study in 1800 renal transplant recipients between 1985 and 2017 who were followed for up to 30 years (total observation period: 14 202 patient years). Donor and recipient characteristics at time of transplantation and at 3 months were reviewed. The long-term predictive value of RI for DWFG and the age-RI and arterial pressure-RI relationships were assessed.

RESULTS

A total of 284/1800 (15.7%) patients had diabetes mellitus before transplantation. RI was <0.75 in 1327/1800 patients (73.7%). High RI was associated with a higher risk of DWFG in non-diabetic patients [hazard ratio (HR) = 3.39, 95% confidence interval 2.50-4.61; P < 0.001], but not in patients with pre-transplant diabetes (HR = 1.25, 0.70-2.19; P = 0.39), even after multiple adjustments. There was no interaction between diabetes and age. In contrast, there was an interaction between RI and pulse pressure.

CONCLUSION

Our study indicates that RI is not a predictor of DWFG in diabetic renal transplant recipients, in contrast to non-diabetic recipients. These findings could be due to a different age-RI or pulse pressure-RI relationship.

Predicting mortality in hemodialysis patients using machine learning analysis

Background

Besides the classic logistic regression analysis, non-parametric methods based on machine learning techniques such as random forest are presently used to generate predictive models. The aim of this study was to evaluate random forest mortality prediction models in haemodialysis patients.

Methods

Data were acquired from incident haemodialysis patients between 1995 and 2015. Prediction of mortality at 6 months, 1 year and 2 years of haemodialysis was calculated using random forest and the accuracy was compared with logistic regression. Baseline data were constructed with the information obtained during the initial period of regular haemodialysis. Aiming to increase accuracy concerning baseline information of each patient, the period of time used to collect data was set at 30, 60 and 90 days after the first haemodialysis session.

Results

There were 1571 incident haemodialysis patients included. The mean age was 62.3 years and the average Charlson comorbidity index was 5.99. The mortality prediction models obtained by random forest appear to be adequate in terms of accuracy [area under the curve (AUC) 0.68–0.73] and superior to logistic regression models (ΔAUC 0.007–0.046). Results indicate that both random forest and logistic regression develop mortality prediction models using different variables.

Conclusions

Random forest is an adequate method, and superior to logistic regression, to generate mortality prediction models in haemodialysis patients.

Kidney Clearance of Secretory Solutes Is Associated with Progression of CKD: The CRIC Study

BACKGROUND

The secretion of organic solutes by the proximal tubules is an essential intrinsic kidney function. However, the clinical significance of the kidney's clearance of tubular secretory solutes is uncertain.

METHODS

In this prospective cohort study, we evaluated 3416 participants with CKD from the Chronic Renal Insufficiency Cohort (CRIC) study. We measured plasma and 24-hour urine concentrations of endogenous candidate secretory solutes at baseline, using targeted liquid chromatography-tandem mass spectrometry. The study defined CKD progression by a ≥50% decline in the eGFR, initiation of maintenance dialysis, or kidney transplantation. We used Cox proportional hazards regression to test associations of secretory-solute clearances with CKD progression and mortality, adjusting for eGFR, albuminuria, and other confounding characteristics.

RESULTS

Participants in this ancillary study had a mean age of 58 years and 41% were black; the median eGFR was 43 ml/min per 1.73 m2. After adjustment, lower kidney clearances of six solutes-kynurenic acid, pyridoxic acid, indoxyl sulfate, xanthosine, isovalerylglycine, and cinnamoylglycine-were associated with significantly greater risks of CKD progression, with clearance of kynurenic acid, a highly protein-bound solute, having the strongest association. Lower clearances of isovalerylglycine, tiglylglycine, hippurate, and trimethyluric acid were significantly associated with all-cause mortality after adjustment.

CONCLUSIONS

We found lower kidney clearances of endogenous secretory solutes to be associated with CKD progression and all-cause mortality, independent of eGFR and albuminuria. This suggests that tubular clearance of secretory solutes provides additional information about kidney health beyond measurements of glomerular function alone.

Nonparametric Assessment of Differences Between Competing Risk Hazard Ratios: Application to Racial Differences in Pediatric Chronic Kidney Disease Progression

Associations between an exposure and multiple competing events are typically described by cause-specific hazard ratios (csHR) or subdistribution hazard ratios (sHR). However, diagnostic tools to assess differences between them have not been described. Under the proportionality assumption for both, it can be shown mathematically that the sHR and csHR must be equal, so reporting different time-constant sHR and csHR implies non-proportionality for at least one. We propose a simple, intuitive approach using the ratio of sHR/csHR to nonparametrically compare these metrics. In general, for the non-null case, there must be at least one event type for which the sHR and csHR differ, and the proposed diagnostic will be useful to identify these cases. Furthermore, once standard methods are used to estimate the csHR, multiplying it with our nonparametric estimate for the sHR/csHR ratio will yield estimates of sHR which fulfill intrinsic linkages of the subhazards that separate analysis may violate. In addition, for non-null cases, at least one must be time dependent (i.e., non-proportional), and thus our tool serves as an indirect test of the proportionality assumption. We applied this proposed diagnostic tool to data from a cohort of children with congenital kidney disease to describe racial differences in the time to first dialysis or first transplant and extend methods to include adjustment for socioeconomic factors.

Genetic polymorphism in C3 is associated with progression in chronic kidney disease (CKD) patients with IgA nephropathy but not in other causes of CKD

Objectives

The R102G variant in complement 3 (C3) results in two allotypic variants: C3 fast (C3F) and C3 slow (C3S). C3F presents at increased frequency in patients with chronic kidney disease (CKD), our aim is to explore its role in CKD progression and mortality.

Methods

Delta (Δ) eGFR for 2038 patients in the Salford Kidney Study (SKS) was calculated by linear regression; those with ≤-3ml/min/1.73m²/yr were defined as rapid progressors (RP) and those with ΔeGFR between -0.5 and +1ml/min/1.73m²/yr, labelled stable CKD patients (SP).A group of 454 volunteers was used as a control group. In addition, all biopsy-proven glomerulonephritis (GN) patients were studied regardless of their ΔeGFR. R102G was analysed by real-time PCR, and genotypic and allelic frequencies were compared between RP and SP along with the healthy control group.

Results

There were 255 SP and 259 RP in the final cohort. Median ΔeGFR was 0.07 vs. -4.7 ml/min/1.73m²/yr in SP vs. RP. C3F allele frequency was found to be significantly higher in our CKD cohort (25.7%) compared with the healthy control group (20.6%); p = 0.008.However, there was no significant difference in C3F allele frequency between the RP and SP groups. In a subgroup analysis of 37 patients with IgA nephropathy in the CKD cohort (21 RP and 16 SP), there was a significantly higher frequency of C3F in RP 40.5% vs. 9.4% in SP; p = 0.003. In the GN group, Cox regression showed an association between C3F and progression only in those with IgA nephropathy (n = 114);HR = 1.9 (95% CI 1.1–3.1; p = 0.018) for individuals heterozygous for the C3F variant, increased further for individuals homozygous for the variant, HR = 2.8 (95% CI 1.2–6.2; p = 0.014).

Conclusion

The C3 variant R102G is associated with progression of CKD in patients with IgA nephropathy.

The Risk of Stroke and Stroke Type in Patients With Atrial Fibrillation and Chronic Kidney Disease

Background:

Atrial fibrillation (AF) and chronic kidney disease (CKD) are known to increase the risk of stroke.

Objectives:

We set out to examine the risk of stroke by kidney function and albuminuria in patients with and without AF.

Design:

Retrospective cohort study.

Settings:

Ontario, Canada.

Participants:

A total of 736 666 individuals (>40 years) from 2002 to 2015.

Measurements:

New-onset AF, albumin-to-creatinine ratio (ACR), and an estimated glomerular filtration rate (eGFR).

Methods:

A total of 39 120 matched patients were examined for the risk of ischemic, hemorrhagic, or any stroke event, accounting for the competing risk of all-cause mortality. Interaction terms for combinations of ACR/eGFR and the outcome of stroke with and without AF were examined.

Results:

In a total of 4086 (5.2%) strokes (86% ischemic), the presence of AF was associated with a 2-fold higher risk for any stroke event and its subtypes of ischemic and hemorrhagic stroke. Across eGFR levels, the risk of stroke was 2-fold higher with the presence of AF except for low levels of eGFR (eGFR < 30 mL/min/1.73 m², hazard ratio [HR]: 1.38, 95% confidence interval [CI]: 0.99-1.92). Similarly across ACR levels, the risk of stroke was 2-fold higher except for high levels of albuminuria (ACR > 30 mg/g, HR: 1.61, 95% CI: 1.31-1.99). The adjusted risk of stroke with AF differed by combinations of ACR and eGFR categories (interaction P value = .04) compared with those without AF. Both stroke types were more common in patients with AF, and ischemic stroke rates differed significantly by eGFR and ACR categories.

Limitations:

Medication information was not included.

Conclusions:

Patients with CKD and AF are at a high risk of total, ischemic, and hemorrhagic strokes; the risk is highest with lower eGFR and higher ACR and differs based on eGFR and the degree of ACR.

Dose-response relationship between gamma-glutamyltransferase and the risk of atherosclerotic cardiovascular diseases in Korean adults

BACKGROUND AND AIMS

The value of gamma-glutamyltransferase (GGT) in the putative mechanisms underlying its association with cardiovascular disease is unclear. This study examined whether serum GGT value has an independent association and dose-response relationship with the risk of atherosclerotic cardiovascular disease (ASCVD).

METHODS

This observational study included 419,433 subjects from the National Health Insurance Service database. Serum GGT levels were classified into sex-specific quartiles. We used Cox proportional hazard models to examine the effect of serum GGT values on the risk of ASCVD. We quantified associations of the serum GGT quartile groups with risk of ASCVD or each subtype through multivariate sub-distribution hazard models adjusted for covariates at baseline.

RESULTS

During 4,572,993.8 person-years of follow-up for ASCVD, we documented 40,359 (9.6%) incident cases of ASCVD. The highest serum GGT group had a significant association with ASCVD in contrast to the lowest serum GGT quartile group (hazard ratio [HR] = 1.23, 95% confidence interval [CI] = 1.19-1.27). Serum GGT quartile groups 2, 3, and 4 had a significantly higher risk for incident hemorrhagic stroke than the serum GGT quartile group 1 (Q 2: HR = 0.92, 95% CI = 0.83-1.02; Q 3: HR = 1.03, 95% CI = 0.93-1.15; Q 4: HR = 1.29, 95% CI = 1.16-1.42; p for trend <0.001). For ischemic heart disease (IHD) and myocardial infarction, non-linear trends were shown according to increasing log-transformed GGT values. In the dose-response trends to assess the interaction effect of obese status, differences of trends were shown between serum GGT level and IHD or hemorrhagic stroke.

CONCLUSIONS

The serum GGT value, which is known as a factor linked to cardiovascular diseases, has a strong independent association and dose-response relationship with hemorrhagic stroke risk in contrast to that with ischemic stroke or IHD.

Competing mortality risks analysis of prediagnostic lifestyle and dietary factors in colorectal cancer survival: the Norwegian Women and Cancer Study

Background

It remains unclear whether or which prediagnostic lifestyle and dietary factors influence colorectal cancer (CRC) survival following diagnosis. This study used competing mortality risks analysis to evaluate the association between these factors and CRC survival.

Methods

A total of 96 889 cancer-free participants of the Norwegian Women and Cancer Study completed the study’s baseline questionnaire on lifestyle and dietary factors between 1996 and 2004. Of the 1861 women who subsequently developed CRC, 550 had CRC as the cause of death, while 110 had a non-CRC cause of death. We used multiple imputation to handle missing data. We performed multivariable competing mortality risks analyses to determine the associations between prediagnostic lifestyle and dietary factors and CRC survival. Cause-specific HRs were estimated by Cox regression and subdistribution HRs were estimated by the Fine-Gray regression with corresponding 95% CIs.

Results

Following multivariable adjustment, a prediagnostic vitamin D intake of >10 μg/day compared with ≤10 μg/day was associated with better CRC survival (HR=0.75, 95% CI 0.61 to 0.92). Other prediagnostic lifestyle and dietary factors showed no association with CRC survival. The corresponding results obtained from cause-specific Cox and Fine-Gray regressions were similar.

Conclusion

Our study shows that prediagnostic vitamin D intake could improve CRC survival.

Serum Calcification Propensity and Clinical Events in CKD

BACKGROUND AND OBJECTIVES

Patients with CKD are at high risk for cardiovascular disease, ESKD, and mortality. Vascular calcification is one pathway through which cardiovascular disease risks are increased. We hypothesized that a novel measure of serum calcification propensity is associated with cardiovascular disease events, ESKD, and all-cause mortality among patients with CKD stages 2-4.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Among 3404 participants from the prospective, longitudinal Chronic Renal Insufficiency Cohort Study, we quantified calcification propensity as the transformation time (T₅₀) from primary to secondary calciprotein particles, with lower T₅₀ corresponding to higher calcification propensity. We used multivariable-adjusted Cox proportional hazards regression models to assess the associations of T₅₀ with risks of adjudicated atherosclerotic cardiovascular disease events (myocardial infarction, stroke, and peripheral artery disease), adjudicated heart failure, ESKD, and mortality.

RESULTS

The mean T₅₀ was 313 (SD 79) minutes. Over an average 7.1 (SD 3.1) years of follow-up, we observed 571 atherosclerotic cardiovascular disease events, 633 heart failure events, 887 ESKD events, and 924 deaths. With adjustment for traditional cardiovascular disease risk factors, lower T₅₀ was significantly associated with higher risk of atherosclerotic cardiovascular disease (hazard ratio [HR] per SD lower T₅₀, 1.14; 95% confidence interval [95% CI], 1.05 to 1.25), ESKD within 3 years from baseline (HR per SD lower T₅₀, 1.68; 95% CI, 1.52 to 1.86), and all-cause mortality (HR per SD lower T₅₀, 1.16; 95% CI, 1.09 to 1.24), but not heart failure (HR per SD lower T₅₀, 1.06; 95% CI, 0.97 to 1.15). After adjustment for eGFR and 24-hour urinary protein, T₅₀ was not associated with risks of atherosclerotic cardiovascular disease, ESKD, and mortality.

CONCLUSIONS

Among patients with CKD stages 2-4, higher serum calcification propensity is associated with atherosclerotic cardiovascular disease events, ESKD, and all-cause mortality, but this association was not independent of kidney function.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2019_10_28_CJN04710419.mp3.

Examining internal migration effects on short versus long interbirth intervals in Cotonou, Benin Republic

Background

The literature on migration-fertility relationship uses various measures of fertility, such as fertility rates, actual fertility and family size preferences. This study introduces a different measure—interbirth intervals over women’s reproductive years—to examine how internal migration is associated with short interbirth intervals (less than 24 months) and long interbirth intervals (greater than 60 months) in Cotonou, the largest city of Benin Republic.

Methods

The paper uses primary data on 2852 live births to 1659 women aged 15–49 years from the 2018 Fertility and Migration Survey in Cotonou. Competing-risks models were fitted for the analysis.

Results

Nineteen percent of live births were of short interbirth intervals and 16% were of long interbirth intervals. The prevalence of short interbirth intervals was higher among migrants who spent less than 5 years in Cotonou (29%) than among non-migrants (19%) and earlier migrants (18%). Non-migrants had the highest proportion of long interbirth intervals (19%). Within the first 5 years following the migration to Cotonou, migrants had higher subhazard ratio (SHR) of short interbirth intervals (SHR: 1.71, 95% CI: 1.33–2.21) and lower SHR of long interbirth intervals (SHR: 0.64, 95% CI: 0.47–0.87) than non-migrants. This association holds after controlling for socioeconomic characteristics—but with a slightly reduced gap between migrants who spent less than 5 years in Cotonou and non-migrants. Afterwards and irrespective of women’s socioeconomic backgrounds, migrants who spent 5 or more years in Cotonou and non-migrants had similar risks of short and long interbirth intervals. Finally, from 5 years of stay in Cotonou, migrants for reasons other than school or job were less likely to experience short interbirth intervals (SHR: 0.65, 95% CI: 0.46–0.98 for migrants who spent 5–10 years in Cotonou, and SHR: 0.74, 95% CI: 0.54–1.02 for migrants who spent more than 10 years in Cotonou) than non-migrants.

Conclusion

Family planning programmes should mainly target migrants in the early years after their arrival in Cotonou. Moreover, non-migrants need to be sensitised on the adverse health outcomes of long interbirth intervals.

Neuropeptide Y and chronic kidney disease progression: a cohort study

Background

Neuropeptide Y (NPY) is a sympathetic neurotransmitter that has been implicated in various disorders including obesity, gastrointestinal and cardiovascular diseases.

Methods

We investigated the relationship between circulating NPY and the progression of the glomerular filtration rate (GFR) and proteinuria and the risk for a combined renal endpoint (>30% GFR loss, dialysis/transplantation) in two European chronic kidney disease (CKD) cohorts including follow-up of 753 and 576 patients for 36 and 57 months, respectively.

Results

Average plasma NPY was 104 ± 32 pmol/L in the first CKD cohort and 119 ± 41 pmol/L in the second one. In separate analyses of the two cohorts, NPY associated with the progression of the estimated GFR (eGFR) and proteinuria over time in both unadjusted and adjusted {eGFR: -3.60 mL/min/1.73 m2 [95% confidence interval (CI): -4.46 to - 2.74] P < 0.001 and -0.83 mL/min/1.73 m2 (-1.41 to - 0.25, P = 0.005); proteinuria: 0.18 g/24 h (0.11-0.25) P < 0.001 and 0.07 g/24 h (0.005-0.14) P = 0.033} analyses by the mixed linear model. Accordingly, in a combined analysis of the two cohorts accounting for the competitive risk of death (Fine and Gray model), NPY predicted (P = 0.005) the renal endpoint [sub-distribution hazard ratio (SHR): 1.09; 95% CI: 1.03-1.16; P = 0.005] and the SHR in the first cohort (1.14, 95% CI: 1.04-1.25) did not differ (P = 0.25) from that in the second cohort (1.06, 95% CI: 0.98-1.15).

Conclusions

NPY associates with proteinuria and faster CKD progression as well as with a higher risk of kidney failure. These findings suggest that the sympathetic system and/or properties intrinsic to the NPY molecule may play a role in CKD progression.

Population-based study evaluating and predicting the probability of death resulting from thyroid cancer among patients with papillary thyroid microcarcinoma

BACKGROUND

Papillary thyroid microcarcinoma (PTMC) is an indolent carcinoma. The cumulative incidence of death from patients with PTMC and the nomogram built based on the competing risks model have not been described.

METHODS

Patients diagnosed with PTMC were selected from the Surveillance, Epidemiology, and End Results (SEER) program (1983-2015). Cumulative incidence function was utilized to calculate the likelihood of death resulting from thyroid cancer. Gray's test was conducted to examine the difference in the cumulative incidence of death between groups. A proportional subdistribution hazard model was constructed and we further built a nomogram to quantify the likelihood of death using the model. A 10-fold cross-validation procedure was adopted to validate the model.

RESULTS

A total of 46 662 patients diagnosed with PTMC were included. The median follow-up time was 81 months (range, 1 to 407 months). The 5-year, 10-year, and 20-year probabilities of death from thyroid carcinoma were 0.3%, 0.6%, and 1.4%, respectively. The age at diagnosis, sex, tumor extension, and lymph node involvement were related to the cumulative incidence of death. A proportional subdistribution hazard model was developed. The performance of the model was good. A nomogram was built based on the model to predict the likelihood of death in patients with PTMC.

CONCLUSION

The survival rate of patients with PTMC is excellent. The nomogram constructed based on the well-performed competing risks model is helpful for both patients and clinicians.

Mortality Associated With Development of Squamous Cell Cancer in Patients With Inflammatory Bowel Diseases Receiving Treatment With Thiopurines

BACKGROUND & AIMS

Treatment with thiopurines is associated with an increased risk of squamous cell carcinoma of the skin (SCC) in patients with inflammatory bowel diseases (IBD). We studied outcomes of patients with IBD who developed SCC while receiving thiopurine therapy.

METHODS

We conducted a retrospective cohort study of 54,919 patients with IBD followed in the nationwide Veterans Affairs Healthcare System from January 1, 2000, through May 23, 2018. From this cohort, we created a sub-cohort of patients with an incident diagnosis of SCC, confirmed by review of patients' medical records; we identified those who had received treatment with thiopurines (exposed group) vs those treated with mesalamine and no prior exposure to thiopurines or tumor necrosis factor antagonists (unexposed group). The primary outcome was death associated with SCC (SCC mortality). We collected data on baseline demographic features, exposure to ultraviolet light, Charlson comorbidity index, smoking status, and environmental exposures. Follow up began at the time of incident SCC diagnosis and ended at death or last recorded date in the health system. Cause-specific hazard models were used to estimate the adjusted and unadjusted hazard ratio (HRs), with 95% CIs, for SCC mortality.

RESULTS

We identified 467 patients with incident SCC and included 449 patients (161 exposed and 288 unexposed) in our final analysis. Eleven patients from complications of SCC (8 in the exposed group and 3 in the unexposed group). The estimated 5- and 10-year cumulative mortality values were 2.9% and 2.9% in the exposed group and 0.4% and 0.9% in the unexposed group, respectively. The unadjusted and adjusted cause-specific HRs for SCC mortality associated with exposure were 7.0 (95% CI, 1.8-28.0; P = .006) and 8.0 (95% CI, 2.0-32.8; P = .004), respectively.

CONCLUSIONS

Although the cause-specific mortality is relatively low, patients with IBD exposed to thiopurines who develop SCC have an increased risk of SCC-associated death compared to patients exposed to only mesalamine.

The Association of Kidney Function and Albuminuria With the Risk and Outcomes of Syncope: A Population-Based Cohort Study

BACKGROUND

The risks and subsequent outcomes of syncope among seniors with chronic kidney disease (CKD) are unclear.

METHODS

We conducted a population-based retrospective cohort study of 272,146 patients ≥ 66 years old, in Ontario, Canada, from April 1, 2006, to March 31, 2016. Using administrative health care databases, we examined the association of estimated glomerular filtration rate (eGFR) and urine albumin to creatinine ratio (ACR) with incident syncope and the association of incident syncope with the composite outcome of myocardial infarction, stroke, and death by levels of eGFR/ACR, using adjusted Cox proportional hazards models.

RESULTS

A total of 15,074 incident syncopal events occurred during the study period. The adjusted risk for syncope was higher with a lower eGFR and higher ACR in a stepwise manner (eGFR 60 to < 90: HR 1.17 [1.09-1.26] vs eGFR < 30: HR 1.67 (1.50-1.87) with eGFR ≥ 90 referent; ACR > 30: HR 1.15 [1.07-1.24] with ACR < 3 referent). Among the 12,710 patients with a first syncope event and 1 year of follow-up, the adjusted risk for the composite outcome was higher with a lower eGFR and higher ACR in a stepwise manner (eGFR 60 to < 90: HR 1.05 [0.90-1.22] vs eGFR < 30: HR 1.62 [1.34-1.96] with eGFR ≥ 90 referent; ACR > 30: HR 1.77 [1.60-1.96], ACR < 3 referent).

CONCLUSIONS

A lower eGFR and higher ACR are associated with a higher risk of a hospital encounter for syncope and of related complications among persons of advanced age.

Estimate of hepatocellular carcinoma incidence in patients with alcoholic cirrhosis

BACKGROUND & AIMS

More than 90% of cases of hepatocellular carcinoma (HCC) occur in patients with cirrhosis, of which alcohol is a major cause. The CIRRAL cohort aimed to assess the burden of complications in patients with alcoholic cirrhosis, particularly the occurrence of HCC.

METHODS

Patients with biopsy-proven compensated alcoholic cirrhosis were included then prospectively followed. The main endpoint was the incidence of HCC. Secondary outcomes were incidence of hepatic focal lesions, overall survival (OS), liver-related mortality and event-free survival (EFS).

RESULTS

From October 2010 to April 2016, 652 patients were included in 22 French and Belgian centers. During follow-up (median 29 months), HCC was diagnosed in 43 patients. With the limitation derived from the uncertainty of consecutive patients' inclusion and from a sizable proportion of dropouts (153/652), the incidence of HCC was 2.9 per 100 patient-years, and one- and two-year cumulative incidences of 1.8% and 5.2%, respectively. Although HCC fulfilled the Milan criteria in 33 cases (77%), only 24 patients (56%) underwent curative treatment. An explorative prognostic analysis showed that age, male gender, baseline alpha-fetoprotein, bilirubin and prothrombin were significantly associated with the risk of HCC occurrence. Among 73 deaths, 61 had a recorded cause and 27 were directly attributable to liver disease. At two years, OS, EFS and cumulative incidences of liver-related deaths were 93% (95% CI 90.5-95.4), 80.3% (95% CI 76.9-83.9), and 3.2% (95% CI 1.6-4.8) respectively.

CONCLUSION

This large prospective cohort incompletely representative of the whole population with alcoholic cirrhosis showed: a) an annual incidence of HCC of up to 2.9 per 100 patient-years, suggesting that surveillance might be cost effective in these patients; b) a high proportion of HCC detected within the Milan criteria, but only one-half of detected HCC cases were referred for curative treatments; c) a two-year mortality rate of up to 7%.

LAY SUMMARY

Cirrhosis is a risk factor for primary liver cancer, leading to recommendations for periodic screening. However, for alcohol-related liver disease the rational of periodic screening for hepatocellular carcinoma (HCC) is controversial, as registry and databased studies have suggested a low incidence of HCC in these patients and highly competitive mortality rates. In this study, a large cohort of patients with biopsy-proven alcoholic cirrhosis prospectively screened for HCC demonstrated a high annual incidence of HCC (2.9%) and a high percentage of small cancers theoretically eligible for curative treatment. This suggests that patients with liver disease related to alcohol should not be ruled out of screening.

Age Modifies the Association of Dietary Protein Intake with All-Cause Mortality in Patients with Chronic Kidney Disease

Whether the effect of a low-protein diet on progression to end-stage renal disease (ESRD) and mortality risk differs between young and elderly adults with chronic kidney disease (CKD) is unclear. We conducted a retrospective CKD cohort study to investigate the association between protein intake and mortality or renal outcomes and whether age affects this association. The cohort comprised 352 patients with stage G3-5 CKD who had been followed up for a median 4.2 years, had undergone educational hospitalization, and for whom baseline protein intake was estimated from 24-h urine samples. We classified the patients into a very low protein intake (VLPI) group (<0.6 g/kg ideal body weight/day), a low protein intake (LPI) group (0.6⁻0.8 g), and a moderate protein intake (MPI) group (>0.8 g). Compared with the LPI group, the MPI group had a significantly lower risk of all-cause mortality (hazard ratio: 0.29; 95% confidence interval: 0.07 to 0.94) but a similar risk of ESRD, although relatively high protein intake was related to a faster decline in the estimated glomerular filtration rate. When examined per age group, these results were observed only among the elderly patients, suggesting that the association between baseline dietary protein intake and all-cause mortality in patients with CKD is age-dependent.

Albuminuria, Reduced Kidney Function, and the Risk of ST - and non-ST-segment-elevation myocardial infarction

Background Chronic kidney disease is a recognized independent risk factor for cardiovascular disease, but whether the risks of ST-segment-elevation myocardial infarction ( STEMI ) and non-ST-segment-elevation myocardial infarction ( NSTEMI ) differ in the chronic kidney disease population is unknown. Methods and Results Using administrative data from Ontario, Canada, we examined patients ≥66 years of age with an outpatient estimated glomerular filtration rate ( eGFR ) and albuminuria measure for incident myocardial infarction from 2002 to 2015. Adjusted Fine and Gray subdistribution hazard models accounting for the competing risk of death were used. In 248 438 patients with 1.2 million person-years of follow-up, STEMI , NSTEMI , and death occurred in 1436 (0.58%), 4431 (1.78%), and 30 015 (12.08%) patients, respectively. The highest level of albumin-to-creatinine ratio (>30 mg/mmol) was associated with a 2-fold higher adjusted risk of both STEMI and NSTEMI among patients with eGFR ≥60 mL/(min·1.73 m2) compared to albumin-to-creatinine ratio <3 mg/mmol. The lowest level of eGFR (<30 mL/[min·1.73 m2]) was not associated with higher STEMI risk but with a 4-fold higher risk of NSTEMI compared to those with eGFR ≥60 mL/(min·1.73 m2). The lowest eGFR (<30 mL/[min·1.73 m2]) and highest albumin-to-creatinine ratio (>30 mg/mmol) were associated with a greater than 4-fold higher risk of both STEMI and NSTEMI (subdistribution hazard models [95% confidence interval] 4.53 [3.30-6.21] and 4.42 [3.67-5.32], respectively) compared to albumin-to-creatinine ratio <3 mg/mmol and eGFR ≥60 mL/(min·1.73 m2). Conclusions Elevations in albuminuria are associated with a higher risk of both NSTEMI and STEMI , regardless of kidney function, whereas reduced kidney function alone is associated with a higher NSTEMI risk.

Blood urea nitrogen and risk of insulin use among people with diabetes

Laboratory evidence suggests that urea suppresses insulin secretion and sensitivity. Emerging epidemiologic evidence suggests that higher levels of urea are associated with increased risk of incident diabetes mellitus. However, whether elevated levels of blood urea nitrogen are associated with increased risk of insulin use among people with diabetes is unknown. We used the Department of Veterans Affairs databases to assemble a cohort of 197,994 incident users of non-insulin hypoglycaemic agents with an estimated glomerular filtration rate > 60 mL/min per 1.73 m² and followed them for a median of 4.93 years. Spline analyses suggested that the relationship between blood urea nitrogen and the risk of insulin use was neutral below blood urea nitrogen level of 25 mg/dL and increased exponentially with blood urea nitrogen levels above 25 mg/dL. In survival models, compared to those with blood urea nitrogen ⩽ 25 mg/dL, those with blood urea nitrogen > 25 mg/dL had an increased risk of insulin use (hazard ratio = 1.40; confidence interval = 1.30-1.50). The risk of insulin use was increased in models which accounted for haemoglobin A1c at time zero (hazard ratio = 1.39; confidence interval = 1.28-1.50) and as a time-varying variable (hazard ratio = 1.38; confidence interval = 1.28-1.50). Two-step residual estimation analyses showed that, independent of the impact of estimated glomerular filtration rate, every 10-mg/dL increase in blood urea nitrogen concentration was associated with increased risk of insulin use (hazard ratio = 1.16; confidence interval = 1.12-1.20). Our results suggest that, among people with diabetes, higher levels of blood urea nitrogen are associated with an increased risk of insulin use.

Coffee Consumption and Incident Kidney Disease: Results From the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

Moderate coffee consumption has been suggested to be associated with lower risk for chronic conditions such as diabetes, a major precursor to chronic kidney disease (CKD). However, the association between coffee and CKD has not been fully established. STUDY DESIGN: Prospective cohort study.

SETTING & PARTICIPANTS

14,209 participants aged 45 to 64 years from the Atherosclerosis Risk in Communities (ARIC) Study.

PREDICTORS

Coffee consumption (cups per day) was assessed at visits 1 (1987-1989) and 3 (1993-1995) using food frequency questionnaires.

OUTCOMES

Incident CKD defined as estimated glomerular filtration rate < 60mL/min/1.73m2 accompanied by ≥25% estimated glomerular filtration rate decline, CKD-related hospitalization or death, or end-stage renal disease.

RESULTS

There were 3,845 cases of incident CKD over a median of 24 years of follow-up. Men, whites, current smokers, and participants without comorbid conditions were more likely to consume higher amounts of coffee per day. After adjustment for demographic, clinical, and dietary factors, higher categories of coffee consumption were associated with lower risk for incident CKD compared with those who never consumed coffee (HR for <1 cup per day, 0.90 [95% CI, 0.82-0.99]; 1-<2 cups per day, 0.90 [95% CI, 0.82-0.99]; 2-<3 cups per day, 0.87 [95% CI, 0.77-0.97]; and ≥3 cups per day, 0.84 [95% CI, 0.75-0.94]). In continuous analysis, for each additional cup of coffee consumed per day, risk for incident CKD was lower by 3% (HR, 0.97; 95% CI, 0.95-0.99; P<0.001).

LIMITATIONS

Self-reported coffee consumption and observational design.

CONCLUSIONS

Participants who drank higher amounts of coffee had lower risk for incident CKD after adjusting for covariates. Coffee consumers may not be at adverse risk for kidney disease.

Standard and competing risk analysis of the effect of albuminuria on cardiovascular and cancer mortality in patients with type 2 diabetes mellitus

BACKGROUND

Competing risks occur when populations may experience outcomes that either preclude or alter the probability of experiencing the main study outcome(s). Many standard survival analysis methods do not account for competing risks. We used mortality risk in people with diabetes with and without albuminuria as a case study to investigate the impact of competing risks on measures of absolute and relative risk.

METHODS

A population with type 2 diabetes was identified in Clinical Practice Research Datalink as part of a historical cohort study. Patients were followed for up to 9 years. To quantify differences in absolute risk estimates of cardiovascular and cancer, mortality standard (Kaplan-Meier) estimates were compared to competing-risks-adjusted (cumulative incidence competing risk) estimates. To quantify differences in measures of association, regression coefficients for the effect of albuminuria on the relative hazard of each outcome were compared between standard cause-specific hazard (CSH) models (Cox proportional hazards regression) and two competing risk models: the unstratified Lunn-McNeil model, which estimates CSH, and the Fine-Gray model, which estimates subdistribution hazard (SDH).

RESULTS

In patients with normoalbuminuria, standard and competing-risks-adjusted estimates for cardiovascular mortality were 11.1% (95% confidence interval (CI) 10.8-11.5%) and 10.2% (95% CI 9.9-10.5%), respectively. For cancer mortality, these figures were 8.0% (95% CI 7.7-8.3%) and 7.2% (95% CI 6.9-7.5%). In patients with albuminuria, standard and competing-risks-adjusted estimates for cardiovascular mortality were 21.8% (95% CI 20.9-22.7%) and 18.5% (95% CI 17.8-19.3%), respectively. For cancer mortality, these figures were 10.7% (95% CI 10.0-11.5%) and 8.6% (8.1-9.2%). For the effect of albuminuria on cardiovascular mortality, regression coefficient values from multivariable standard CSH, competing risks CSH, and competing risks SDH models were 0.557 (95% CI 0.491-0.623), 0.561 (95% CI 0.494-0.628), and 0.456 (95% CI 0.389-0.523), respectively. For the effect of albuminuria on cancer mortality, these values were 0.237 (95% CI 0.148-0.326), 0.244 (95% CI 0.154-0.333), and 0.102 (95% CI 0.012-0.192), respectively.

CONCLUSIONS

Studies of absolute risk should use methods that adjust for competing risks to avoid over-stating risk, such as the CICR estimator. Studies of relative risk should consider carefully which measure of association is most appropriate for the research question.

Soluble Urokinase Plasminogen Activator Receptor (suPAR) and All-Cause and Cardiovascular Mortality in Diverse Hemodialysis Patients

Introduction

The soluble receptor of urokinase plasminogen activator (suPAR) is an innate immunity/inflammation biomarker predicting cardiovascular (CV) and non-CV events in various conditions, including type 2 diabetic patients on dialysis. However, the relationship between suPAR and clinical outcomes in the hemodialysis population at large has not been tested.

Methods

We measured plasma suPAR levels (R&D enzyme-linked immunosorbent assay [ELISA]) in 1038 hemodialysis patients with a follow-up of 2.9 years (interquartile range = 1.7−4.2) who were enrolled in the PROGREDIRE study, a cohort study involving 35 dialysis units in 2 regions in Southern Italy.

Results

suPAR was strongly (P < 0.001) and independently related to female gender (β = −0.160), age (β = 0.216), dialysis vintage (β = 0.264), CV comorbidities (β = 0.105), alkaline phosphatase (β = 0.136), albumin (β = −0.147), and body mass index (BMI; β = 0.174) (all P < 0.006). In fully adjusted analyses, suPAR tertiles predicted the risk of all-cause mortality (third tertile vs. first tertile hazard ratio (HR) = 1.91, 95% confidence interval (CI) = 1.47 – 2.48, P < 0.001), CV mortality (HR = 1.47, 95% CI = 1.03–2.09, P = 0.03), and non-CV mortality (HR = 1.94, 95% CI = 1.28–2.93, P = 0.002); these relationships were not modified by diabetes or other risk factors. suPAR added only modest prognostic risk discrimination and reclassification power for these outcomes to parsimonious models based on simple clinical variables.

Conclusion

In conclusion, suPAR robustly predicted all-cause and both CV and non-CV mortality in a large unselected hemodialysis population. Intervention studies are needed to definitively test the hypothesis that suPAR is causally implicated in clinical outcomes in this population.

Reduced Levels of Anti-Ageing Hormone Klotho Predict Renal Function Decline in Type 2 Diabetes

CONTEXT AND OBJECTIVE

Soluble Klotho (sKlotho) is a circulating hormone with cardiovascular-renal protective effects. Whether sKlotho predicts estimated glomerular filtration rate (eGFR) decline in patients with type 2 diabetes mellitus (T2DM) with relatively preserved renal function is unknown.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

Single-center observational follow-up study of 101 patients with T2DM and eGFR >45 mL/min [91% on renin angiotensin system (RAS) blockade] followed for a median of 9 years (range, 2 to 13 years).

MAIN OUTCOME

Primary outcome was a >50% decline in eGFR. sKlotho, serum phosphorus, serum calcium, and fibroblast growth factor-23 levels were measured from stored samples collected at baseline. Patients were followed up with standardized clinical and biochemical measurements.

RESULTS

Patients with residual microalbuminuria (MA) despite RAS blockade (n = 53) had significantly lower levels of sKlotho [median, 184.7 pg/mL; interquartile range (IQR), 130.5 to 271.8 pg/mL) compared with patients without MA (n = 39; median, 235.2 pg/mL; IQR, 172.0 to 289.4 pg/mL; P = 0.03). Of the cohort, 21% reached the primary outcome. In a competing risk analysis, a 10% higher sKlotho level reduced the incidence of the primary outcome by 12% (hazard ratio, 0.27; 95% confidence interval, 0.15 to 0.52; P < 0.001] independent of traditional risk factors. Patients with sKlotho below the median of 204.4 pg/mL had nearly a fourfold higher cumulative incidence of the primary outcome compared with those above the median (24% vs 6.2%; P = 0.01).

CONCLUSIONS

In patients with T2DM with relatively preserved eGFR, reduced levels of sKlotho predict renal function decline independent of traditional risk markers. sKlotho is a biomarker of renal dysfunction and a potential treatment target for renoprotection in T2DM.

Association of Kidney Disease Quality of Life (KDQOL-36) with mortality and hospitalization in older adults receiving hemodialysis

Background

For older adults receiving dialysis, health-related quality of life is not often considered in prognostication of death or future hospitalizations. To determine if routine health-related quality of life measures may be useful for prognostication, the objective of this study is to determine the extent of association of Kidney Disease Quality of Life (KDQOL-36) subscales with adverse outcomes in older adults receiving dialysis.

Methods

This is a longitudinal study of 3500 adults aged ≥75 years receiving dialysis in the United States in 2012 and 2013. We used Cox and Fine and Gray models to evaluate the association of KDQOL-36 subscales with risk of death and hospitalization. We adjusted for sociodemographic variables, hemodialysis access type, laboratory values, and Charlson index.

Results

Three thousand one hundred thirty-two hemodialysis patients completed the KDQOL-36. From KDQOL-36 completion date in 2012, 880 (28.1%) died and 2023 (64.6%) had at least one hospitalization over a median follow-up of 512 and 203 days, respectively. Cohort members with a SF-12 physical component summary (PCS) in the lowest quintile had an increased adjusted risk of death [hazard ratio (HR), 1.55, 95% confidence interval (CI) 1.19–2.03] and hospitalization (HR, 1.29, 95% CI 1.09–1.54) compared with those with scores in the highest quintile. Cohort members with a SF-12 mental component summary in the lowest quintile had an increased risk of hospitalization (HR, 1.39, 95% CI 1.17–1.65) compared with those in the highest quintile. In adjusted analyses, there was no association between the symptoms of kidney disease, effects of kidney disease, and burden of kidney disease subscales with time to death or first hospitalization. Competing risk models showed similar HRs.

Conclusions

Among the KDQOL-36 subscales, the SF-12 PCS demonstrates the strongest association with both death and future hospitalizations in older adults receiving hemodialysis Further research is needed to assess the value this subscale may add to prognostication.

Electronic supplementary material

The online version of this article (10.1186/s12882-017-0801-5) contains supplementary material, which is available to authorized users.

Higher blood urea nitrogen is associated with increased risk of incident diabetes mellitus

Experimental evidence suggests that higher levels of urea may increase insulin resistance and suppress insulin secretion. However, whether higher levels of blood urea nitrogen (BUN) are associated with increased risk of incident diabetes mellitus in humans is not known. To study this, we built a national cohort of 1,337,452 United States Veterans without diabetes to characterize the association of BUN and risk of incident diabetes. Over a median follow-up of 4.93 years, there were 172,913 cases of incident diabetes. In joint risk models of estimated glomerular filtration rate (eGFR) and BUN. there was no association between eGFR and the risk of incident diabetes in those with a BUN of 25 mg/dl or less. However, the risk was significantly increased in those with a BUN over 25 mg/dl at all eGFR levels, even in those with an eGFR of 60 ml/min/1.73m² or more (hazard ratio 1.27; confidence interval 1.24-1.31). The risk of incident diabetes was highest in those with BUN over 25 mg/dL and an eGFR under 15 ml/min/1.73m² (1.68; 1.51-1.87). Spline analyses of the relationship between BUN and risk of incident diabetes showed that risk was progressively higher as BUN increased. In models where eGFR was included as a continuous covariate, compared to a BUN of 25 mg/dl or less, a BUN over 25 mg/dl was associated with increased risk of incident diabetes (1.23; 1.21-1.25). Every 10 ml/min/1.73m² decrease in eGFR was not associated with risk of incident diabetes (1.00; 1.00-1.01). Two-stage residual inclusion analyses showed that, independent of the impact of eGFR, every 10 mg/dL increase in BUN concentration was associated with increased risk of incident diabetes (1.15; 1.14-1.16). Thus, higher levels of BUN are associated with increased risk of incident diabetes mellitus.