Glomerular transcriptomics predicts long term outcome and identifies therapeutic strategies for patients with assumed benign IgA nephropathy

Some patients diagnosed with benign IgA nephropathy (IgAN) develop a progressive clinical course, not predictable by known clinical or histopathological parameters. To assess if gene expression can differentiate between progressors and non-progressors with assumed benign IgAN, we tested microdissected glomeruli from archival kidney biopsy sections from adult patients with stable clinical remission (21 non-progressors) or from 15 patients that had undergone clinical progression within a 25-year time frame. Based on 1 240 differentially expressed genes from patients with suitable sequencing results, we identified eight IgAN progressor and nine non-progressor genes using a two-component classifier. These genes, including APOL5 and ZXDC, predicted disease progression with 88% accuracy, 75% sensitivity and 100% specificity on average 21.6 years before progressive disease was clinically documented. APOL lipoproteins are associated with inflammation, autophagy and kidney disease while ZXDC is a zinc-finger transcription factor modulating adaptive immunity. Ten genes from our transcriptomics data overlapped with an external genome wide association study dataset, although the gene set enrichment test was not statistically significant. We also identified 45 drug targets in the DrugBank database, including angiotensinogen, a target of sparsentan (dual antagonist of the endothelin type A receptor and the angiotensin II type 1 receptor) currently investigated for IgAN treatment. Two validation cohorts were used for substantiating key results, one by immunohistochemistry and the other by nCounter technology. Thus, glomerular mRNA sequencing from diagnostic kidney biopsies from patients with assumed benign IgAN can differentiate between future progressors and non-progressors at the time of diagnosis.

Epstein-Barr in a Patient Presenting with Right Upper Quadrant Pain: A Case Report from the Emergency Department

BACKGROUND

Right upper quadrant abdominal pain and elevated cholestasis blood tests are usually associated with bacterial calculous cholecystitis. However, viral infections, such as Epstein-Barr virus (EBV) can also manifest with a similar clinical picture and is an important differential diagnosis.

CASE REPORT

This case report discusses a young woman presenting to the emergency department with acute right upper quadrant abdominal pain. The initial assessment revealed a positive Murphy's sign, elevated white blood count, and a cholestatic pattern on liver function tests, leading one to suspect bacterial calculous cholecystitis and initiating antibiotic therapy. However, clinical examination also revealed tonsillar exudates and differential white blood cell count revealed monocytosis and lymphocytosis rather than a high neutrophil count. The patient tested positive for EBV. Furthermore, ultrasound and magnetic resonance imaging revealed gallbladder wall edema with no gallstones, leading one to conclude that the clinical manifestation and laboratory results were due to an EBV infection. Antibiotic therapy was ceased and the patient did not require surgical intervention. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Calculous bacterial cholecystitis usually entails antibiotic therapy and cholecystectomy. It is important to be aware of the differential diagnosis of EBV, as it usually does not require either of these and resolves spontaneously.

Use of corticosteroids in Norwegian patients with immunoglobulin a nephropathy progressing to end-stage kidney disease: a retrospective cohort study

BACKGROUND

Despite several clinical trials, the use of corticosteroid therapy for treating immunoglobulin A nephropathy (IgAN) remains controversial. We aimed to describe the use of corticosteroid therapy combined with supportive therapy in Norwegian patients with IgAN who had progressed to end-stage kidney disease.

METHODS

We conducted a retrospective cohort study using data from the Norwegian Renal Registry. Overall, 143 patients with primary IgAN who progressed to end-stage kidney disease were divided into two groups: the corticosteroid group, who had been treated with corticosteroids and supportive therapy, and the non-corticosteroid group, which had underwent only supportive therapy. The kidney function, time to end-stage kidney disease, and adverse effects were described. The observation period lasted from the diagnostic kidney biopsy until the initiation of kidney replacement therapy.

RESULTS

Of the 143 included patients, 103 underwent supportive therapy alone, and 40 were treated with corticosteroids. Most patients (94%) were treated with renin-angiotensin-system blockade, and all patients reached end-stage kidney disease after a median of 5 years (interquartile range; 2-9 years). Time from diagnosis until end-stage kidney disease was similar in the two study groups (p = 0.98). During 6 months of corticosteroid therapy, median eGFR declined from 21 (interquartile range; 13-46) mL/min/1.73 m2 to 20 (interquartile range; 12-40) mL/min/1.73 m2, and median proteinuria decreased from 5.5 g/24 h to 3.0 g/24 h. Most patients (87.5%) treated with corticosteroids reported adverse events. In our linear regression analysis investigating the time to ESKD, we found that age (β = -0.079, p = 0.008) and proteinuria at diagnosis (β = -0.50, p = 0.01) exhibited statistically significant associations with a delay in the progression to ESKD.

CONCLUSIONS

In this cohort of Norwegian patients with IgAN, corticosteroid therapy did not affect the time from diagnosis until end-stage kidney disease among a cohort of patients who all reached end-stage kidney disease. The treatment was also associated with adverse effects.

Long-term follow-up of IgA nephropathy: clinicopathological features and predictors of outcomes

Background

The establishment of the Oxford classification and newly developed prediction models have improved the prognostic information for immunoglobulin A nephropathy (IgAN). Considering new treatment options, optimizing prognostic information and improving existing prediction models are favorable.

Methods

We used random forest survival analysis to select possible predictors of end-stage kidney disease among 37 candidate variables in a cohort of 232 patients with biopsy-proven IgAN retrieved from the Norwegian Kidney Biopsy Registry. The predictive value of variables with relative importance >5% was assessed using concordance statistics and the Akaike information criterion. Pearson's correlation coefficient was used to identify correlations between the selected variables.

Results

The median follow-up period was 13.7 years. An isolated analysis of histological variables identified six variables with relative importance >5%: T %, segmental glomerular sclerosis without characteristics associated with other subtypes (not otherwise specified, NOS), normal glomeruli, global sclerotic glomeruli, segmental adherence and perihilar glomerular sclerosis. When histopathological and clinical variables were combined, estimated glomerular filtration rate (eGFR), proteinuria and serum albumin were added to the list. T % showed a better prognostic value than tubular atrophy/interstitial fibrosis (T) lesions with C-indices at 0.74 and 0.67 and was highly correlated with eGFR. Analysis of the subtypes of segmental glomerulosclerosis (S) lesions revealed that NOS and perihilar glomerular sclerosis were associated with adverse outcomes.

Conclusions

Reporting T lesions as a continuous variable, normal glomeruli and subtypes of S lesions could provide clinicians with additional prognostic information and contribute to the improved performance of the Oxford classification and prognostic tools.

The diagnostic utility of microscopic quality assessment of sputum samples in the era of rapid syndromic PCR testing

This prospective study assessed the value of initial microscopy evaluation of sputum samples submitted for rapid syndromic PCR-based testing. Bacterial detections by the BioFire FilmArray Pneumonia Panel plus in 126 high- and 108 low-quality sputum samples, based on initial microscopy evaluation in samples from patients with lower respiratory tract infections were compared. We found that high-quality samples had a higher proportion of bacterial detections compared to low-quality samples (P = 0.013). This included a higher proportion of detections of bacteria deemed clinically relevant by predefined criteria (70% and 55%, P = 0.016), as well as a higher proportion of detections of Haemophilus influenzae (36% and 20%, P = 0.010). High-quality samples also had more detections of bacteria with high semi-quantitative values. The study found no significant difference between high- and low-quality samples in the proportions of samples with a single species of bacteria detected, samples with a bacteria treated by the clinician, samples with detection of a proven etiology of community-acquired pneumonia by predefined criteria, the number of bacterial species detected, or the detection of Streptococcus pneumoniae, Moraxella catarrhalis, or Staphylococcus aureus. The results showed that 40% (95% CI 35%-47%) of the bacterial detections would have been missed if only high-quality samples were analyzed. This included 41% (27%-56%) of detections of S. pneumoniae, 33% (23%-45%) of detections of H. influenzae, 42% (28%-58%) of detections of S. aureus, and 37% (23%-54%) of detections of M. catarrhalis. These findings suggest that all sputum samples submitted for rapid syndromic PCR testing should be analyzed, regardless of initial microscopy quality assessment. (This study has been registered at ClinicalTrials.gov under registration no. NCT04660084.) IMPORTANCE Microscopic quality assessment of sputum samples was originally designed for sputum culture, and its applicability in today's workflow, which includes syndromic PCR testing, may differ. Addressing this crucial gap, our study emphasizes the need to optimize the use and workflow of syndromic PCR panels, like the BioFire FilmArray Pneumonia plus (FAP plus), in microbiology laboratories. These advanced PCR-based tests offer rapid and comprehensive pathogen detection for respiratory infections, yet their full potential remains uncertain. By comparing bacterial detections in high- and low-quality sputum samples, we underscore the importance of including low-quality samples in testing. Our findings reveal a significant proportion of potentially clinically relevant bacterial detections that would have been missed if only high-quality samples were analyzed. These insights support the efficient implementation of syndromic PCR panels, ultimately enhancing patient care and outcomes.

Growth Differentiation Factor 15: A Prognostic Marker in Patients with Acute Chest Pain without Acute Myocardial Infarction

BACKGROUND

Acute chest pain is associated with an increased risk of death and cardiovascular events even when acute myocardial infarction (AMI) has been excluded. Growth differentiation factor-15 (GDF-15) is a strong prognostic marker in patients with acute chest pain and AMI, but the prognostic value in patients without AMI is uncertain. This study sought to investigate the ability of GDF-15 to predict long-term prognosis in patients presenting with acute chest pain without AMI.

METHODS

In total, 1320 patients admitted with acute chest pain without AMI were followed for a median of 1523 days (range: 4 to 2208 days). The primary end point was all-cause mortality. Secondary end points included cardiovascular (CV) death, future AMI, heart failure hospitalization, and new-onset atrial fibrillation (AF).

RESULTS

Higher concentrations of GDF-15 were associated with increased risk of death from all causes (median concentration in non-survivors vs survivors: 2124 pg/mL vs 852 pg/mL, P < 0.001), and all secondary end points. By multivariable Cox regression, GDF-15 concentration ≥4th quartile (compared to <4th quartile) remained an independent predictor of all-cause death (adjusted hazard ratio (HR): 2.75; 95% CI, 1.69-4.45, P < 0.001), CV death (adjusted HR: 3.74; 95% CI, 1.31-10.63, P = 0.013), and heart failure hospitalization (adjusted HR: 2.60; 95% CI, 1.11-6.06, P = 0.027). Adding GDF-15 to a model consisting of established risk factors and high-sensitivity cardiac troponin T (hs-cTnT) led to a significant increase in C-statistics for prediction of all-cause mortality.

CONCLUSIONS

Higher concentrations of GDF-15 were associated with increased risk of mortality from all causes and risk of future CV events.

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.

Implementing a new emergency medical triage tool in one health region in Norway: some lessons learned

BACKGROUND

Acutely sick or injured patients depend on ambulance and emergency department personnel performing an accurate initial assessment and prioritisation (triage) to effectively identify patients in need of immediate treatment. Triage also ensures that each patient receives fair initial assessment. To improve the patient safety, quality of care, and communication about a patient's medical condition, we implemented a new triage tool (the South African Triage Scale Norway (SATS-N) in all the ambulance services and emergency departments in one health region in Norway. This article describes the lessons we learnt during this implementation process.

METHODS

The main framework in this quality improvement (QI) work was the plan-do-study-act cycle. Additional process sources were 'The Institute for Healthcare Improvement Model for improvement' and the Norwegian Patient Safety Programme.

RESULTS

Based on the QI process as a whole, we defined subjects influencing this work to be successful, such as identifying areas for improvement, establishing multidisciplinary teams, coaching, implementing measurements and securing sustainability. After these subjects were connected to the relevant challenges and desired effects, we described the lessons we learnt during this comprehensive QI process.

CONCLUSION

We learnt the importance of following a structured framework for QI process during the implementation of the SATS-N triage tool. Furthermore, securing anchoring at all levels, from the managements to the medical professionals in direct patient-orientated work, was relevant important. Moreover, establishing multidisciplinary teams with ambulance personnel, emergency department nurses and doctors with various medical specialties provided ownership to the participants. Meanwhile, coaching provided necessary security for the staff directly involved in caring for patients. Keeping the spirit and perseverance high were important factors in completing the implementation. Establishment of the regional network group was found to be important for sustainability and further improvements.

MO447: Glomerular Transcriptomics in IGA Nephropathy Differentiates Between Disease Progression and Stability in Low-Risk Patients After Prolonged Follow-Up

BACKGROUND AND AIMS

IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. We have previously shown that patients with assumed benign IgAN can develop progressive kidney failure, including end-stage kidney disease, after a sufficiently long follow-up period [1]. In the reported patient cohort [1], histological, clinical and laboratory findings at the time of diagnosis were unable to predict a subsequent stable or progressive disease course. Thus, we hypothesized that glomerular transcriptomics from the diagnostic kidney biopsy could help make this distinction.

METHOD

We included all progressive patients (n = 27) and patients with the stable or remitting disease (non-progressors, n = 42) from our previously reported cohort of adult patients with biopsy-proven and assumed benign IgAN (n = 192). Progression was defined as a ≥ 50% decline in eGFR from the diagnostic kidney biopsy, performed between 1988 and 1999 until follow-up examination [1]. The median follow-up time was 22 years. Glomerular cross-sections were obtained through laser-capture microdissection from archival kidney biopsy sections for RNA extraction and sequencing, using NovaSeq 6000 (Illumina, USA) at Functional Genomics Centre Zurich, Switzerland. Samples yielding insufficient sequencing quality were excluded, leaving n = 8 progressors and n = 9 non-progressors for analysis, using limma [2] and edgeR [3] in R Bioconductor.

RESULTS

In the first round of analysis, we identified 1818 differentially expressed genes (P ≤ 0.05, absolute fold change ≥ 2), of which 1562 genes were overrepresented in progressors and 256 genes were overrepresented in non-progressors. Principal component analysis and hierarchical cluster analysis revealed a separation between the two study groups, indicating that underlying transcriptomic differences are present many years prior to the overt manifestation of disease progression. Interestingly, in progressors, the nuclear factor-kappa B complex, linked to IgAN pathogenesis [4], was the most overabundant transcription factor and Fc Fragment of IgA Receptor (FCAR) was the most overrepresented differentially abundant mRNA. Ingenuity Pathway Analysis (Qiagen, USA) suggested an overrepresentation of the phagosome formation pathway (P = 3.09E-08, Z-score = 8.43), indicating phagosome activation in progressors, possibly a response to the observed FCAR overexpression. To identify potential markers for disease progression, we used an unsupervised K Nearest Neighbour analysis of 1818 differentially expressed genes, allowing combinations of ≤ 10 genes. A two-component classifier (APOL5 and ZXDC) performed best, classifying 15/17 samples correctly (sensitivity 75%, specificity 100%, accuracy 88.24%) on average 21 years prior to a manifested decrease in eGFR. Further refinements of the statistical analyses and confirmation studies are planned to substantiate our initial findings.

CONCLUSION

Glomerular mRNA sequencing performed at the time of diagnosis of assumed benign IgAN can differentiate between subsequent stable and progressive disease courses in the distant future. In our cohort, combining APOL5 and ZXDC can predict subsequent disease course with 88.24% accuracy already 21 years prior to the discovery of progression with conventional means.

Adding stress biomarkers to high-sensitivity cardiac troponin for rapid non-ST-elevation myocardial infarction rule-out protocols

AIMS

This study tested the hypothesis that combining stress-induced biomarkers (copeptin or glucose) with high-sensitivity cardiac troponin (hs-cTn) increases diagnostic accuracy for non-ST-elevation myocardial infarction (NSTEMI) in patients presenting to the emergency department.

METHODS AND RESULTS

The ability to rule-out NSTEMI for combinations of baseline hs-cTnT or hs-cTnI with copeptin or glucose was compared with the European Society of Cardiology (ESC) hs-cTnT/I-only rule-out algorithms in two independent (one Norwegian and one international multicentre) diagnostic studies. Among 959 patients (median age 64 years, 60.5% male) with suspected NSTEMI in the Norwegian cohort, 13% had NSTEMI. Adding copeptin or glucose to hs-cTnT/I as a continuous variable did not improve discrimination as quantified by the area under the curve {e.g. hs-cTnT/copeptin 0.91 [95% confidence interval (CI) 0.89-0.93] vs. hs-cTnT alone 0.91 (95% CI 0.89-0.93); hs-cTnI/copeptin 0.85 (95% CI 0.82-0.87) vs. hs-cTnI alone 0.93 (95% CI 0.91-0.95)}, nor did adding copeptin <9 mmol/L or glucose <5.6 mmol/L increase the sensitivity of the rule-out provided by hs-cTnT <5 ng/L or hs-cTnI <4 ng/L in patients presenting more than 3 h after chest pain onset (target population in the ESC-0 h-algorithm). The combination decreased rule-out efficacy significantly (both P < 0.01). These findings were confirmed among 1272 patients (median age 62 years, 69.3% male) with suspected NSTEMI in the international validation cohort, of which 20.7% had NSTEMI. A trend towards increased sensitivity for the hs-cTnT/I/copeptin combinations (97-100% vs. 91-97% for the ESC-0 h-rule-out cut-offs) was observed in the Norwegian cohort.

CONCLUSION

Adding copeptin or glucose to hs-cTnT/I did not increase diagnostic performance when compared with current ESC guideline hs-cTnT/I-only 0 h-algorithms.

Utilizing the MEST score for prognostic staging in IgA nephropathy

Background

The Oxford classification/MEST score is an established histopathologic scoring system for patients with IgA nephropathy (IgAN). The objective of this study was to derive a prognostic model for IgAN based on the MEST score and histopathologic features.

Methods

A total of 306 patients with biopsy-proven primary IgAN were included. Histopathologic samples were retrieved from the Norwegian Kidney Biopsy Registry and reclassified according to the Oxford classification. The study endpoint was end-stage renal disease (ESRD). Patients were subclassified into three risk models based on histologic features (Model A), a composite score calculated from the adjusted hazard ratio values (Model B), and on quartiles (Model C).

Results

The mean follow-up time was 16.5 years (range 0.2–28.1). In total, 61 (20%) patients reached ESRD during the study period. Univariate analysis of M, E, S, T and C lesions demonstrated that all types were associated with an increased risk of ESRD; however, a multivariate analysis revealed that only S, T and C lesions were associated with poor outcomes. Statistical analysis of 15-year data demonstrated that Models A and B were as predictive as the MEST score, with an area-under-the-curve at 0.85. The Harrel c index values were 0.81 and 0.80 for the MEST score and Models A and B, respectively. In the present cohort, adding C lesions to the MEST score did not improve the models prognostic value.

Conclusions

Patients can be divided into risk classes based on their MEST scores. Histopathologic data provide valuable prognostic information at the time of diagnosis. Model B was the most suitable for clinical practice because it was the most user-friendly.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02653-y.

Rapid syndromic PCR testing in patients with respiratory tract infections reduces time to results and improves microbial yield

Lack of rapid and comprehensive microbiological diagnosis in patients with community acquired pneumonia (CAP) hampers appropriate antimicrobial therapy. This study evaluates the real-world performance of the BioFire FilmArray Pneumonia panel plus (FAP plus) and explores the feasibility of evaluation in a randomised controlled trial. Patients presenting to hospital with suspected CAP were recruited in a prospective feasibility study. An induced sputum or an endotracheal aspirate was obtained from all participants. The FAP plus turnaround time (TAT) and microbiological yield were compared with standard diagnostic methods (SDs). 96/104 (92%) enrolled patients had a respiratory tract infection (RTI); 72 CAP and 24 other RTIs. Median TAT was shorter for the FAP plus, compared with in-house PCR (2.6 vs 24.1 h, p < 0.001) and sputum cultures (2.6 vs 57.5 h, p < 0.001). The total microbiological yield by the FAP plus was higher compared to SDs (91% (162/179) vs 55% (99/179), p < 0.0001). Haemophilus influenzae, Streptococcus pneumoniae and influenza A virus were the most frequent pathogens. In conclusion, molecular panel testing in adults with CAP was associated with a significant reduction in time to actionable results and increased microbiological yield. The impact on antibiotic use and patient outcome should be assessed in randomised controlled trials.

Comparison of rapid molecular testing methods for detecting respiratory viruses in emergency care: a prospective study

BACKGROUND

Respiratory tract infections (RTIs) caused by contagious viruses are common among patients presenting to the emergency department (ED). Early detection of these viruses can help prevent nosocomial transmission.

AIM

To investigate the efficacy of three rapid molecular methods, namely FilmArray^® Pneumonia Panel plus (FAP plus), ID NOW^™ Influenza A and B 2 (ID NOW2) point-of-care test, and an in-house real-time polymerase chain reaction (RT-PCR) test, to identify patients with viral RTIs requiring isolation in an emergency setting.

METHODS

We included a FilmArray^® Pneumonia Panel plus in the initial workup of patients with suspected RTIs during a flu season. The RT-PCR and the influenza point-of-care test were performed as part of routine diagnostics, on demand from the treating physicians. We compared viral detections and compared time to positive test results for each method.

FINDINGS

The FAP plus significantly reduced the turnaround time and was able to identify 95% patients with potential contagious viral RTI. Routine diagnostics ordered by the treating physician had a turnaround time of a median 22 h and detected 87% of patients with potential contagious viral RTI. In patients that had all three tests, the ID NOW2 detected 62% of patients with influenza.

CONCLUSIONS

The FAP plus was able to rapidly and reliably identify patients with potential contagious viral RTIs; its use was feasible in the ED setting. Failing to test patients with viral RTI and using tests with long turnaround time may lead to nosocomial transmission of viral infections and adverse patient outcomes.

Hypertensive nephrosclerosis: wider kidney biopsy indications may be needed to improve diagnostics

BACKGROUND

Hypertensive nephrosclerosis is the presumed underlying cause in many end-stage kidney disease (ESKD) patients, but the diagnosis is disputed and based on clinical criteria with low diagnostic accuracy.

OBJECTIVE

To evaluate and improve the diagnostic process for nephrosclerosis patients.

METHODS

We included adults from the population-based HUNT study (n = 50 552), Norwegian CKD patients referred for kidney biopsy 1988-2012 (n = 7261), and unselected nephrology clinic patients (n = 193) used for matching. Decision tree analysis and ROC curve-based methods of optimal cut-offs were used to improve clinical nephrosclerosis criteria.

RESULTS

Nephrosclerosis prevalence was 2.7% in the general population, and eGFR decline and risk for kidney-related hospital admissions and ESKD were comparable to patients with diabetic kidney disease. In the biopsy cohort, current clinical criteria had very low sensitivity (0.13) but high specificity (0.94) for biopsy-verified arterionephrosclerosis. A new optimized diagnostic algorithm based on proteinuria (<0.75 g d^-1 ), systolic blood pressure (>155 mm Hg) and age (>75 years) only marginally improved diagnostic accuracy (sensitivity 0.19, specificity 0.96). Likewise, there were still false-positive cases with treatable diagnoses like glomerulonephritis, interstitial nephritis and others (40% of all test positive). Decision curve analysis showed that the new criteria can lead to higher clinical utility, especially for patients considering the potential harms to be close to the potential benefits, while the more risk-tolerant ones (harm:benefit ratio < 1:4) should consider kidney biopsy.

CONCLUSION

Further improvements of the current clinical criteria seem difficult, so risks and benefits of kidney biopsy could be more actively discussed with selected patients to reduce misclassification and direct treatment.

Cardiac Troponin Assays With Improved Analytical Quality: A Trade-Off Between Enhanced Diagnostic Performance and Reduced Long-Term Prognostic Value

Background

Cardiac troponin (cTn) permits early rule‐out/rule‐in of patients admitted with possible non–ST‐segment–elevation myocardial infarction. In this study, we developed an admission and a 0/1 hour rule‐out/rule‐in algorithm for a troponin assay with measurable results in >99% of healthy individuals. We then compared its diagnostic and long‐term prognostic properties with other protocols.

Methods and Results

Blood samples were collected at 0, 1, 3, and 8 to 12 hours from patients admitted with possible non–ST‐segment–elevation myocardial infarction. cTnT (Roche Diagnostics), cTnI_(Abbott) (Abbott Diagnostics), and cTnI_(sgx) (Singulex Clarity System) were measured in 971 admission and 465 1‐hour samples. An admission and a 0/1 hour rule‐out/rule‐in algorithm were developed for the cTnI_(sgx) assay and its diagnostic properties were compared with cTnT_ESC (European Society of Cardiology), cTnI_(Abbott)ESC, and 2 earlier cTnI_(sgx) algorithms. The prognostic composite end point was all‐cause mortality and future nonfatal myocardial infarction during a median follow‐up of 723 days. non–ST‐segment–elevation myocardial infarction prevalence was 13%. The novel cTnI_(sgx) algorithms showed similar performance regardless of time from symptom onset, and area under the curve was significantly better than comparators. The cTnI_{(sgx)0/1 hour} algorithm classified 92% of patients to rule‐in or rule‐out compared with ≤78% of comparators. Patients allocated to rule‐out by the prior published 0/1 hour algorithms had significantly fewer long‐term events compared with the rule‐in and observation groups. The novel cTnI_{(sgx)0/1 hour} algorithm used a higher troponin baseline concentration for rule‐out and did not allow for prognostication.

Conclusions

Increasingly sensitive troponin assays may improve identification of non–ST‐segment–elevation myocardial infarction but could rule‐out patients with subclinical chronic myocardial injury. Separate protocols for diagnosis and risk prediction seem appropriate.

Clinical risk scores identify more patients at risk for cardiovascular events within 30 days as compared to standard ACS risk criteria: the WESTCOR study

AIMS

Troponin-based algorithms are made to identify myocardial infarctions (MIs) but adding either standard acute coronary syndrome (ACS) risk criteria or a clinical risk score may identify more patients eligible for early discharge and patients in need of urgent revascularization.

METHODS AND RESULTS

Post-hoc analysis of the WESTCOR study including 932 patients (mean 63 years, 61% male) with suspected NSTE-ACS. Serum samples were collected at 0, 3, and 8-12 h and high-sensitivity cTnT (Roche Diagnostics) and cTnI (Abbott Diagnostics) were analysed. The primary endpoint was MI, all-cause mortality, and unplanned revascularizations within 30 days. Secondary endpoint was non-ST-elevation myocardial infarction (NSTEMI) during index hospitalization. Two combinations were compared: troponin-based algorithms (ESC 0/3 h and the High-STEACS algorithm) and either ACS risk criteria recommended in the ESC guidelines, or one of eleven clinical risk scores, HEART, mHEART, CARE, GRACE, T-MACS, sT-MACS, TIMI, EDACS, sEDACS, Goldman, and Geleijnse-Sanchis. The prevalence of primary events was 21%. Patients ruled out for NSTEMI and regarded low risk of ACS according to ESC guidelines had 3.8-4.9% risk of an event, primarily unplanned revascularizations. Using HEART score instead of ACS risk criteria reduced the number of events to 2.2-2.7%, with maintained efficacy. The secondary endpoint was met by 13%. The troponin-based algorithms without evaluation of ACS risk missed three-index NSTEMIs with a negative predictive value (NPV) of 99.5% and 99.6%.

CONCLUSION

Combining ESC 0/3 h or the High-STEACS algorithm with standardized clinical risk scores instead of ACS risk criteria halved the prevalence of rule-out patients in need of revascularization, with maintained efficacy.

Proteinase-3 and myeloperoxidase serotype in relation to demographic factors and geographic distribution in anti-neutrophil cytoplasmic antibody-associated glomerulonephritis

Background

In anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis, antigen specificity varies between myeloperoxidase (MPO) and proteinase 3 (PR3). This has been reported to vary in relation to age, gender, geography and extrarenal manifestations. However, studies are difficult to compare as criteria for inclusion vary. The aim of this study was to investigate the relationship between ANCA serotype, latitude, ultraviolet (UV) radiation levels, age, gender and renal function at diagnosis in a large study with uniform inclusion criteria.

Methods

Patients with biopsy-proven ANCA-associated glomerulonephritis were identified from regional or nationwide registries in 14 centres in Norway, Sweden, the UK, the Czech Republic, Croatia, Italy and the USA during the period 2000-13. UV radiation levels for 2000-13 in Europe were obtained from the Swedish Meteorological and Hydrological Institute.

Results

A total of 1408 patients (45.2% PR3-ANCA) were included in the study. In univariable analysis, PR3-ANCA was significantly associated with male gender {odds ratio [OR] 2.12 [95% confidence interval (CI) 1.71-2.62]}, younger age [OR per year 0.97 (95% CI 0.96-0.98)] and higher glomerular filtration rate [OR per mL/min 1.01 (95% CI 1.01-1.02); P < 0.001] at diagnosis but not with latitude or UV radiation. In multivariable logistic regression analysis, latitude and UV radiation also became significant, with higher odds for PR3-ANCA positivity at northern latitudes/lower UV radiation levels. However, the latitudinal difference in MPO:PR3 ratio is smaller than differences previously reported concerning microscopic polyangiitis and granulomatosis with polyangiitis.

Conclusions

The ratio between PR3-ANCA and MPO-ANCA varies in glomerulonephritis with respect to age, gender, renal function and geographic latitude/UV radiation levels.

Exploring sex-specific differences in the presentation and outcomes of ANCA-associated vasculitis: a nationwide registry-based cohort study

PURPOSE

Sex-specific differences in the risk of end-stage renal disease (ESRD) in patients with anti-neutrophil cytoplasmic antibody-associated glomerulonephritis (ANCA-GN) stratified by histological classification have not been previously investigated.

METHODS

Patients with biopsy-verified pauci-immune necrotizing GN and positive ANCA serology in the Norwegian Kidney Biopsy Registry between 1991 and 2012 were included. Patients with ESRD during follow-up were identified from the Norwegian Renal Registry. ESRD-free survival stratified by histological classifications was investigated.

RESULTS

We analyzed 358 patients, of whom 87 progressed to ESRD during follow-up. Overall ESRD-free survival at 1 and 5 years in the entire cohort was 81 and 71% in males versus 90 and 80% in females, respectively; 94 and 84% in males versus 98 and 98% in females with focal histology, respectively; 85 and 76% in males versus 89 and 77% in females with mixed histology, respectively; 72 and 58% in males versus 90 and 78% in females with crescentic histology, respectively; and 52 and 46% in males versus 60 and 38% in females with sclerotic histology, respectively. Males had an increased risk of ESRD (adjusted hazard ratio, 2.44 [1.56-3.82]; p < 0.001).

CONCLUSION

Male sex is associated with increased risk of ESRD across all histological classes of ANCA-GN.

Cancer in ANCA-Associated Glomerulonephritis: A Registry-Based Cohort Study

BACKGROUND

Immunosuppressive therapy for antineutrophil cytoplasmic antibody-associated vasculitis has been associated with increased malignancy risk.

OBJECTIVES

To quantify the cancer risk associated with contemporary cyclophosphamide-sparing protocols.

METHODS

Patients from the Norwegian Kidney Biopsy Registry between 1988 and 2012 who had biopsy-verified pauci-immune glomerulonephritis and positive antineutrophil cytoplasmic antibody (ANCA) serology were included. Standardised incidence ratios (SIRs) were calculated to compare the study cohort with the general population.

RESULTS

The study cohort included 419 patients. During 3010 person-years, cancer developed in 41 patients (9.79%); the expected number of cancer cases was 37.5 (8.95%). The cohort had SIRs as follows: 1.09, all cancer types (95% CI, 0.81 to 1.49); 0.96, all types except nonmelanoma skin cancer (95% CI, 0.69 to 1.34); 3.40, nonmelanoma skin cancer (95% CI, 1.62 to 7.14); 3.52, hematologic cancer (95% CI, 1.32 to 9.37); 2.12, posttransplant cancer (95% CI, 1.01 to 4.44); and 1.53, during the 1-5-year follow-up after diagnosis (95% CI, 1.01 to 2.32).

CONCLUSIONS

Cancer risk did not increase significantly in this cohort with ANCA-associated glomerulonephritis. However, increased risk of nonmelanoma skin cancer, posttransplant cancer, and hematologic cancer indicates an association between immunosuppression and malignancy.

Prognostic Value of Histologic Classification of ANCA-Associated Glomerulonephritis

BACKGROUND AND OBJECTIVES

A kidney biopsy is preferred for the diagnosis of ANCA-associated vasculitis with renal involvement. The aim of our study was to evaluate the prognostic value of a histopathologic classification scheme recently proposed by an international consortium of renal pathologists in a large Norwegian cohort.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Patients diagnosed with ANCA-associated GN were included from the Norwegian Kidney Biopsy Registry 1991-2012. Renal morphology was classified as focal, mixed, crescentic, or sclerotic. Study end point was ESRD. Patients were followed from kidney biopsy to end of 2012.

RESULTS

Two hundred fifty patients with ≥10 glomeruli in the biopsy were included in our study. During a median follow-up of 3.5 years (0.7-7.6), 60 cases of ESRD occurred. Ninety-six (38%) biopsies were classified as focal, 61 (24%) biopsies were classified as mixed, 71 (28%) biopsies were classified as crescentic, and 22 (9%) biopsies were classified as sclerotic; 1- and 5-year cumulative renal survival rates were 96% and 90%, respectively, for the focal class, 86% and 75%, respectively, for the mixed class, 81% and 69%, respectively, for the crescentic class, and 56% and 51%, respectively, for the sclerotic class. By multivariate Cox regression analyses, the sclerotic class had a significantly worse renal prognosis than the focal (hazard ratio, 9.65; 95% confidence interval, 2.38 to 39.16) or combined mixed/crescentic classes (hazard ratio, 3.27; 95% confidence interval, 1.41 to 7.61), but no significant differences in outcome were observed in the crescentic class compared with the mixed class (hazard ratio, 1.13; 95% confidence interval, 0.44 to 2.87) or the combined mixed/crescentic class compared with the focal class (hazard ratio, 1.93; 95% confidence interval, 0.61 to 6.12). Accuracy by receiver operator characteristic curve analysis was estimated to be 0.72 (95% confidence interval, 0.65 to 0.80). In 108 additional patients with three to nine glomeruli in the biopsy, the prognostic value of this classification scheme was unchanged.

CONCLUSIONS

The histopathologic classification is a predictor of renal outcome of moderate quality. Merging the mixed and crescentic classes in the future could simplify the scheme.

Patient classification and outcome prediction in IgA nephropathy

OBJECTIVE

IgA Nephropathy (IgAN) is a common kidney disease which may entail renal failure, known as End Stage Kidney Disease (ESKD). One of the major difficulties dealing with this disease is to predict the time of the long-term prognosis for a patient at the time of diagnosis. In fact, the progression of IgAN to ESKD depends on an intricate interrelationship between clinical and laboratory findings. Therefore, the objective of this work has been the selection of the best data mining tool to build a model able to predict (I) if a patient with a biopsy proven IgAN will reach ESKD and (II) if a patient will reach the ESKD before or after 5 years.

MATERIAL AND METHODS

The largest available cohort study worldwide on IgAN has been used to design and compare several data-driven models. The complete dataset was composed of 1174 records collected from Italian, Norwegian, and Japanese IgAN patients, in the last 30 years. The data mining tools considered in this work were artificial neural networks (ANNs), neuro fuzzy systems (NFSs), support vector machines (SVMs), and decision trees (DTs). A 10-fold cross validation was used to evaluate unbiased performances for all the models.

RESULTS

An extensive model comparison based on accuracy, precision, recall, and f-measure was provided. Overall, the results indicate that ANNs can provide superior performance compared to the other models. The ANN for time-to-ESKD prediction is characterized by accuracy, precision, recall, and f-measure greater than 90%. The ANN for ESKD prediction has accuracy greater than 90% as well as precision, recall, and f-measure for the class of patients not reaching ESKD, while precision, recall, and f-measure for the class of patients reaching ESKD are slightly lower. The obtained model has been implemented in a Web-based decision support system (DSS).

CONCLUSIONS

The extraction of novel knowledge from clinical data and the definition of predictive models to support diagnosis, prognosis, and therapy is becoming an essential tool for researchers and clinical practitioners in medicine. The proposed comparative study of several data mining models for the outcome prediction in IgAN patients, using a large dataset of clinical records from three different countries, provides an insight into the relative prediction ability of the considered methods applied to such a disease.

Clinical decision support system for end-stage kidney disease risk estimation in IgA nephropathy patients

BACKGROUND

The progression of IgA nephropathy (IgAN) to end-stage kidney disease (ESKD) depends on several factors that are not quite clear and tangle the risk assessment. We aimed at developing a clinical decision support system (CDSS) for a quantitative risk assessment of ESKD and its timing using available clinical data at the time of renal biopsy.

METHODS

We included a total of 1040 biopsy-proven IgAN patients with long-term follow-up from Italy (N = 546), Norway (N = 441) and Japan (N = 53). Of these, 241 patients reached ESKD: 104 Italian [median time to ESKD = 5 (3-9) years], 134 Norwegian [median time to ESKD = 6 (2-11) years] and 3 Japanese [median time to ESKD = 3 (2-12) years]. We independently trained and validated two cooperating artificial neural networks (ANNs) for predicting first the ESKD status and then the time to ESKD (defined as three categories: ≤ 3 years, between > 3 and 8 years and over 8 years). As inputs we used gender, age, histological grading, serum creatinine, 24-h proteinuria and hypertension at the time of renal biopsy.

RESULTS

The ANNs demonstrated high performance for both the prediction of ESKD (with an AUC of 89.9, 93.3 and 100% in the Italian, Norwegian and Japanese IgAN population, respectively) and its timing (f-measure of 90.7% in the cohort from Italy and 70.8% in the one from Norway). We embedded the two ANNs in a CDSS available online (www.igan.net). Entering the clinical parameters at the time of renal biopsy, the CDSS returns as output the estimated risk and timing of ESKD for the patient.

CONCLUSIONS

This CDSS provides useful additional information for identifying 'high-risk' IgAN patients and may help stratify them in the context of a personalized medicine approach.

Addition of eGFR and Age Improves the Prognostic Absolute Renal Risk-Model in 1,134 Norwegian Patients with IgA Nephropathy

BACKGROUND

Predicting outcome in individual patients with IgA nephropathy (IgAN) is difficult but important. For this purpose, the absolute renal risk (ARR) model has been developed in a French cohort to calculate the risk of end-stage renal disease (ESRD) and death. ARR (0-3) is scored in individual IgAN patients based on the presence of proteinuria ≥1 g/24 h, hypertension, and severe histopathological lesions (1 point per risk factor). We have validated the ARR model in a Norwegian cohort of IgAN patients and tested whether adding data on initial estimated glomerular filtration rate (eGFR) and age improved prediction.

METHODS

IgAN patients diagnosed between 1988 and 2012 were identified in the Norwegian Kidney Biopsy Registry, and endpoints were identified by record linkage with the Norwegian Renal Registry (ESRD) and the Population Registry (deaths).

RESULTS

We identified 1,134 IgAN patients. The mean duration of follow-up was 10.2 years (range 0.0 to 25.7 years). Two hundred and fifty one patients developed ESRD and there were 69 pre-ESRD deaths. The ARR model significantly stratified the IgAN cohort according to risk of ESRD/death. The inclusion of eGFR and age significantly improved the ARR prognostic model; in the receiver operator characteristics (ROC) analysis, area under the curve (AUC) at 10-years of follow-up increased from 0.79 to 0.89, p < 0.001.

CONCLUSIONS

ARR is a suitable prognostic model for stratifying IgAN patients according to the risk of ESRD or death. Including initial eGFR and age in the model substantially improved its accuracy in our nationwide cohort.

Improved prognosis in Norwegian patients with glomerulonephritis associated with anti-neutrophil cytoplasmic antibodies

Background

Glomerulonephritis associated with anti-neutrophil cytoplasmic antibodies (ANCA) is associated with increased mortality and a high risk of end-stage renal disease (ESRD). Here, we investigated whether the prognosis has improved over the last 25 years.

Methods

Patients were identified in the Norwegian Kidney Biopsy Registry. We included all patients with pauci-immune crescentic glomerulonephritis and a positive ANCA test from 1988 to 2012. Deaths and ESRD in the cohort were identified through record linkage with the Norwegian Population Registry (deaths) and the Norwegian Renal Registry (ESRD). Outcomes of patients diagnosed in 1988–2002 were compared with outcomes of patients diagnosed in 2003–12.

Results

A cohort of 455 patients with ANCA-associated glomerulonephritis was identified. The mean follow-up was 6.0 years (range, 0.0–23.4). During the study period, 165 (36%) patients died and 124 (27%) progressed to ESRD. Compared with patients diagnosed in 1988–2002, those diagnosed in 2003–12 had higher mean initial estimated glomerular filtration rates (37 versus 27 mL/min/1.73 m²) and lower risk of ESRD (1-year risk: 13 versus 19%; 10-year risk: 26 versus 37%). The composite endpoint, ESRD or death within 0–1 year after diagnosis, was reduced from 34 to 25%. In patients over 60 years old, 1-year mortality fell from 33 to 20%.

Conclusions

In Norwegian patients with ANCA-associated glomerulonephritis, prognosis was significantly better in 2003–12 compared with 1988–2002. This improvement was probably partly due to a shorter diagnostic delay, and better therapeutic management in older patients.

Mortality in patients with IgA nephropathy

BACKGROUND

Immunoglobulin A nephropathy (IgAN) is the most common glomerulonephritis globally. Few studies have investigated mortality in patients with IgAN compared with the age- and sex-adjusted general population.

STUDY DESIGN

Cohort study with record linkage between the Norwegian Kidney Biopsy Registry, Norwegian Cause of Death Registry, and Norwegian Renal Registry.

SETTING & PARTICIPANTS

633 patients diagnosed with IgAN in 1988-2004.

PREDICTOR

Estimated glomerular filtration rate (eGFR), age, and sex.

OUTCOMES

Deaths and causes of death before and after the onset of end-stage renal disease through 2008.

RESULTS

Mean follow-up was 11.8 (range, 0-20.8) years. During the observation period, the observed number of deaths was 80 and the expected number was 42.1, resulting in a standardized mortality ratio (SMR) of 1.9 (95% CI, 1.5-2.4). Risk stratification based on initial eGFR showed that SMR was 1.0 (95% CI, 0.6-1.6) if eGFR was ≥60 mL/min/1.73 m(2), 1.9 (95% CI, 1.3-2.8) if eGFR was 30-60 mL/min/1.73 m(2), and 3.6 (95% CI, 2.6-5.0) in patients with eGFR <30 mL/min/1.73 m(2). Renal replacement therapy (RRT) was initiated in 146 patients and 35 of the 80 deaths occurred after the start of RRT. The age- and sex-adjusted SMR was not increased significantly in the pre-RRT period (1.3; 95% CI, 1.0-1.7), but was increased after initiation of RRT (4.9; 95% CI, 3.5-7.0). The most common cause of death was cardiovascular disease, accounting for 45% of all deaths.

LIMITATIONS

Treatment during follow-up is not known.

CONCLUSIONS

Mortality in patients with IgAN was twice the expected rate, but not significantly increased before RRT. The risk of end-stage renal disease was substantially higher than risk of death.

Long-term risk of ESRD in IgAN; validation of Japanese prognostic model in a Norwegian cohort

BACKGROUND

Recently, a Japanese model used to predict 10-year risk of end-stage renal disease (ESRD) in IgA nephropathy (IgAN) patients was published. We tested the applicability of the Japanese model in predicting 10- to 20-year risk of ESRD and all-cause mortality in a cohort of Norwegian IgAN patients.

METHODS

A cohort of IgAN patients (1988-2004) were identified in the Norwegian Kidney Biopsy Registry (NKBR) and ESRD or death during follow-up through 2008 was identified through record linkage with the Norwegian Renal Registry (ESRD) and the Norwegian Population Registry (deaths). Data from the NKBR were used to classify patients into nine different prognostic groups (0-1, 1-5, 5-10, 10-20, 20-30, 30-50, 50-70, 70-90 and >90% risk of ESRD) according to the Japanese prognostic model. The predicted risk was compared to the measured risk of ESRD in the different prognostic groups.

RESULTS

In eight of the nine risk groups, representing 597/633 (94%) of the patients in our cohort, the observed 10-year risk was within or close to the expected 10-year risk of ESRD. ESRD occurring after >10 years of observation was most frequent in the groups with 5-30% expected risk at 10 years of follow-up. A close association between risk of ESRD and risk of death prior to ESRD was observed.

CONCLUSIONS

The Japanese prognostic model is applicable to predict 10-year risk of ESRD in Norwegian IgAN patients. A new finding in the present study is that the model can also be used to predict which patients have the highest risk of developing ESRD after 10-20 years of follow-up as well as all-cause mortality risk.

Long-term risk of cancer in membranous nephropathy patients

BACKGROUND

There is a well-known association between membranous nephropathy (MN) and cancer, and patients with MN usually are examined for cancer at the time of diagnosis. The long-term risk of cancer after MN is not well studied.

STUDY DESIGN

Cohort study with record linkage between the Norwegian Kidney Biopsy Registry and Norwegian Cancer Registry.

SETTING & PARTICIPANTS

161 patients with MN from 1988 to 2003.

PREDICTOR

Patients with MN compared with the age- and sex-adjusted general Norwegian population.

OUTCOMES

Cancer diagnosis reported through 2003.

RESULTS

Mean duration of follow-up was 6.2 years (range, 0.1 to 15 years). 33 patients developed cancer; including 24 patients with cancer after the diagnosis of MN. Median time from diagnosis of MN to diagnosis of cancer was 60 months (range, 0 to 157 months). Mean annual incidence ratio of cancer was 2.4/100 person-years (2.1/100 person-years in the 0- to 5-year period and 2.8/100 person-years for the 5 to 15 years after kidney biopsy). During the 0 to 15 years after the diagnosis of MN, the expected number of cancers was 10.7, resulting in a standardized incidence ratio of cancer of 2.25 (95% confidence interval, 1.44 to 3.35). In the 5 to 15 years after diagnosis, standardized incidence ratio was 2.30 (95% confidence interval, 1.19 to 4.02). Patients with MN who developed cancer were older (65 versus 52 years; P < 0.001). Patients with cancer and MN had a greater mortality rate than patients without cancer (67% versus 26%; P < 0.001).

LIMITATIONS

Follow-up treatment after MN with cytotoxic and immunosuppressive medications is not known.

CONCLUSIONS

An increased risk of developing cancer is observed after the diagnosis of MN, which persists for many years.