Predicting progression of IgA nephropathy: new clinical progression risk score

External Validation of the International Prognosis Prediction Model of IgA Nephropathy

BACKGROUND

The International IgA Nephropathy (IgAN) Network developed and validated two prognostic prediction models for IgAN, one incorporating a race parameter. These models could anticipate the risk of a 50% reduction in estimated glomerular filtration rate (eGFR) or progression to end-stage renal disease (ESRD) subsequent to an IgAN diagnosis via renal biopsy. This investigation aimed to validate the International IgA Nephropathy Prediction Tool (IIgANPT) within a contemporary Chinese cohort.

METHODS

Within this study,185 patients diagnosed with IgAN via renal biopsy at the Center for Kidney Disease, Second Affiliated Hospital of Nanjing Medical University, between January 2012 and December 2021, were encompassed. Each patient's risk of progression was assessed utilizing the IIgANPT formula. The primary outcome, a 50% decline in eGFR or progression to ESRD, was examined. Two predictive models, one inclusive and the other exclusive of a race parameter, underwent evaluation via receiver-operating characteristic (ROC) curves, subgroup survival analyses, calibration plots, and decision curve analyses.

RESULTS

The median follow-up duration within our cohort spanned 5.1 years, during which 18 patients encountered the primary outcome. The subgroup survival curves exhibited distinct separations, and the comparison of clinical and histological characteristics among the risk subgroups revealed significant differences. Both models demonstrated outstanding discrimination, evidenced by the areas under the ROC curve at five years: 0.882 and 0.878. Whether incorporating the race parameter or not, both prediction models exhibited acceptable calibration. Decision curve analysis affirmed the favorable clinical utility of both models.

CONCLUSIONS

Both prognostic risk evaluation models for IgAN exhibited remarkable discrimination, sound calibration, and acceptable clinical utility.

The humanistic burden of immunoglobulin A nephropathy on patients and care-partners in the United States

PURPOSE

This cross-sectional survey study quantified the humanistic burden of immunoglobulin A nephropathy (IgAN), in terms of physical and mental health-related quality of life (HRQoL) and work productivity, among adults with primary IgAN and their care-partners.

METHODS

HRQoL was assessed (01/31/22 - 05/31/23) with validated tools including the KDQoL-36 (with SF-12), GAD-7 (anxiety), PHQ-9 (depression), and WPAI: SHP (work productivity). Participant characteristics and total/domain scores were summarized; selected outcomes were compared to an external, kidney disease-free cohort.

RESULTS

117 adults with IgAN and their care-partner pairs, and one adult without a care-partner, were included. The mean ages of patients and care-partners were 38.0 (SD: 8.6) and 40.2 (11.8) years, respectively; 55.9% and 43.6% were female. Mean physical and mental SF-12 scores for patients were 46.7 (SD: 8.0) and 41.9 (9.2), respectively, and 50.7 (7.3) and 43.7 (10.24) for care-partners. Both SF-12 components for patients, and the mental component for care-givers, were significantly worse compared to the US general population. Among patients, 27.1% had moderate/severe anxiety and 49.2% reported at least moderate depression. Compared to external controls, patients experienced significantly higher severity of anxiety (6.6 vs. 5.4) and depression (8.1 vs. 6.6; both p < 0.0001). Among care-partners, 13.7% experienced moderate anxiety and 37.8% experienced moderate/moderately-severe depression. Among employed individuals, both groups reported IgAN-related absenteeism (8.8-9.4%), presenteeism (25.1-25.9%), and overall work impairment (30.4-30.5%).

CONCLUSION

US adults with IgAN and their care partners experience impairments to mental and physical HRQoL and heightened levels of depression and anxiety, underscoring the need for effective IgAN therapies and care-partner support.

Representation of multimorbidity and frailty in the development and validation of kidney failure prognostic prediction models: a systematic review

BACKGROUND

Prognostic models that identify individuals with chronic kidney disease (CKD) at greatest risk of developing kidney failure help clinicians to make decisions and deliver precision medicine. It is recognised that people with CKD usually have multiple long-term health conditions (multimorbidity) and often experience frailty. We undertook a systematic review to evaluate the representation and consideration of multimorbidity and frailty within CKD cohorts used to develop and/or validate prognostic models assessing the risk of kidney failure.

METHODS

We identified studies that described derivation, validation or update of kidney failure prognostic models in MEDLINE, CINAHL Plus and the Cochrane Library-CENTRAL. The primary outcome was representation of multimorbidity or frailty. The secondary outcome was predictive accuracy of identified models in relation to presence of multimorbidity or frailty.

RESULTS

Ninety-seven studies reporting 121 different kidney failure prognostic models were identified. Two studies reported prevalence of multimorbidity and a single study reported prevalence of frailty. The rates of specific comorbidities were reported in a greater proportion of studies: 67.0% reported baseline data on diabetes, 54.6% reported hypertension and 39.2% reported cardiovascular disease. No studies included frailty in model development, and only one study considered multimorbidity as a predictor variable. No studies assessed model performance in populations in relation to multimorbidity. A single study assessed associations between frailty and the risks of kidney failure and death.

CONCLUSIONS

There is a paucity of kidney failure risk prediction models that consider the impact of multimorbidity and/or frailty, resulting in a lack of clear evidence-based practice for multimorbid or frail individuals. These knowledge gaps should be explored to help clinicians know whether these models can be used for CKD patients who experience multimorbidity and/or frailty.

SYSTEMATIC REVIEW REGISTRATION

This review has been registered on PROSPERO (CRD42022347295).

Serum soluble interleukin-2 receptor alpha may predict tubulointerstitial inflammatory cell infiltration and short-term disease progression in immunoglobin A nephropathy

This study aims to explore the relationship between serum soluble interleukin-2 receptor alpha (sIL-2Rα) levels and histologic features in immunoglobin A nephropathy (IgAN), and evaluate its predicting values on disease progression and remission status. IgAN patients were included retrospectively. Lee classification, Oxford classification and histological scoring were evaluated. Patients' estimated filtration rate (eGFR) and proteinuria remission status were collected during 6-month follow-up. Logistic regression was used to determine the risk factors and predicting value. Receiver operating characteristic (ROC) curve were used to determine the predicting value for outcome. One hundred seventy-two subjects were included in this study. Individuals in moderate-to-severe tubulointerstitial inflammatory cell infiltration group manifested with significantly elevated serum sIL-2Rα levels than those in non-to-mild group. Serum sIL-2Rα levels were positively correlated with infiltration scores. Serum sIL-2Rα was an independent risk factor for moderate-to-severe inflammatory cell infiltration [sIL-2Rα: OR 1.29 (1.015-1.640, p = 0.038)]. ROC curve analysis regarding predictive value for moderate-to-severe inflammatory cell infiltration of sIL-2Rα suggested area under curve was 0.859 (0.801-0.918, p = 0.000) when sIL-2Rα combined with eGFR < 60 mL/(min·1.73 m2), 24-h proteinuria excretion > 1.0 g, and hemoglobin. It showed good sensitivity (71.6%) and specificity (87.6%). Additionally, sIL-2Rα levels at kidney biopsy were strong predictive factor for kidney function loss 6 months after kidney biopsy [OR 4.161 (1.013-17.088, p = 0.048)]. High serum sIL-2Rα was significantly associated with serious inflammatory cell infiltration in IgAN, and it showed strong predictive value for disease prognosis. Serum sIL-2Rα could be a useful noninvasive biomarker to evaluate the extent of histological injury and disease prognosis in IgAN.

Machine learning-based diagnosis and prognosis of IgAN: A systematic review and meta-analysis

Purpose

Plenty of studies have explored the diagnosis and prognosis of IgA nephropathy (IgAN) based on machine learning (ML), but the accuracy lacks the support of evidence-based medical evidence. We aim at this problem to guide the precision treatment of IgAN.

Methods

Embase, Pubmed, Cochrane Library, and Web of Science were searched systematically until February 24th, 2024, for publications on ML-based diagnosis and prognosis of IgAN. Subgroup analysis or meta-regression was conducted according to modeling method, follow-up time, endpoint definition, and variable type. Further, the rank sum test was applied to compare the discrimination ability of prognosis.

Results

A total of 47 studies involving 51,935 patients were eligible. Among the 38 diagnostic models, the pooled C-index was 0.902 (95 % CI: 0.878-0.926) in 27 diagnostic models. Of the 162 prognostic models, the C-index for model discrimination of 144 prognostic models was 0.838 (95 % CI: 0.827-0.850) in training. The overall discrimination ability of prognosis was as follows: COX regression > new ML models (e.g. ANN, DT, RF, SVM, XGBoost) > traditional ML models (logistic regression) > Naïve Bayesian network (P < 0.05). External validation of IIgAN-RPT in 19 models showed a pooled C-index of 0.801 (95 % CI: 0.784-0.817).

Conclusions

New ML models have shown application values that are as good as traditional ML models, both in diagnosis and prognosis. In addition, future models are desired to use a more sensitive prognostic endpoint (albuminuria), improve predictive ability in moderate progression risk, and ultimately translate into clinically applicable intelligent tools.

External Validation of the International IgA Nephropathy Prediction Tool in Older Adult Patients

Purpose

The International IgA Nephropathy Prediction Tool (IIgAN-PT) can predict the risk of End-stage renal disease (ESRD) or estimated glomerular filtration rate (eGFR) decline ≥ 50% for adult IgAN patients. Considering the differential progression between older adult and adult patients, this study aims to externally validate its performance in the older adult cohort.

Patients and Methods

We analyzed 165 IgAN patients aged 60 and above from six medical centers, categorizing them by their predicted risk. The primary outcome was a ≥50% reduction in estimated glomerular filtration rate (eGFR) or kidney failure. Evaluation of both models involved concordance statistics (C-statistics), time-dependent receiver operating characteristic (ROC) curves, Kaplan-Meier survival curves, and calibration plots. Comparative reclassification was conducted using net reclassification improvement (NRI) and integrated discrimination improvement (IDI).

Results

The study included 165 Chinese patients (median age 64, 60% male), with a median follow-up of 5.1 years. Of these, 21% reached the primary outcome. Both models with or without race demonstrated good discrimination (C-statistics 0.788 and 0.790, respectively). Survival curves for risk groups were well-separated. The full model without race more accurately predicted 5-year risks, whereas the full model with race tended to overestimate risks after 3 years. No significant reclassification improvement was noted in the full model without race (NRI 0.09, 95% CI: -0.27 to 0.34; IDI 0.003, 95% CI: -0.009 to 0.019).

Conclusion

: Both models exhibited excellent discrimination among older adult IgAN patients. The full model without race demonstrated superior calibration in predicting the 5-year risk.

Haemoglobin, albumin, lymphocyte, and platelet score as an independent predictor for renal prognosis in IgA nephropathy

Objective

The haemoglobin, albumin, lymphocyte, and platelet (HALP) score, a convenient and composite laboratory biomarker, can reflect inflammation and systemic nutritional status. This study was performed to investigate the effect of the HALP score on the prognosis of patients with IgA nephropathy (IgAN).

Methods

This is a retrospective single centre study that enrolled 895 biopsy-confirmed IgAN patients from June 2019 to June 2022 who were followed for more than 1 year. Kaplan-Meier curves and Cox regression analyses were performed to determine the relationship between HALP and adverse outcomes. The restricted cubic splines was used to identify the possible associations. The optimal cut-off value of HALP for renal poor outcome was identified by the area under the receiver operating characteristic curve (AUC).

Results

A total of 895 patients finally participated in the study and were divided into three groups (tertial 1-3) according to the baseline HALP score. More severe clinicopathologic features were observed in the lower HALP group, and Kaplan-Meier analysis showed patients in tertial 1 had a higher risk of kidney failure than the other groups (log-rank=11.02, P= 0.004). Multivariate Cox regression revealed that HALP score was an independent risk factor for renal prognosis in IgAN (adjusted HR: 0.967, 95% CI: 0.945-0.990, P = 0.006). The results of subgroup analysis suggested that HALP was more important in patients under the age of 50, BMI ≤ 23.9 and eGFR ≤ 90 mL/min/1.73 m2. The best cut-off HALP for renal survival was 38.83, sensitivity 72.1%, and specificity 55.9% (AUC: 0.662). Patients were further grouped according to HALP cut-off values and propensity matched. Multivariate Cox regression analysis revealed that HALP remained an independent predictor of IgAN in the matched cohort (HR 0.222, CI: 0.084-0.588, P=0.002).

Conclusion

HALP is a novel and potent composite parameter to predict kidney outcome in patients with IgAN.

Kidney Failure Attributed to Immunoglobulin A Nephropathy: A USRDS Retrospective Cohort Study of Epidemiology, Treatment Modalities, and Economic Burden

Rationale & Objective

This study describes the epidemiology, characteristics, and outcomes of patients with immunoglobulin A nephropathy (IgAN)-attributed kidney failure in the US Renal Data System (USRDS) from 2008 to 2018, including health care resource utilization and costs among patients with Medicare-linked data.

Study Design

Retrospective cohort study.

Setting & Population

Patients with IgAN-attributed kidney failure in the USRDS.

Outcomes

Prevalence/incidence, clinical/demographic characteristics, time to kidney transplant, and health care resource utilization and costs.

Analytical Approach

Patients with IgAN as primary cause of kidney failure (IgAN cohort) were followed from USRDS registration (index date) until data end/death. Prevalence/incidence were calculated per 1,000,000 US persons. Demographic and clinical characteristics at index and treatment modality during follow-up were summarized. Time from index to kidney transplant was assessed using Kaplan-Meier and competing risk analyses. Health care resource utilization and health care costs were reported among patients with 1 year Medicare Part A+B coverage postindex, including or excluding those who died (Medicare Coverage and 1-year Medicare Coverage subgroups, respectively).

Results

The IgAN cohort, Medicare Coverage, and 1-year Medicare Coverage subgroups included 10,101, 1,696, and 1,510 patients, respectively. Mean annual period prevalence and incidence of IgAN-attributed kidney failure were 39.3 and 2.9 per 1,000,000 US persons, respectively. Initial treatment was in-center hemodialysis (63.1%) or kidney transplant (15.1%). Year 1 and 5 kidney transplant rates were 5% and 17%, respectively, accounting for competing risk of death. In the Medicare Coverage and 1-year Medicare Coverage subgroups, 74.4% and 72.3%, respectively, required inpatient admission, 67.3% and 64.4%, respectively, visited the emergency room, and mean total health care costs were $6,293 (SD: $6,934) and $5,284 ($3,455), respectively, per-patient-per-month in the year postindex.

Limitations

Drug costs may be underestimated as Medicare Part D coverage was not required; kidney acquisition costs were unavailable.

Conclusions

IgAN-attributed kidney failure is associated with substantial clinical and economic burdens. Novel therapies for IgAN that delay kidney failure are needed.

A novel prognostic nomogram predicts premature failure of kidney allografts with IgA nephropathy recurrence

BACKGROUND

Recurrence of immunoglobulin A nephropathy (IgAN) limits graft survival in kidney transplantation. However, predictors of a worse outcome are poorly understood.

METHODS

Among 442 kidney transplant recipients (KTRs) with IgAN, 83 (18.8%) KTRs exhibited biopsy-proven IgAN recurrence between 1994 and 2020 and were enrolled in the derivation cohort. A multivariable Cox model predicting allograft loss based on clinical data at the biopsy and a web-based nomogram were developed. The nomogram was externally validated using an independent cohort (n = 67).

RESULTS

Patient age <43 years {hazard ratio [HR] 2.20 [95% confidence interval (CI) 1.41-3.43], P < .001}, female gender [HR 1.72 (95% CI 1.07-2.76), P = .026] and retransplantation status [HR 1.98 (95% CI 1.13-3.36), P = .016] were identified as independent risk factors for IgAN recurrence. Patient age <43 years [HR 2.77 (95% CI 1.17-6.56), P = .02], proteinuria >1 g/24 hours [HR 3.12 (95% CI 1.40-6.91), P = .005] and C4d positivity [HR 2.93 (95% CI 1.26-6.83), P = .013] were found to be associated with graft loss in patients with IgAN recurrence. A nomogram predicting graft loss was constructed based on clinical and histological variables, with a C statistic of 0.736 for the derivation cohort and 0.807 for the external validation cohort.

CONCLUSIONS

The established nomogram identified patients with recurrent IgAN at risk for premature graft loss with good predictive performance.

Validation of the international IgA nephropathy prediction tool in a French cohort beyond 10 years after diagnosis

INTRODUCTION

The International IgA Nephropathy Network developed a tool (IINN-PT) for predicting the risk of end-stage renal disease (ESRD) or a 50% decline in the estimated glomerular filtration rate (eGFR). We aimed to validate this tool in a French cohort with longer follow-up than previously published validation studies.

METHODS

The predicted survival of patients with biopsy-proven immunoglobulin A nephropathy (IgAN) from the Saint Etienne University Hospital cohort was computed with IINN-PT models with or without ethnicity. The primary outcome was the occurrence of either ESRD or a 50% decline in eGFR. The models' performances were evaluated through c-statistics, discrimination and calibration analysis.

RESULTS

There were 473 patients with biopsy-proven IgAN, with a median follow-up of 12.4 years. Models with and without ethnicity showed areas under the curve (95% confidence interval) of 0.817 (0.765; 0.869) and 0.833 (0.791; 0.875) and R2D of 0.28 and 0.29, respectively, and an excellent discrimination of groups of increasing predicted risk (P < .001). The calibration analysis was good for both models up to 15 years after diagnosis. The model without ethnicity exhibited a mathematical issue of survival function after 15 years.

DISCUSSION

The IINN-PT provided good performances even after 10 years post-biopsy as showed by our study based on a cohort with a longer follow-up than previous cohorts (12.4 versus <6 years). The model without ethnicity exhibited better performances up to 15 years but became aberrant beyond this point due to a mathematical issue affecting the survival function. Our study sheds light on the usefulness of integrating ethnicity as a covariable for prediction of IgAN course.

Machine learning in predicting T-score in the Oxford classification system of IgA nephropathy

Background

Immunoglobulin A nephropathy (IgAN) is one of the leading causes of end-stage kidney disease (ESKD). Many studies have shown the significance of pathological manifestations in predicting the outcome of patients with IgAN, especially T-score of Oxford classification. Evaluating prognosis may be hampered in patients without renal biopsy.

Methods

A baseline dataset of 690 patients with IgAN and an independent follow-up dataset of 1,168 patients were used as training and testing sets to develop the pathology T-score prediction (T pre) model based on the stacking algorithm, respectively. The 5-year ESKD prediction models using clinical variables (base model), clinical variables and real pathological T-score (base model plus T bio), and clinical variables and T pre (base model plus T pre) were developed separately in 1,168 patients with regular follow-up to evaluate whether T pre could assist in predicting ESKD. In addition, an external validation set consisting of 355 patients was used to evaluate the performance of the 5-year ESKD prediction model using T pre.

Results

The features selected by AUCRF for the T pre model included age, systolic arterial pressure, diastolic arterial pressure, proteinuria, eGFR, serum IgA, and uric acid. The AUC of the T pre was 0.82 (95% CI: 0.80-0.85) in an independent testing set. For the 5-year ESKD prediction model, the AUC of the base model was 0.86 (95% CI: 0.75-0.97). When the T bio was added to the base model, there was an increase in AUC [from 0.86 (95% CI: 0.75-0.97) to 0.92 (95% CI: 0.85-0.98); P = 0.03]. There was no difference in AUC between the base model plus T pre and the base model plus T bio [0.90 (95% CI: 0.82-0.99) vs. 0.92 (95% CI: 0.85-0.98), P = 0.52]. The AUC of the 5-year ESKD prediction model using T pre was 0.93 (95% CI: 0.87-0.99) in the external validation set.

Conclusion

A pathology T-score prediction (T pre) model using routine clinical characteristics was constructed, which could predict the pathological severity and assist clinicians to predict the prognosis of IgAN patients lacking kidney pathology scores.

Albumin-to-fibrinogen ratio is an independent predictor of corticosteroid response and prognosis in patients with IgA nephropathy

BACKGROUND

The objective of this study was to investigate whether the albumin-to-fibrinogen ratio (AFR) can predict corticosteroid response and prognosis prediction among IgA nephropathy (IgAN) patients.

METHODS

Eligible participants with diagnosed IgAN who were scheduled to receive corticosteroid therapy for persistent proteinuria were recruited. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the predictive value of AFR or estimated glomerular filtration rate (eGFR) for corticosteroid response in IgAN patients. Risk factors for corticosteroid response and prognosis were validated using univariate and multivariate Cox proportional analyses.

RESULTS

AFR and eGFR were both effective predictors of corticosteroid response in IgAN patients, with area under the curve (AUC) values of 0.686 and 0.643, respectively (P < 0.001 and P = 0.002). Baseline AFR level at biopsy was an independent risk factor for remission after corticosteroid therapy (HR: 2.38, 95% CI 1.32-4.07, P = 0.015), 50% decline in eGFR (HR: 0.78, 95% CI 0.69-0.89, P = 0.025), kidney failure (HR: 2.46, 95%CI 1.16-3.71, P = 0.016), and a composite event (HR: 2.13, 95%CI 1.28-3.34, P = 0.009) in IgAN patients.

CONCLUSIONS

AFR level at biopsy was a potential predictor of corticosteroid response and prognosis among IgAN patients.

Post-hoc analysis of a tool to predict kidney failure in patients with IgA nephropathy

BACKGROUND

Recently, a tool based on two different artificial neural networks has been developed. The first network predicts kidney failure (KF) development while the second predicts the time frame to reach this outcome. In this study, we conducted a post-hoc analysis to evaluate the discordant results obtained by the tool.

METHODS

The tool performance was analyzed in a retrospective cohort of 1116 adult IgAN patients, as were the causes of discordance between the predicted and observed cases of KF.

RESULTS

There was discordance between the predicted and observed KF in 216 IgAN patients (19.35%) all of whom were elderly, hypertensive, had high serum creatinine levels, reduced renal function and moderate or severe renal lesions. Many of these patients did not receive therapy or were non-responders to therapy. In other IgAN patients the tool predicted KF but the outcome was not reached because patients responded to therapy. Therefore, in the discordant group (prediction did not match the observed outcome) the proportion of patients having or not having KF was strongly associated with treatment (P < 0.0001).

CONCLUSIONS

The post-hoc analysis shows that discordance in a low number of patients is not an error, but rather the effect of positive response to therapy. Thus, the tool could both help physicians to determine the prognosis of the disease and help patients to plan for their future.

Clinical relevance of glomerular C4d deposition in children with early IgA nephropathy or Henoch-Schönlein purpura nephropathy

BACKGROUND

Both IgA nephropathy (IgAN) and Henoch-Schönlein purpura nephropathy (HSPN) are characterized by glomerular mesangial IgA deposition. Several large studies on adults have suggested that glomerular C4d deposition has prognostic value in IgAN. However, there are few relevant studies on the clinical value of C4d deposition in children with IgAN or HSPN.

METHODS

We performed a retrospective cohort study in pediatric patients with IgAN or HSPN. Clinicopathological data were collected at the time of kidney biopsy. Kidney C4d deposition was analyzed by immunohistochemistry. The end point was defined as a ≥ 20% decrease in estimated glomerular filtration from baseline.

RESULTS

We enrolled 75 children, including 36 children with IgAN and 39 with HSPN. The prevalence of C4d deposition was 36% (27/75). C4d deposition was more abundant in children with proteinuria ≥ 50 mg/kg/day (51.9% versus 20.8%, P = 0.006) or nephrotic syndrome (37.0% versus 10.4%, P = 0.006). Mesangial hypercellularity (hazard ratio [HR], 5.745, 95% confidence interval [CI], 1.670-19.761, P = 0.006) and IgM deposition (HR, 4.522, 95% CI, 1.321-15.478, P = 0.016) were associated with C4d deposition. After a median follow-up of 22 months, seven (19.4%) IgAN patients and one (2.6%) HSPN patient had decreased kidney function. In children with IgAN, positive C4d was associated with decreased kidney function (P = 0.047).

CONCLUSION

Glomerular C4d deposition was associated with mesangial hypercellularity and glomerular IgM deposition in IgAN and HSPN. Glomerular C4d deposition may be a risk factor for eGFR decline in children with IgAN. A higher resolution version of the Graphical abstract is available as Supplementary information.

Time-Averaged Hematuria as a Prognostic Indicator of Renal Outcome in Patients with IgA Nephropathy

We aim to investigate the association of time-averaged hematuria (TA-hematuria) with the progression of IgA nephropathy (IgAN). Based on TA-hematuria during follow-up, 152 patients with IgAN were divided into a hematuria remission group (≤28 red blood cells [RBCs]/μL) and a persistent hematuria group (>28 RBCs/μL). The persistent hematuria group had a higher percentage of patients with macroscopic hematuria, lower levels of hemoglobin and TA-serum albumin, and more severe renal pathologic lesions. The composite endpoint is defined as a doubling of the baseline SCr level (D-SCr), or the presence of ESRD. During the mean follow-up of 58.08 ± 23.51 months, 15 patients (9.9%) reached the primary outcome of ESRD and 19 patients (12.5%) reached the combined renal endpoint. Kaplan-Meier analysis showed that the persistent hematuria group had a lower renal survival rate. The persistent hematuria patients who were incorporated with proteinuria (≥1.0 g/day) and low TA-serum albumin (<40 g/L) had the worst renal outcomes. Multivariate Cox regression indicated that TA-hematuria (hazard ratio [HR] = 0.004, 95% CI: 0.001, 0.008; p = 0.010) was independently associated with the progression of IgAN. Receiver operating characteristic analysis indicated the optimal TA-hematuria cutoff value for predicting the progression of IgAN was 201.21 RBCs/μL in females and 37.25 RBCs/μL in males.

Association between hemoglobin and chronic kidney disease progression: a secondary analysis of a prospective cohort study in Japanese patients

OBJECTIVE

Anemia has been reported as a risk factor for chronic kidney disease (CKD) progression. However, there are still few studies examining the relationship between specific hemoglobin (Hb) levels and renal prognosis and renal function decline simultaneously. Meanwhile, the possible non-linear relationship between Hb and CKD progression also deserves further exploration. On that account, our primary goal is to explore the link of Hb on renal prognosis and renal function decline in patients with CKD.

METHODS

This study was a secondary analysis of a prospective cohort study, which consecutively and non-selectively collected 962 participants from the research of CKD-ROUTE in Japan from November 2010 to December 2011. We used the Cox proportional-hazards and linear regression models to evaluate the independent association between baseline Hb and renal prognosis (renal composite endpoint, initiation of dialysis during follow-up or 50% decline in eGFR from baseline) and renal function decline(annual eGFR decline), respectively. A multivariate Cox proportional hazards regression analysis with cubic spline functions model and smooth curve fitting (penalized spline method) were conducted to address Hb and CKD prognosis's non-linearity. At the same time, a generalized additive model (GAM) and smooth curve fitting (penalized spline method) was conducted to explore the exact shape of the curve between Hb and renal function decline. Additionally, we did a series of sensitivity analyses to ensure the robustness of the results. Moreover, we conducted subgroup analyses.

RESULTS

The mean age of the included patients was 67.35 ± 13.56 years old, and 69.65% were male. The mean baseline Hb and estimated glomerular filtration rate (eGFR) was 12.06 ± 2.21 g/dL and 33.04 ± 18.01 ml/min per 1.73 m². The annual decline in eGFR was 2.09 mL/min/1.73 m²/year. During a median follow-up time of 33.5 months, 252(26.2%) people experienced renal composite endpoint. After adjusting covariates, the results showed that Hb was negatively associated with renal composite endpoint (HR = 0.836, 95%CI: 0.770, 0.907) and renal function decline (β = -0.436, 95%CI: -0.778, -0.093). There was also a non-linear relationship between Hb and renal composite endpoint, and the inflection point of Hb was 8.6 g/dL. The effect sizes(HR) on the left and right sides of the inflection point were 1.257 (0.841, 1.878) and 0.789 (0.715, 0.870), respectively. And the sensitive analysis demonstrated the robustness of the results. Subgroup analysis showed that Hb was more strongly associated with the renal composite endpoint in non-hypertensive, SBP < 140 mmHg, urine protein-to-creatinine ratio (UPCR) < 0.5 g/gCr, and diuretic use patients. In contrast, the weaker association was probed in hypertensive and non-diuretic use patients and the patients with SBP ≥ 140 mmHg, and UPCR ≥ 0.5 g/gCr.

CONCLUSION

This study demonstrates a negative and non-linear relationship between Hb and renal prognosis and renal function decline in Japanese CKD patients. Hb is strongly related to renal prognosis when Hb is above 8.6 g/dL.

Prognosis analysis of necroptosis-related genes in colorectal cancer based on bioinformatic analysis

Background: Colorectal cancer (CRC) is one gastrointestinal malignancy, accounting for 10% of cancer diagnoses and cancer-related deaths worldwide each year. Therefore, it is urgent to identify genes involved in CRC predicting the prognosis.

Methods: CRC’s data were acquired from the Gene Expression Omnibus (GEO) database (GSE39582 and GSE41258 datasets) and The Cancer Genome Atlas (TCGA) database. The differentially expressed necroptosis-related genes (DENRGs) were sorted out between tumor and normal tissues. Univariate Cox regression analysis and least absolute shrinkage and selectionator operator (LASSO) analysis were applied to selected DENRGs concerning patients’ overall survival and to construct a prognostic biomarker. The effectiveness of this biomarker was assessed by the Kaplan–Meier curve and the receiver operating characteristic (ROC) analysis. The GSE39582 dataset was utilized as external validation for the prognostic signature. Moreover, using univariate and multivariate Cox regression analyses, independent prognostic factors were identified to construct a prognostic nomogram. Next, signaling pathways regulated by the signature were explored through the gene set enrichment analysis (GSEA). The single sample gene set enrichment analysis (ssGSEA) algorithm and tumor immune dysfunction and exclusion (TIDE) were used to explore immune correlation in the two groups, high-risk and low-risk ones. Finally, prognostic genes’ expression was examined in the GSE41258 dataset.

Results: In total, 27 DENRGs were filtered, and a necroptosis-related prognostic signature based on 6 DENRGs was constructed, which may better understand the overall survival (OS) of CRC. The Kaplan–Meier curve manifested the effectiveness of the prognostic signature, and the ROC curve showed the same result. In addition, univariate and multivariate Cox regression analyses revealed that age, pathology T, and risk score were independent prognostic factors, and a nomogram was established. Furthermore, the prognostic signature was most significantly associated with the apoptosis pathway. Meanwhile, 24 immune cells represented significant differences between two groups, like the activated B cell. Furthermore, 32 immune checkpoints, TIDE scores, PD-L1 scores, and T-cell exclusion scores were significantly different between the two groups. Finally, a 6-gene prognostic signature represented different expression levels between tumor and normal samples significantly in the GSE41258 dataset.

Conclusion: Our study established a signature including 6 genes and a prognostic nomogram that could significantly assess the prognosis of patients with CRC.

Validation of two IgA nephropathy risk-prediction tools using a cohort with a long follow-up

BACKGROUND

Recently, two immunoglobulin A nephropathy prediction tools were developed that combine clinical and histopathological parameters. The International IgAN Prediction Tool predicts the risk for 50% declines in the estimated glomerular filtration rate or end-stage renal disease up to 80 months after diagnosis. The IgA Nephropathy Clinical Decision Support System uses artificial neural networks to estimate the risk for end-stage renal disease. We aimed to externally validate both prediction tools using a Norwegian cohort with a long-term follow-up.

METHODS

We included 306 patients with biopsy-proven primary immunoglobulin A nephropathy in this study. Histopathologic samples were retrieved from the Norwegian Kidney Biopsy Registry and reclassified according to the Oxford classification. We used discrimination and calibration as principles for externally validating the prognostic models.

RESULTS

The median patient follow-up was 17.1 years. A cumulative dynamic time-dependent receiver operating characteristic analysis showed area under the curve values of ranging from 0.90 at 5 years to 0.83 at 20 years for the International IgAN Prediction Tool, while time-naive analysis showed an area under the curve value at 0.83 for the IgA Nephropathy Clinical Decision Support System. The International IgAN Prediction Tool was well calibrated, while the IgA Nephropathy Clinical Decision Support System tends to underestimate risk for patients with higher risk, and overestimates risk in the lower risk categories.

CONCLUSIONS

We have externally validated two prediction tools for IgA nephropathy. The International IgAN Prediction Tool performed well, while the IgA Nephropathy Clinical Decision Support System has some limitations.

An evaluation of the roles of hematuria and uric acid in defining the prognosis of patients with IgA nephropathy

In recent years, many significant advances have been made in determining which clinical manifestations and pathologic lesions can provide prognostic information for patients with IgA nephropathy (IgAN). However, some important questions remain, including the long-term consequences of hematuria, both macroscopic (MH) and microscopic (mH), in patients with IgAN. The importance of distinguishing patients who have a single episode of MH of long duration from those with recurrent episodes of short duration and the prognostic importance of the episodes of acute kidney injury (AKI) that sometimes accompany episodic MH will be discussed. Studies that have evaluated the mechanisms that may be responsible for recurrent MH and the toxic effects of red blood cells (RBCs), or their constituents, on kidney tubules will also be addressed. In the last section, I will review the evidence that hyperuricemia (HU) may be a significant independent risk factor for progressive kidney disease in patients with IgAN.

Prediction of prognosis in immunoglobulin a nephropathy patients with focal crescent by machine learning

BACKGROUND AND OBJECTIVES

Immunoglobulin a nephropathy (IgAN) is the most common primary glomerular disease in the world, with different clinical manifestations, varying severity of pathological changes, common complications of crescent formation in different proportions, and great individual heterogeneous in clinical outcomes. Therefore, we aim to develop a machine learning (ML) based predictive model for predicting the prognosis of IgAN with focal crescent formation and without obvious chronic renal lesions (glomerulosclerosis <25%).

MATERIALS

We retrospectively reviewed biopsy-proven IgAN patients in our hospital and cooperative hospital from 2005 to 2017. The method of feature importance of random forest (RF) was applied to conduct feature exploration of feature variables to establish the characteristic variables that are closely related to the prognosis of focal crescent IgAN. Multiple ML algorithms were attempted to establish the prediction models. The area under the precision-recall curve (AUPRC) and the area under the receiver operating characteristic curve (AUROC) were applied to evaluate the predictive performance via three-fold cross validation (namely 2 training sets and 1 validation set).

RESULTS

RF was used to screen the important features, the top three of which were baseline estimated glomerular filtration rate (eGFR), serum creatine and triglyceride. Ten important features were selected as important predictors for modeling on the basis of data-driven and medical selection, predictors include: age, baseline eGFR, serum creatine, serum triglycerides, complement 3(C3), proteinuria, mean arterial pressure (MAP) and Hematuria, crescents proportion of glomeruli, Global crescent proportion of glomeruli. In a variety of ML algorithms, the support vector machine (SVM) algorithm displayed better predictive performance, with Precision of 0.77, Recall of 0.77, F1-score of 0.73, accuracy of 0.77, AUROC of 79.57%, and AUPRC of 76.5%.

CONCLUSIONS

The SVM model is potentially useful for predicting the prognosis of IgAN patients with focal crescent shape and without obvious chronic renal lesions.

The International IgA nephropathy network (IIgANN) prediction tool underestimates disease progression in Indian patients

Introduction

International IgA nephropathy (IgAN) network (IIgANN) prediction tool was developed to predict risk of progression in IgAN. We attempted to externally validate this tool in an Indian cohort because the original study did not include Indian patients.

Methods

Adult patients with primary IgAN were stratified to low, intermediate, higher, and highest risk groups, as per the original model. Primary outcome was reduction in estimated glomerular filtration rate (eGFR) by >50% or kidney failure. Both models were evaluated using discrimination: concordance statistics (C-statistics), time-dependent receiver operating characteristic (ROC) curves, R²d, Kaplan–Meier survival curves between risk groups and calibration plots. Reclassification with net reclassification improvement and integrated discrimination improvement (IDI) was used to compare the 2 models with and without race.

Results

A total of 316 patients with median follow-up of 2.8 years had 87 primary outcome events. Both models with and without race showed reasonable discrimination (C-statistics 0.845 for both models, R²d 49.9% and 44.7%, respectively, and well-separated survival curves) but underestimated risk of progression across all risk groups. The calibration slopes were 1.234 (95% CI: 0.973–1.494) and 1.211 (95% CI: 0.954–1.468), respectively. Both models demonstrated poor calibration for predicting risk at 2.8 and 5 years. There was limited improvement in risk reclassification risk at 5 and 2.8 years when comparing model with and without race.

Conclusion

IIgANN prediction tool showed reasonable discrimination of risk in Indian patients but underestimated the trajectory of disease progression across all risk groups.

A Novel Scoring System Based on Oxford Classification Indicating Steroid Therapy Use for IgA Nephropathy

Introduction

The usefulness of the Oxford classification (MEST-C score) for deciding the management approach for IgA nephropathy (IgAN) remains unclear.

Methods

Effects of steroid therapy on the long-term prognosis for all 858 patients with IgAN and patients classified according to each MEST-C score were evaluated using Kaplan-Meier and Cox regression analyses. Steroid responder score (SRS) and steroid nonresponder score (SNRS) were determined using individual pathology scores when steroids were found to be independently associated, or not, with clinical benefits. In addition, the effects of steroid therapy according to the total SRS/SNRS were analyzed.

Results

Steroid therapy improved the 20-year renal survival rates of patients with IgAN after matching (steroids[+] vs. steroids[−]; estimated glomerular filtration rate [eGFR] [ml/min per 1.73 m²]: 79.4 vs. 77.0, not significant; proteinuria [g/d]: 0.80 vs. 0.62, not significant; renal survival rate: 75.5% vs. 61.7%; P = 0.025) and of patients with M1, E1, S1, C1+2, and T0 scores. Therefore, we considered the total of the M1, E1, S1, and C1+2 scores (point 0: low, 1–2: medium, and 3–4: high) as the SRS and the total of the T1+2 scores (0: low and 1: high) as the SNRS. Multivariate Cox regression analyses revealed that steroid therapy improved the renal prognosis of patients with IgAN with high SRS and any SNRS, unlike patients with IgAN with medium SRS and any SNRS.

Conclusion

Patients with M1, E1, S1, and C1+2 scores responded to steroid therapy; however, those with T1+2 scores did not. Although a high SRS was a useful indicator for steroid therapy, SNRS indicated resistance to steroid therapy.

Transmembrane signaling molecules play a key role in the pathogenesis of IgA nephropathy: a weighted gene co-expression network analysis study

BACKGROUND

Immunoglobulin A nephropathy (IgAN) is one of the most common primary glomerulonephritis and a serious health concern worldwide; though still the underlying molecular mechanisms of IgAN are yet to be known and there is no efficient treatment for this disease. The main goal of this study was to explore the IgAN underlying pathogenic pathways, plus identifying the disease correlated modules and genes using the weighted gene co-expression network analysis (WGCNA) algorithm.

RESULTS

GSE104948 dataset (the expression data from glomerular tissue of IgAN patients) was analyzed and the identified differentially expressed genes (DEGs) were introduced to the WGCNA algorithm for building co-expression modules. Genes were classified into six co-expression modules. Genes of the disease's most correlated module were mainly enriched in the immune system, cell-cell communication and transmembrane cell signaling pathways. The PPI network was constructed by genes in all the modules and after hub-gene identification and validation steps, 11 genes, mostly transmembrane proteins (CD44, TLR1, TLR2, GNG11, CSF1R, TYROBP, ITGB2, PECAM1), as well as DNMT1, CYBB and PSMB9 were identified as potentially key players in the pathogenesis of IgAN. In the constructed regulatory network, hsa-miR-129-2-3p, hsa-miR-34a-5p and hsa-miR-27a-3p, as well as STAT3 were spotted as top molecules orchestrating the regulation of the hub genes.

CONCLUSIONS

The excavated hub genes from the hearts of co-expressed modules and the PPI network were mostly transmembrane signaling molecules. These genes and their upstream regulators could deepen our understanding of IgAN and be considered as potential targets for hindering its progression.

A Validation Study Comparing Risk Prediction Models of IgA Nephropathy

We aimed to validate three IgAN risk models proposed by an international collaborative study and another CKD risk model generated by an extended CKD cohort with our multicenter Chinese IgAN cohort. Biopsy-proven IgAN patients with an eGFR ≥15 ml/min/1.73 m² at baseline and a minimum follow-up of 6 months were enrolled. The primary outcomes were a composite outcome (50% decline in eGFR or ESRD) and ESRD. The performance of those models was assessed using discrimination, calibration, and reclassification. A total of 2,300 eligible cases were enrolled. Of them, 288 (12.5%) patients reached composite outcome and 214 (9.3%) patients reached ESRD during a median follow-up period of 30 months. Using the composite outcome for analysis, the Clinical, Limited, Full, and CKD models had relatively good performance with similar C statistics (0.81, 0.81, 0.82, and 0.82, respectively). While using ESRD as the end point, the four prediction models had better performance (all C statistics > 0.9). Furthermore, subgroup analysis showed that the models containing clinical and pathological variables (Full model and Limited model) had better discriminatory abilities than the models including only clinical indicators (Clinical model and CKD model) in low-risk patients characterized by higher baseline eGFR (≥60 ml/min/1.73 m²). In conclusion, we validated recently reported IgAN and CKD risk models in our Chinese IgAN cohort. Compared to pure clinical models, adding pathological variables will increase performance in predicting ESRD in low-risk IgAN patients with baseline eGFR ≥60 ml/min/1.73 m².

Epidemiology and risk factors for progression in Chinese patients with IgA nephropathy

BACKGROUND

IgA nephropathy (IgAN) is one of the main causes of primary glomerulonephritis worldwide, and it is also the main primary disease leading to chronic kidney disease. The purpose of this study is to evaluate the epidemiology and risk factors for progression in Chinese patients with IgAN.

METHODS

In this retrospective study, 246 patients with renal biopsy-proven IgAN were enrolled from January 2012 to June 2018. The patients' data were divided into two groups according to eGFR at the end of follow-up: a high-eGFR group (eGFR≥60ml/min) and a low-eGFR group (eGFR<60ml/min).

RESULTS

At the end of the study, we identified 49 (19.92%) patients with low-eGFR from 246 IgAN patients. Renal function, represented by serum creatinine, urea nitrogen and cystatin-C, was significantly decreased in the low-eGFR group (P<0.001 for all) at the time of renal biopsy. Compared with the high-eGFR group, the age, mean arterial blood pressure (MAP), proteinuria, cholesterol, triglycerides and serum uric acid were significantly higher (P<0.05 for all). According to the Oxford evaluation, the proportion of S1-2 (59.2%) and T1-2 (65.3%) was significantly increased (P<0.001 for both) and the proportion that had a MEST-C score ≥3 was statistically increased in the low-eGFR group (83.7%, P=0.001).

CONCLUSIONS

Male, MAP, haematuria, Scr, cholesterol, hemoglobin, Lee classification more than 3 and C1-2 are independent risk factors for low-eGFR in Chinese IgAN patients.

Relationship between blood neutrophil-lymphocyte ratio and renal tubular atrophy/interstitial fibrosis in IgA nephropathy patients

BACKGROUND

The study aimed to explore the relationship between neutrophil-lymphocyte ratio(NLR) in peripheral blood and renal tubular atrophy/interstitial fibrosis and to evaluate the clinical significance of NLR in IgA nephropathy (IgAN) patients.

METHODS

A Total of 263 IgAN patients were included. The participants were categorized into four groups based on quartile of NLR. The clinical data, pathological features, and 2-year renal survival rates were compared among the four groups. The independent factors affecting renal tubular atrophy/interstitial fibrosis in IgAN were determined by multivariate linear regression analysis.

RESULTS

The percentage of renal tubular atrophy/interstitial fibrosis increased with the increase of NLR level (p=0.003). The tubular atrophy/interstitial fibrosis score T1 and T2 in Group Q4 was 40%, which was higher than that of other groups, especially Group Q1 (22.73%, p=0.033) and Group Q3 (22.39%, p=0.029). NLR [β=1.230, 95%CI (0.081, 2.379), p=0.036] might be an independent factor affecting renal tubular atrophy/interstitial fibrosis in IgAN. The area under curve predicted by NLR was 0.596 (95%CI 0.534~0.656, p=0.007) with the specificity 88.24% and the optimal critical value of NLR 3.25. Fourteen patients progressed to end-stage renal disease within 2 years, and the 2-year survival rate of kidney was 93.49%. The renal survival rate in Group Q4 was 87.04%, lower than that in other three groups, especially Group Q1 (98.11%, p=0.029).

CONCLUSION

NLR was correlated with the level of renal tubular atrophy/interstitial fibrosis and might be a significant factor for predicting the prognosis in the IgAN.

BACKGROUND

IgA nephropathy (IgAN) is an important cause of the end stage renal disease (ESRD). The study aimed to explore the relationship between neutrophil-lymphocyte ratio (NLR) in peripheral blood and renal tubular atrophy/interstitial fibrosis, and to evaluate the clinical significance of NLR in IgA nephropathy (IgAN) patients.

METHODS

Total 263 IgAN patients confirmed by renal biopsy pathology were included from January 2013 to May 2018 in Ningbo Hwamei Hospital, University of Chinese Academy of Sciences. The peripheral blood samples were taken from these participants and the NLR was analyzed. The participants were categorized into four groups based on the median and upper and lower quartile of NLR, which were Group Q1 (NLR<1.64), Group Q2 (1.64≤NLR<2.19), Group Q3 (2.19≤NLR<3.00), and Group Q4 (NLR≥3.00), respectively. The clinical data and pathological features were compared among four groups. The independent factors affecting renal tubular atrophy/interstitial fibrosis in IgAN were determined by multivariate linear regression analysis. The diagnostic ability of NLR for renal tubular atrophy/interstitial fibrosis was evaluated by the area under receiver operating characteristic curve (AUC). The 2-year renal survival rates were compared among the four groups.

RESULTS

The levels of white blood cell count, neutrophil count, highly sensitive C-reactive protein, and the percentage of renal tubular atrophy/interstitial fibrosis were increased while lymphocyte count and estimated glomerular filtration rate were decreased with the increase of NLR level (P < 0.05). The percentage of tubular atrophy/interstitial fibrosis 26%-50% (T1) and >50% (T2) in Group Q4 was 40%, which was higher than that of other groups, especially Group Q1 (22.73%) and Group Q3 (22.39%), with significant difference (P < 0.05). NLR [β = 1.230, 95%CI (0.081, 2.379), P = 0.036] might be an independent factor affecting renal tubular atrophy/interstitial fibrosis in IgAN according to multivariate linear regression analysis results. The AUC predicted by NLR was 0.596 (95%CI 0.534~0.656, P = 0.007) with the specificity 88.24%, the sensitivity 30.00% and the optimal critical value of NLR 3.25. Fourteen patients progressed to end-stage renal disease within 2 years; and the 2-year survival rate of kidney was 93.49%. The renal survival rate in Group Q4 was 87.04%, lower than that in other three groups, especially Group Q1 (98.11%), with significant difference (P < 0.05).

CONCLUSION

NLR was correlated with the level of renal tubular atrophy/interstitial fibrosis and might be an significant factor for predicting the prognosis in IgAN.

Serum Levels of miR-148b and Let-7b at Diagnosis May Have Important Impact in the Response to Treatment and Long-Term Outcome in IgA Nephropathy

Background/aims: Previous studies showed that two microRNAs, let-7b and miR-148, which regulate the O-glycosylation process of IgA1, may predict diagnosis of primary IgA nephropathy (IgAN). The combined analysis of their serum levels in calculated statistical models may act as serum biomarkers for the diagnosis of primary IgAN. In the present study, we aimed to assess their impact not only on clinical and histological findings at onset but also on renal function after a long-term follow-up. Patients and methods: We enrolled 61 Caucasian patients with biopsy-proven IgAN. Serum levels of miR-148b, let-7b, and galactose-deficient IgA1 (Gd-IgA1) at the time of diagnosis were measured using real-time quantitative PCR and enzyme-linked immunosorbent assay using the monoclonal antibody KM55, respectively. Their values along with calculated Models 1 and 2 were correlated with histologic scoring system (Oxford classification system) and with renal function at diagnosis and after 11.9 ± 6.6 years. Fifty-five healthy volunteers were enrolled as controls. Results: No significant correlation was found between miRNA and Gd-IgA1 levels and eGFR and proteinuria at diagnosis. A significant negative association was detected between the presence of crescents and serum levels of let-7b (p = 0.002), miR-148b (p = 0.01), and Models 1 and 2 (p = 0.02 and p = 0.007, respectively). At the end of follow-up, eGFR correlated with let-7b levels (p = 0.01), Model 1 (p = 0.002), and Model 2 (p = 0.004). Patients with fast progression of the renal damage had significantly increased levels of let-7b (p = 0.01), Model 1 (p = 0.003), and Model 2 (p = 0.005) compared to slow progressors, as did those who reached ESKD (p = 0.002, p = 0.001, and p = 0.001, respectively). Results were most prominent in those treated with corticosteroids. Finally, cut off levels in Models 1 and 2 could also predict the renal function outcome after long-term follow-up. Conclusions: Serum levels of let-7b and miR-148b and their combination, may serve as predictors for long-term renal function outcomes, particularly in patients treated with corticosteroids.

Glomerular C4 deposition and glomerulosclerosis predict worse renal outcomes in Chinese patients with IgA nephropathy

Background

Immunoglobulin A nephropathy (IgAN) is a clinical and pathological syndrome with heterogenous manifestation and progression. Complement activation is involved in the disease. However, the clinical significance of C4 deposition in IgAN is obscure.

Methods

A multicenter retrospective study was conducted in biopsy-proven IgAN patients. Based on mesangial C4 deposition, patients were divided into two groups. The baseline clinical data and immunopathological phenotypes were compared. The composite endpoint was defined as eGFR decline greater than 50%, doubling of baseline serum creatinine, the occurrence of end-stage renal disease (ESRD).

Results

A total of 642 IgAN patients were recruited, with 41 patients showing mesangial C4 deposition. The mesangial C4 positive group showed lower serum albumin, higher proteinuria, and a higher rate of IgG, IgM, and C1q mesangial deposition. After a median follow-up of 43.18 months, 81 (12.62%) patients achieved the composite endpoint. The multivariate Cox regression models identified glomerular C4 deposition (hazard ratios [HR] = 3.22, 95% confidence intervals [CI] = 1.51–6.87, p < 0.01), global sclerosis (G1 vs. G0, HR = 1.90, 95%CI = 1.02–3.52, p = 0.04; G2 vs. G0, HR = 3.72, 95%CI = 1.98–7.00, p < 0.01), male (HR = 1.80, 95%CI = 1.10–2.97, p = 0.02), serum creatinine (HR = 1.01, 95%CI = 1.00–1.01, p < 0.01), triglyceride (HR = 1.17, 95%CI = 1.01–1.35, p = 0.04), proteinuria (HR = 1.07, 95%CI = 1.01–1.13, p = 0.02), serum C3 level (HR = 0.05, 95%CI = 0.01–0.25, p < 0.01), and serum C4 level (HR = 99.59, 95%CI = 8.69–1140.89, p < 0.01) as independent risk factors for poor renal outcomes.

Conclusions

Glomerular mesangial C4 deposition and global sclerosis are independent predictors for poor prognosis in IgAN patients.

Correlation analysis between expression of histone deacetylase 6 and clinical parameters in IgA nephropathy patients

Background

It has been demonstrated that histone deacetylase 6 (HDAC6) is involved in various kidney diseases in experimental study. However, correlation between HDAC6 and clinical parameters in IgA nephropathy (IgAN) patients is still unknown.

Methods

A total of 46 human kidney biopsy specimens with IgAN were selected as observation group, specimens of normal renal cortex tissue that was not affected by the tumor from patients with renal carcinoma (n = 7) served as control. We investigated the relationship between HDAC6 and clinical parameters in IgAN.

Results

HDAC6 was highly expressed in human kidney biopsy specimens with IgAN compared with control group, while the number of acetyl histone H3 positive cells were significantly decreased. There was a statistical difference in the indexes of albumin, estimated glomerular filtration rate (eGFR), serum urea, serum creatinine, serum uric acid, β2-microglobulin, cystatin C, cholesterol, high-density lipoprotein, low-density lipoprotein, and HDAC6 positive area among the different Oxford Classification (p < 0.05). The expression of HDAC6 was different in various eGFR levels, the expression of HDAC6 increased with the decreasing of eGFR level, the expression of acetyl histone H3 decreased with the decreasing of eGFR level. In addition, the expression of HDAC6 positively correlated with Masson trichrome positive area, serum urea, serum creatinine, β2 macroglobulin, and cystatin C, while negatively correlated with eGFR and acetyl histone H3. Multivariate linear regression analysis demonstrated that eGFR and cystatin C were independently associated with HDAC6, respectively (p < 0.05).

Conclusions

These results suggested that high level of HDAC6 expression in IgAN is correlated with renal dysfunction.

Comprehensive analysis of IgA nephropathy expression profiles: identification of potential biomarkers and therapeutic agents

Background

IgA nephropathy (IgAN) is a kidney disease recognized by the presence of IgA antibody depositions in kidneys. The underlying mechanisms of this complicated disease are remained to be explored and still, there is an urgent need for the discovery of noninvasive biomarkers for its diagnosis. In this investigation, an integrative approach was applied to mRNA and miRNA expression profiles in PBMCs to discover a gene signature and novel potential targets/biomarkers in IgAN.

Methods

Datasets were selected from gene expression omnibus database. After quality control checking, two datasets were analyzed by Limma to identify differentially expressed genes/miRNAs (DEGs and DEmiRs). Following identification of DEmiR-target genes and data integration, intersecting mRNAs were subjected to different bioinformatic analyses. The intersecting mRNAs, DEmiRs, related transcription factors (from TRRUST database), and long-non coding RNAs (from LncTarD database) were used for the construction of a multilayer regulatory network via Cytoscape.

Result

“GSE25590” (miRNA) and “GSE73953” (mRNA) datasets were analyzed and after integration, 628 intersecting mRNAs were identified. The mRNAs were mainly associated with “Innate immune system”, “Apoptosis”, as well as “NGF signaling” pathways. A multilayer regulatory network was constructed and several hub-DEGs (Tp53, STAT3, Jun, etc.), DEmiRs (miR-124, let-7b, etc.), TFs (NF-kB, etc.), and lncRNAs (HOTAIR, etc.) were introduced as potential factors in the pathogenesis of IgAN.

Conclusion

Integration of two different expression datasets and construction of a multilayer regulatory network not only provided a deeper insight into the pathogenesis of IgAN, but also introduced several key molecules as potential therapeutic target/non-invasive biomarkers.

[Measurement of galactosyl-deficient IgA1 by the monoclonal antibody KM55 contributes to predicting patients with IgA nephropathy with high risk of long-term progression]

BACKGROUND AND OBJECTIVE

About 25% of patients with IgA nephropathy (IgAN) progress to stage 5 chronic kidney disease (CKD) after years of evolution. Various tools have been developed in recent years designed to predict which of the patients will had poorer outcomes. The value of circulating galactosyl-deficient IgA1 (Gd-IgA1) has been related to a worse evolution of IgAN in several studies. There are also some publications that relate higher APRIL values with a worse evolution. Recently, a new method has been developed that allows measuring the value of circulating Gd-IgA1 in a simpler way than those previously available. The objective of this study is to analyze the influence of circulating Gd-IgA1, measured by this method, on the progression of IgAN.

MATERIALS AND METHODS

Forty-nine patients with a diagnosis of IgAN demonstrated by renal biopsy were selected in our center, without having received prior immunosuppressive treatment, for whom frozen serum was available. The median follow-up was 4 years. Gd-IgA1 was measured by lectin-independent ELISA with the monoclonal antibody KM55 (IgA1 kit Cat. No. 30111694. IBL Int., Hamburg, Germany). Likewise, APRIL levels were also measured in these patients.

RESULTS

19 (38.8%) patients reached stage 5 CKD. The fourth quartile of circulating Gd-IgA1 was related to a higher cumulative risk of reaching stage 5 CKD in the Kaplan-Meier analysis (risk at the 5th year 39.4% vs. 24.3%, log rank p=0.019). The Gd-IgA1 value was related to an increased risk of CKD stage 5 (HR 1.147, 95% CI 1.035-1.270, p=0.009), regardless of glomerular filtration rate, proteinuria, the percentage of sclerosed glomeruli and the value of segmental sclerosis. We did not find significant differences in the APRIL values.

CONCLUSIONS

The value of circulating Gd-IgA1 measured by the monoclonal antibody KM55 is related to a worse evolution of patients with IgAN independently of other variables, so it could be included in the study of patients to improve the prediction of the risk of disease progression.

Validation of an international prediction model including the Oxford classification in Korean patients with IgA nephropathy

BACKGROUND

Recently, a new international risk prediction model including the Oxford classification was published which was validated in a large multi-ethnic cohort. Therefore, we aimed to validate this risk prediction model in Korean patients with IgA nephropathy.

METHODS

This retrospective cohort study was conducted with 545 patients who diagnosed IgA nephropathy with renal biopsy in three medical centers. The primary outcome was defined as a reduction in estimated glomerular filtration rate (eGFR) of >50% or incident end-stage renal disease (ESRD). Continuous net reclassification improvement (cNRI) and integrated discrimination improvement (IDI) were used to validate models.

RESULTS

During the median 3.6 years of follow-up period, 53 (9.7%) renal events occurred. In multivariable Cox regression model, M1 (hazard ratio [HR], 2.22; 95% confidence interval [CI], 1.02-4.82; p = .043), T1 (HR, 2.98; 95% CI, 1.39-6.39; p = .005) and T2 (HR, 4.80; 95% CI, 2.06-11.18; p < .001) lesions were associated with increased risk of renal outcome. When applied the international prediction model, the area under curve (AUC) for 5-year risk of renal outcome was 0.69, which was lower than previous validation and internally derived models. Moreover, cNRI and IDI analyses showed that discrimination and reclassification performance of the international model was inferior to the internally derived models.

CONCLUSION

The international risk prediction model for IgA nephropathy showed not as good performance in Korean patients as previous validation in other ethnic group. Further validation of risk prediction model is needed for Korean patients with IgA nephropathy.

Towards the best kidney failure prediction tool: a systematic review and selection aid

Background

Prediction tools that identify chronic kidney disease (CKD) patients at a high risk of developing kidney failure have the potential for great clinical value, but limited uptake. The aim of the current study is to systematically review all available models predicting kidney failure in CKD patients, organize empirical evidence on their validity and ultimately provide guidance in the interpretation and uptake of these tools.

Methods

PubMed and EMBASE were searched for relevant articles. Titles, abstracts and full-text articles were sequentially screened for inclusion by two independent researchers. Data on study design, model development and performance were extracted. The risk of bias and clinical usefulness were assessed and combined in order to provide recommendations on which models to use.

Results

Of 2183 screened studies, a total of 42 studies were included in the current review. Most studies showed high discriminatory capacity and the included predictors had large overlap. Overall, the risk of bias was high. Slightly less than half the studies (48%) presented enough detail for the use of their prediction tool in practice and few models were externally validated.

Conclusions

The current systematic review may be used as a tool to select the most appropriate and robust prognostic model for various settings. Although some models showed great potential, many lacked clinical relevance due to being developed in a prevalent patient population with a wide range of disease severity. Future research efforts should focus on external validation and impact assessment in clinically relevant patient populations.

The Association between Serum Hemoglobin and Renal Prognosis of IgA Nephropathy

Immunoglobin A (IgA) nephropathy causes chronic kidney disease worldwide. Therefore, identifying risk factors associated with the progression of IgA nephropathy is crucial. Anemia is a common complication of chronic kidney disease; however, few studies have investigated the effect of serum hemoglobin on the renal prognosis of IgA nephropathy. This study aimed to determine the effect of serum hemoglobin on the progression of IgA nephropathy. We retrospectively analyzed 4326 patients with biopsy-proven IgA nephropathy. We evaluated the effect of serum hemoglobin on IgA nephropathy progression using Kaplan-Meier survival analyses, the log-rank test, and the Cox proportional hazards model. The primary end-point was progression of IgA nephropathy, defined as dialysis initiation or kidney transplantation. Serum hemoglobin showed a nonlinear relationship with the progression of IgA nephropathy. The Cox proportional hazards model showed that the risk of progression of IgA nephropathy decreased 0.87 times for every 1.0 g/dL increase in serum hemoglobin. In subgroup analyses, reduced serum hemoglobin was an independent risk factor for IgA nephropathy progression only in women. There was no statistically significant interaction of serum hemoglobin between men and women (P _interaction = 0.177). Results of Sensitivity analysis were robust and consistent. Serum hemoglobin at diagnosis was an independent predictor for IgA nephropathy progression.

Hypoxia-Inducible Factor-Proline Hydroxylase Inhibitor in the Treatment of Renal Anemia

Background

Anemia is a common complication in CKD patients. Despite the use of iron and erythropoietin-stimulating agents, the control rate of anemia in CKD is not satisfying. Novel drugs are needed for anemia correction.

Summary

HIF-PHI, hypoxia-inducible factor-proline hydroxylase inhibitor, a novel class of therapeutic agents, has been developed to treat anemia in CKD patients. Its main effects comprised boosting EPO production, enhancing iron utilization, and suppressing hepcidin production. Several stage 2 and stage 3 clinical trials have been run to test its efficacy and safety in both nondialysis and dialysis patients, of which the results are very encouraging. Here, we summarize the mechanism, clinical applications, and clinical trials of HIF-PHI in treating renal anemia in order to give an overview of the new drug in clinical practices.

Key Messages

HIF-PHI is a novel therapeutic agent of treating renal anemia in CKD patients. It is quite effective in improving anemia, which is unaffected by inflammation. Besides, it may ameliorate lipid metabolism as well. Furthermore, the oral form may improve patients' compliances with treatment. Thus, it may be a good alternative of anemia correction in CKD patients.

Repeat renal biopsy improves the Oxford classification-based prediction of immunoglobulin A nephropathy outcome

BACKGROUND

The prognosis of IgA nephropathy (IgAN) is very heterogeneous. Predicting the nature and the rate of the disease progression is crucial for refining patient treatment. The aim of this study was to evaluate the prognostic impact of an Oxford classification-based repeat kidney tissue evaluation to predict end-stage renal disease (ESRD).

METHODS

Patients with biopsy-proven primary IgAN who underwent two renal biopsies at our centre were analyzed retrospectively. Renal biopsies were scored by two pathologists blinded to the clinical data and according to the updated Oxford classification. Cox models were generated to evaluate the prognostic impact considering the Oxford classification elementary lesions from the first (Model 1) or the second (Model 2) biopsy, adjusted on clinical data at time of reevaluation. The prognostic impacts of the dynamic evolution of each elementary lesion between biopsies were also assessed through univariate and multivariate evaluation.

RESULTS

A total of 168 adult patients were included, with a median follow-up duration of 18 (range 11-24) years. The second biopsy was performed either systematically (n = 112) of for-cause (n = 56), after a median time of 5.4 years. The prognostic performances of Model 2 (second biopsy) were significantly better than Model 1 (first biopsy, analysis of deviance P < 0.0001). The dynamic changes of C and T lesions were significantly associated with the progression toward ESRD after adjustment on variables from Model 2.

CONCLUSION

Both static and dynamic Oxford-based histological evaluation offered by a repeat biopsy improves the prediction of ESRD in patients with IgAN.

Evidences of histologic thrombotic microangiopathy and the impact in renal outcomes of patients with IgA nephropathy

INTRODUCTION

IgA nephropathy (IgAN) is the most common primary glomerulopathy worldwide. According to the Oxford Classification, changes in the kidney vascular compartment are not related with worse outcomes. This paper aims to assess the impact of thrombotic microangiopathy (TMA) in the outcomes of Brazilian patients with IgAN.

MATERIALS AND METHODS

Analysis of clinical data and kidney biopsy findings from patients with IgAN to assess the impact of TMA on renal outcomes.

RESULTS

The majority of the 118 patients included were females (54.3%); mean age of 33 years (25;43); hypertension and hematuria were observed in 67.8% and 89.8%, respectively. Median creatinine: 1.45mg/dL; eGFR: 48.8ml/min/1.73m2; 24-hour proteinuria: 2.01g; low serum C3: 12.5%. Regarding to Oxford Classification: M1: 76.3%; E1: 35.6%; S1: 70.3%; T1/T2: 38.3%; C1/C2: 28.8%. Average follow-up: 65 months. Histologic evidence of TMA were detected in 21 (17.8%) patients and those ones presented more frequently hypertension (100% vs. 61%, p <0.0001), hematuria (100% vs 87.6%, p = 0.0001), worse creatinine levels (3.8 vs. 1.38 mg/dL, p = 0.0001), eGFR (18 vs. 60 ml/min/1.73m2), p = 0.0001), low serum C3 (28.5% vs. 10.4%, p = 0.003), lower hemoglobin levels (10.6 vs. 12.7g/dL, p<0.001) and platelet counts (207,000 vs. 267,000, p = 0.001). Biopsy findings of individuals with TMA revealed only greater proportions of E1 (68% vs. 32%, p = 0.002). Individuals with TMA were followed for less time (7 vs. 65 months, p<0.0001) since they progressed more frequently to chronic kidney disease (CKD) requiring kidney replacement therapy (KRT) (71.4% vs. 21,6%, p<0.0001). Male sex, T1/T2, and TMA were independently associated with progression to CKD-KRT.

CONCLUSIONS

In this study patients with TMA had worse clinical manifestations and outcomes. In terms of histologic evidence, E1 distinguished patients with TMA from other patients. Further studies are necessary to analyze the impact of vascular lesions on IgAN prognosis.

Increased Lifetime Risk of ESRD in Familial IgA Nephropathy

Introduction

Familial IgA nephropathy (IgAN) has been widely reported. However, its clinicohistologic characteristics and long-term prognosis are not clear.

Methods

A total of 348 familial IgAN cases from 167 independent families were recruited and their clinicohistologic characteristics as well as lifetime risk of end-stage renal disease (ESRD) were compared to 1116 sporadic IgAN patients from the same geographic region.

Results

Of all familial IgAN patients, 60 (17%) came from 32 single-generation (SG; all affected individuals are siblings) families, whereas 286 (82%) came from 134 multiple-generation (MG; affected individuals were present in at least 2 consecutive generations) families. The lifetime ESRD risk was significantly higher in familial patients than sporadic ones after adjusting by gender (hazard ratio [HR]=1.40, 95% confidence interval [CI]: 1.12–1.74, P = 0.004), with 5 years younger in median ESRD age (60 years vs. 65 years in familial and sporadic cases separately). Interestingly, among familial patients, we found cases from SG families (vs. MG families: HR = 2.62, 95% CI: 1.59–4.31, P < 0.001) or with early onset (onset age <30 years) (vs. late onset: HR = 4.79, 95% CI: 3.16–7.26, P < 0.001) had higher lifetime ESRD risk. Furthermore, among sporadic patients, men had lower estimated glomerular filtration rate (eGFR), higher urine protein, higher Oxford T score, and higher risk for life span ESRD compared with women (male vs. female, 25% vs. 17%, P = 0.003) whereas these gender differences were not seen in familial patients.

Conclusion

Familial IgAN cases had poorer renal outcomes and less gender differences compared with sporadic cases. These findings provide evidence that familial disease represent a distinct subtype of more progressive IgAN. Early diagnosis could improve the prognosis of cases with familial IgAN.

How to optimize the design and implementation of risk prediction tools: focus group with patients with IgA nephropathy

Background

IgA nephropathy (IgAN) is a common type of chronic immune-mediated kidney disease with variable risk of progression to end-stage kidney disease. Risk stratification helps clinicians weight the potential risks and benefits of immunosuppressive therapy for individual patients, and can inform patient-centred communication. No prior research examined barriers of risk predication tools (RPT) specific to IgAN. The purpose of this study was to explore determinants (facilitators, barriers) of RPT use from the patient perspective.

Methods

We conducted a single focus group with English-speaking adults aged 18 or older with biopsy-proven IgAN. We asked about how they would use an IgAN RPT, and how to improve its design and implementation. We analyzed the transcript using constant comparison to inductively derive themes, and complied with qualitative research reporting criteria.

Results

The 5 participants were Caucasian men who varied in age from 35 to 55. The glomerular filtration rate ranged from 29 to 71 mL/min/1.73m², and proteinuria ranged from 0.36 to 1.41 g/d. Participants identified both benefits and harms of the risk score. They said physicians should first ask patients for permission to use it. To make it more useful, participants offered suggestions to enhance RTP design: visual display, information on how to interpret the risk score, risk categories, health implications, modifiable risk factors, multiple scenarios, and comparison with similar patients. They offered additional suggestions to enhance RPT implementation: it should not replace patient-provider discussion, it should be accompanied by self-management education so that patients can take an active role in their health. Participants appreciated information from members of the multidisciplinary team in addition to physicians. Participants also said that physicians should monitor patient emotions or concerns on an ongoing basis.

Conclusions

Patients with IgAN identified numerous ways to enhance the design and use of an RPT. Others could use this information to design and implement RPTs for patients with other conditions, but should employ user-centred design to develop RPTs that address patient preferences.

The Association of Low Hemoglobin Levels with IgA Nephropathy Progression: A Two-Center Cohort Study of 1,828 Cases

AIM

To investigate the relationship between hemoglobin levels and the progression of IgA nephropathy (IgAN).

METHODS

In a two-center cohort of 1,828 cases with biopsy-proven IgAN, we examined the association of hemoglobin levels with the primary outcome of a composite of all-cause mortality or kidney failure defined as a 40% decline in eGFR, or ESKD (defined as eGFR <15 mL/min/1.73 m2 or need for kidney replacement therapy including hemodialysis, peritoneal dialysis, or kidney transplantation), or the outcome of kidney failure, assessed using Cox and logistic regression models, respectively, with adjustment for confounders.

RESULTS

At baseline, mean age, eGFR, and hemoglobin levels were 33.75 ± 11.03 years, 99.70 ± 30.40 mL/min/1.73 m2, and 123.47 ± 18.36 g/L, respectively. During a median of approximately 7-year follow-up, 183 cases reached the composite outcome. After adjustment for demographic and IgAN-specific covariates and treatments, a lower quartile of hemoglobin was nonlinearly associated with an increased risk of the primary outcome or kidney failure in the Cox proportional hazards models (primary outcome: HR for quartile 3 vs. 4, 1.37; 95% CI, 0.83-2.25; HR for quartile 2 vs. 4, 1.18; 95% CI, 0.68-2.07; HR for quartile 1 vs. 4, 1.91; 95% CI, 1.15-3.17; kidney failure: HR for quartile 3 vs. 4, 1.39; 95% CI, 0.84-2.31; HR for quartile 2 vs. 4, 1.20; 95% CI, 0.68-2.11; HR for quartile 1 vs. 4, 1.83; 95% CI, 1.09-3.07) in the fully adjusted model. Then, hemoglobin levels were transformed to a binary variable for fitting the model according to the criteria for anemia of 110 g/L in the women and 120 g/L in men in China. The participants in the anemia group had an increased risk of developing outcomes compared with the nonanemia group in both genders (primary outcome: male: HR, 1.64; 95% CI, 1.01-2.68; female: HR, 1.68; 95% CI, 1.02-2.76; kidney failure: male: HR, 1.60; 95% CI, 0.97-2.64; female: HR, 1.58; 95% CI, 0.95-2.61) in the fully adjusted model.

CONCLUSIONS

A low level of hemoglobin was nonlinearly associated with IgAN progression. The anemic IgAN patients presented a higher risk of developing poor outcomes compared with the nonanemic patients.

External Validation of the International IgA Nephropathy Prediction Tool

BACKGROUND AND OBJECTIVES

The International IgA Nephropathy Network recently developed and externally validated two models to predict the risk of progression of IgA nephropathy: full models without and with race. This study sought to externally validate the International IgA Nephropathy Prediction Tool in a large, independent, and contemporary cohort in China.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We included 1373 patients with biopsy-confirmed primary IgA nephropathy from The First Affiliated Hospital of Zhengzhou University from January 2012 to May 2018 and calculated predicted risks for each patient. The outcomes of interest were a 50% decline in eGFR or kidney failure. We assessed the performance of both models using discrimination (concordance statistics and Kaplan-Meier curves between subgroups), calibration (calibration plots), reclassification (net reclassification improvement and integrated discrimination improvement), and clinical utility (decision curve analysis).

RESULTS

The median follow-up was 29 months (interquartile range, 21-43 months; range, 1-95 months), and 186 (14%) patients reached the kidney outcomes of interest. Both models showed excellent discrimination (concordance statistics >0.85 and well separated survival curves). Overall, the full model without race generally underestimated the risk of primary outcome, whereas the full model with race was well calibrated for predicting 5-year risk. Compared with the full model without race, the full model with race had significant improvement in reclassification, as assessed by the net reclassification improvement (0.49; 95% confidence interval, 0.41 to 0.59) and integrated discrimination improvement (0.06; 95% confidence interval, 0.04 to 0.08). Decision curve analysis showed that both full models had a higher net benefit than default strategies, and the model with race performed better.

CONCLUSIONS

In this study, both full models demonstrated remarkable discrimination, acceptable calibration, and satisfactory clinical utility. The relatively short follow-up time may have limited the validation of these models.

Clinical, pathological characteristics and outcomes of immunoglobulin A nephropathy patients with different ages

AIM

To determine the clinical and pathological differences in immunoglobulin A (IgA) nephropathy (IgAN) with different ages, and to determine whether age is a risk factor for progression of IgAN.

METHODS

This was a single centre retrospective cohort study. Patients with biopsy-diagnosed primary IgAN were stratified into three groups: young-aged (14-29 years), middle-aged (30-49 years) and older-age (≥50 years). The primary outcome was end-stage renal disease (estimated glomerular filtration rate [eGFR] <15 mL/min/1.73 m² , dialysis or renal transplantation) or doubling of the baseline serum creatinine.

RESULTS

A total of 981 patients were enrolled, including 65 (6.6%) patients in older-age group, 517 (52.7%) in middle-aged group and 399 (40.7%) in young-aged group. The older-age group had significantly higher levels of serum IgA, cholesterol, triglycerides and creatinine, and a reduced eGFR. In contrast to the young adults who had a higher percentage of crescent formation in glomeruli, the older-aged patients had more severe chronic pathological changes including global glomerulosclerosis and vascular lesions (p < .01). The cumulative renal survival in the older-age group was slightly shorter than that in the young adult or middle-aged group, but not achieving significant (p > .05). The 3- and 5-year renal survival rates were similar among the three groups. A multivariate Cox regression analysis showed that age was not an independent predictor of an unfavourable prognosis.

CONCLUSION

The IgAN patients with aged 50 years or older had different clinical pathological changes as compared with younger patients. However, aging was not found as an independently predictor of renal progression of IgAN. Prolonged follow up is necessary to confirm this trend.

Evaluating a New International Risk-Prediction Tool in IgA Nephropathy

IMPORTANCE

Although IgA nephropathy (IgAN) is the most common glomerulonephritis in the world, there is no validated tool to predict disease progression. This limits patient-specific risk stratification and treatment decisions, clinical trial recruitment, and biomarker validation.

OBJECTIVE

To derive and externally validate a prediction model for disease progression in IgAN that can be applied at the time of kidney biopsy in multiple ethnic groups worldwide.

DESIGN, SETTING, AND PARTICIPANTS

We derived and externally validated a prediction model using clinical and histologic risk factors that are readily available in clinical practice. Large, multi-ethnic cohorts of adults with biopsy-proven IgAN were included from Europe, North America, China, and Japan.

MAIN OUTCOMES AND MEASURES

Cox proportional hazards models were used to analyze the risk of a 50% decline in estimated glomerular filtration rate (eGFR) or end-stage kidney disease, and were evaluated using the R2D measure, Akaike information criterion (AIC), C statistic, continuous net reclassification improvement (NRI), integrated discrimination improvement (IDI), and calibration plots.

RESULTS

The study included 3927 patients; mean age, 35.4 (interquartile range, 28.0-45.4) years; and 2173 (55.3%) were men. The following prediction models were created in a derivation cohort of 2781 patients: a clinical model that included eGFR, blood pressure, and proteinuria at biopsy; and 2 full models that also contained the MEST histologic score, age, medication use, and either racial/ethnic characteristics (white, Japanese, or Chinese) or no racial/ethnic characteristics, to allow application in other ethnic groups. Compared with the clinical model, the full models with and without race/ethnicity had better R2D (26.3% and 25.3%, respectively, vs 20.3%) and AIC (6338 and 6379, respectively, vs 6485), significant increases in C statistic from 0.78 to 0.82 and 0.81, respectively (ΔC, 0.04; 95% CI, 0.03-0.04 and ΔC, 0.03; 95% CI, 0.02-0.03, respectively), and significant improvement in reclassification as assessed by the NRI (0.18; 95% CI, 0.07-0.29 and 0.51; 95% CI, 0.39-0.62, respectively) and IDI (0.07; 95% CI, 0.06-0.08 and 0.06; 95% CI, 0.05-0.06, respectively). External validation was performed in a cohort of 1146 patients. For both full models, the C statistics (0.82; 95% CI, 0.81-0.83 with race/ethnicity; 0.81; 95% CI, 0.80-0.82 without race/ethnicity) and R2D (both 35.3%) were similar or better than in the validation cohort, with excellent calibration.

CONCLUSIONS AND RELEVANCE

In this study, the 2 full prediction models were shown to be accurate and validated methods for predicting disease progression and patient risk stratification in IgAN in multi-ethnic cohorts, with additional applications to clinical trial design and biomarker research.

Random forest can accurately predict the development of end-stage renal disease in immunoglobulin a nephropathy patients

Background

IgA nephropathy (IgAN) is the most common glomerulonephritis worldwide and up to 40% will develop end-stage renal disease (ESRD) within 20 years. However, predicting which patients will progress to ESRD is difficult. The purpose of this study was to develop a predictive model which could accurately predict whether IgAN patients would progress to ESRD.

Methods

Six machine learning algorithms were used to predict whether IgAN patients would progress to ESRD: logistic regression, random forest, support vector machine (SVM), decision tree, artificial neural network (ANN), k nearest neighbors (KNN). Nineteen demographic, clinical, pathologic and treatment parameters were used as input for the prediction models.

Results

Random forest is best able to predict progression to ESRD. The model had accuracy of 93.97% and sensitivity and specificity of 80.60% and 95.27%, respectively.

Conclusions

Machine learning algorithms can effectively predict which patients with IgA nephropathy will progress to end stage renal disease.

A Rare Genetic Defect of MBL2 Increased the Risk for Progression of IgA Nephropathy

The aim of this study was to investigate the association between lectin pathway-related genetic variations and progression in IgA nephropathy. Biopsy-proven IgAN patients with eGFR ≥15 ml/min/1.73 m2 at baseline and a minimum follow-up of 12-months were enrolled. A total of 1,007 patients and 121 healthy controls were enrolled from two Chinese renal centers. The discovery cohort consisted of 606 patients, and the validation cohort consisted of 401 patients. First, promoters, all exons and their boundary regions of MBL2 and FCN2 were sequenced in 50 patients, and then 37 variations were identified. Of these variations, 7 expression-associated variations were selected and genotyped in the whole discovery cohort. We found that rs1800450 in MBL2 and rs7851696 in FCN2 were associated with an increased risk for ESRD as well as serum MBL or L-ficolin levels. However, only rs1800450 was successively validated for its association with ESRD (HR, 15.91; 3.27-77.34; P = 0.001) in the fully adjusted model in the validation cohort. In addition, 2.7% of patients, and 2.5% of healthy controls carried rs1800450-AA. IgAN patients with rs1800450-AA lacked expression of MBL in both serum and renal tissue and had more severe tubulointerstitial damage. Furthermore, a combined effect of rs1800450-AA with a previously reported clinical risk score was observed in which patients with both a high clinical risk score (≥1%) and rs1800450-AA had a strikingly increased 10-years ESRD risk by 37.1-fold (7.17 to 192.13-fold). In summary, IgAN patients carrying MBL2 rs1800450-AA have a high risk for renal function deterioration, probably due to inactivation of the complement MBL pathway.

An update on predicting renal progression in IgA nephropathy

PURPOSE OF REVIEW

Immunoglobulin A (IgA) nephropathy (IgAN) is a heterogeneous disease, and predicting individual patient risk of renal progression is challenging. Recent studies provide new evidence regarding the use of clinical, histologic, and biomarker predictors of renal outcome in IgAN.

RECENT FINDINGS

A meta-analysis of clinical trials demonstrated that early change in proteinuria is a valid surrogate outcome measure for longer term decline in renal function, which supports the use of proteinuria to dynamically re-evaluate patient prognosis over time. The MEST histologic classification has been further validated in a large European cohort. An international multiethnic observational study demonstrated that crescents are independently associated with renal outcome, and as a result a crescent score (<25% versus >25% of glomeruli) has been added to MEST. Proteinuria, estimated glomerular filtration rate (GFR), and blood pressure at the time of biopsy can be used to accurately predict prognosis when combined with MEST, instead of using 2 years of follow-up data. Currently, no available risk prediction model that combines clinical and histologic predictors has been sufficiently validated for routine use. There are multiple biomarkers that have been studied in IgAN, however none have been externally validated and shown to improve prediction beyond clinical and histologic risk factors.

SUMMARY

Proteinuria, estimated GFR, blood pressure, and the MEST-C score are the most readily available risk factors to predict renal prognosis in IgAN. Future research is required to develop and validate methods of integrating these risk factors together to accurately risk stratify individual patients, and provide the framework for evaluating biomarkers capable of further improving risk prediction.

IgA Nephropathy Susceptibility Loci and Disease Progression

BACKGROUND AND OBJECTIVES

At least 20 susceptibility loci of IgA nephropathy have been identified by genome-wide association studies to date. Whether these loci were associated with disease progression is unclear.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We enrolled 613 adult patients with IgA nephropathy for a follow-up of ≥12 months. All 20 IgA nephropathy susceptibility loci were selected and their tag single nucleotide polymorphisms (SNPs) were genotyped. After strict quality control, 16 SNPs and 517 patients with IgA nephropathy were eligible for subsequent analysis. Progression was defined as ESKD or 50% decrease in eGFR. A stepwise Cox regression analysis of all SNPs on Akaike information criterion was performed to select the best model.

RESULTS

A four-SNP model, rs11150612 (ITGAM-ITGAX), rs7634389 (ST6GAL1), rs2412971 (HORMAD2), and rs2856717 (HLA-DQ/DR), was selected as the best predictive model. The genetic risk score calculated on the basis of the four SNPs was independently associated with disease progression before (hazard ratio [HR], 1.65; 95% confidence interval [95% CI], 1.29 to 2.12) and after adjustment by a recently reported clinical model (HR, 1.29; 95% CI, 1.03 to 1.62) or clinical-pathologic model (HR, 1.35; 95% CI, 1.03 to 1.77). Compared with low genetic risk, patients with middle genetic risk had a 2.12-fold (95% CI, 1.33 to 3.40) increase of progression risk, whereas patients with high genetic risk had 3.61-fold (95% CI, 2.00 to 6.52) progression risk increase. In addition, incorporation of genetic risk score could potentially increase discrimination of the clinical model (c-statistic increase from 0.83 to 0.86) or the clinical-pathologic model (c-statistic increase from 0.82 to 0.85) in predicting 5-year progression risk.

CONCLUSIONS

The four-SNP genetic risk score was independently associated with IgA nephropathy progression and could enhance the performance of clinical and clinical-pathologic risk models.