Diagnostic accuracy of ANCA serology in ANCA-associated vasculitis with renal involvement.

BACKGROUND: Pauci-immune glomerulonephritis (GN) due to antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a common cause of crescentic GN. Despite advances in treatment, rates of mortality and progression to end-stage kidney disease remain high. Renal involvement is diagnosed by histological examination of kidney tissue. Serum ANCAs play a significant role in AAV; however, the value of serum ANCA quantification to predict renal involvement is not well-established. AIM: We aimed to evaluate the diagnostic accuracy of serum ANCA titres in diagnosing AAV with renal involvement. METHODS: We conducted a retrospective study of consecutive native kidney biopsies reported at our centre from 2016 to 2021. We included all adults who had both a kidney biopsy and ANCA serology. ANCA serology was tested using indirect immunofluorescence with reporting of titres. Antibodies to proteinase 3 and myeloperoxidase were measured using a chemiluminescent immunoassay. RESULTS: Eight hundred and forty-eight native kidney biopsies were reported during the study period. Five hundred and seven cases were included. The biopsy prevalence of pauci-immune GN in paired samples was 41/507 (8.1%). Most of the cohort had haematuria (66.6%), proteinuria (93.4%) and/or acute kidney injury (65.0%). A positive ANCA at any titre demonstrated a sensitivity of 97.6% and a specificity of 71.2% for a diagnosis of pauci-immune GN. The area under the curve for the receiver operator characteristic was 0.93 (95% confidence interval [CI]: 0.89-0.97). A cutoff ANCA titre of 1:160 provided the optimum balance between a sensitivity of 75.6% (95% CI: 59.7%-87.6%) and a specificity of 94.0% (95% CI: 91.6%-96.0%). CONCLUSIONS: ANCA titres are highly predictive of pauci-immune GN in the appropriate context. While serum ANCA quantitation may not replace renal biopsy, reporting will assist in the decision to start treatment early for patients with organ or life-threatening disease.

Complement-mediated thrombotic microangiopathy on a background of Alport syndrome: A case report.

Here we present a case of complement-mediated thrombotic microangiopathy (TMA) in a patient who has a background of Stage 5 chronic kidney disease secondary to Alport syndrome. We explain our approach to the diagnosis of TMA, especially the reliance on non-renal manifestations of TMA and the role of kidney biopsy given there was a background of advanced kidney impairment at baseline.

Does an electronic pathology ordering system change the volume and pattern of routine testing in hospital? An interrupted time series analysis.

AIMS: Identifying and reducing low-value care is a vital issue in Australia, with pathology test ordering a common focus in this field. This study builds on previous research and aimed to quantify the impact of the implementation of an electronic ordering (e-ordering) system on the volume of pathology testing, compared with manual (paper based) ordering. METHODS: An audit and analysis of pathology test data were conducted, using an interrupted time series design to investigate the impact of the e-ordering system on pathology ordering patterns. All medical and surgical adult inpatients at a tertiary referral hospital in Newcastle, Australia, were included over a 3-year period. RESULTS: Overall, there were no statistically significant differences in the volume of orders due to the implementation of the e-ordering system. There was a slight increase in the aggregated volume (tests per admission and tests per bed day) of tests ordered across the entire study period, reflecting a secular trend. CONCLUSIONS: Despite providing greater visibility and tracking of orders, we conclude that the implementation of an e-ordering system does not, in and of itself, reduce ordering volume. Efforts to identify and reduce low-value care will require intentional effort and specifically designed educational programmes or hard-wired algorithms.

Measurement of Complement Activation via Plasma-Soluble C5b-9 Comparison with Terminal Complement Complex Staining in a Series of Kidney Biopsies.

INTRODUCTION: With the emergence of therapeutic complement inhibitors, there is a need to identify patients with complement-driven inflammation. C5b-9 is the terminal product of the three complement pathways and therefore a marker of total complement activation. We present a pilot study which aims to assess whether plasma soluble C5b-9 (sC5b-9) correlates with terminal complement complex (TCC) staining in kidney tissue. The secondary aim was to assess the utility of plasma sC5b-9 as part of routine workup in kidney patients undergoing kidney biopsy. METHODS: Thirty-seven patients undergoing kidney biopsy had plasma sC5b-9 and TCC staining on kidney tissue performed. Additional blood markers including creatinine, haemoglobin, CRP, factor H, factor I, and midkine levels were also taken. These parameters were correlated with the histological diagnoses. Patients were divided into a diseased group (n = 31) and a control group (n = 6) consisting of transplanted kidneys with minor or no changes. Of the biopsies in the control group, 50% were performed as per protocol, and the other 50% were performed due to clinical need. RESULTS: There was no correlation found between plasma sC5b-9 and TCC kidney staining. Elevated sC5b-9 levels were found in a heterogeneous group of patients but were associated with higher CRP and lower haemoglobin levels. Overall, there was more TCC kidney staining in the diseased group compared with the control group, and a trend was observed of diabetic, primary membranous nephropathy, and amyloidosis patients having more intense glomerular and peritubular/interstitial staining. CONCLUSION: Plasma sC5b-9 as a marker of total complement activation does not correlate with TCC kidney staining. This discordance suggests that plasma sC5b-9 and TCC staining are distinct markers of disease. TCC staining reflects chronicity and tissue deposition of complement over time. Conversely, plasma sC5b-9 concentrations change rapidly and reflect systemic complement activation. Complement activation was present in a heterogeneous group of kidney disease, indicating the underlying role of complement in many disorders.

Anti-tissue transglutaminase (tTG) screening using relative light units to identify IgA deficiency.

IgA deficiency is more common in patients with coeliac disease (CD). Total IgA levels are often recommended as part of first line coeliac testing along with anti-tissue transglutaminase (tTG) IgA, to identify these patients and reduce falsely negative results. This study aimed to identify patients with complete IgA deficiency by determining a cut-off threshold on chemiluminescent tTG IgA testing. A chemiluminescent assay QUANTA Flash h-tTG was reviewed using the BIO-FLASH automated platform. tTG relative light units (RLU) were analysed in relation to total IgA levels. Correlation analysis was performed and distributions of tTG RLU were compared between the IgA deficient and IgA detectable groups, and ROC analysis was performed to identify a suitable threshold. A total of 203 samples were reviewed in our initial cohort. There was a strong correlation between IgA and tTG RLU levels (Pearson correlation coefficient 0.495, p<0.001). There was a statistically significant difference of 170.57 RLU between the means of the IgA deficient and IgA detectable group (p<0.001, 156.50-184.64). A receiver operating characteristic (ROC) curve was generated with area under the curve of 0.997. A cut-off of less than 300 tTG RLU for identification of IgA deficiency was chosen, which had a sensitivity and specificity of 100% and 98.9%, respectively. A prospective validation cohort was conducted which confirmed the initial results. Our study has validated an algorithm to identify complete IgA deficiency by implementing a threshold of 300 RLU during tTG IgA testing by chemiluminescent immunoassay. This approach resulted in a sensitivity of 100% to detect patients with complete IgA deficiency. Widespread uptake would result in improved workflow, workload and turnaround time, and reduce the need for unnecessary blanket testing of total IgA in the screening for coeliac disease.

Biomarkers to Guide the Timing of Surgery: Neutrophil and Monocyte L-Selectin Predict Postoperative Sepsis in Orthopaedic Trauma Patients.

Deciding whether to delay non-lifesaving orthopaedic trauma surgery to prevent multiple organ failure (MOF) or sepsis is frequently disputed and largely based on expert opinion. We hypothesise that neutrophils and monocytes differentially express activation markers prior to patients developing these complications. Peripheral blood from 20 healthy controls and 162 patients requiring major orthopaedic intervention was collected perioperatively. Neutrophil and monocyte L-selectin, CD64, CD11, CD18, and CXCR1 expression were measured using flow cytometry. The predictive ability for MOF and sepsis was assessed using the Receiver Operating Characteristic (ROC) comparing to C-reactive protein (CRP). Neutrophil and monocyte L-selectin were significantly higher in patients who developed sepsis. Neutrophil L-selectin (AUC 0.692 [95%CI 0.574-0.810]) and monocyte L-selectin (AUC 0.761 [95%CI 0.632-0.891]) were significant predictors of sepsis and were not significantly different to CRP (AUC 0.772 [95%CI 0.650-0.853]). Monocyte L-selectin was predictive of MOF preoperatively and postoperatively (preop AUC 0.790 [95%CI 0.622-0.958]). CD64 and CRP were predictive of MOF at one-day postop (AUC 0.808 [95%CI 0.643-0.974] and AUC 0.809 [95%CI 0.662-0.956], respectively). In the perioperative period, elevated neutrophil and monocyte L-selectin are predictors of postoperative sepsis. Larger validation studies should focus on these biomarkers for deciding the timing of long bone/pelvic fracture fixation.

Genomic investigation of inherited thrombotic microangiopathy-aHUS and TTP.

Thrombotic microangiopathies (TMA) are a heterogeneous group of red cell fragmentation syndromes characterized by a tendency for thrombosis and pathognomonic red cell fragments in peripheral blood, which results in thrombosis in the microvasculature due to endothelial damage. Genomic investigations into inherited TMAs are of diagnostic, prognostic and therapeutic value. Here, we present two cases that capture the importance of performing genomic testing in rare disorders. Treatment options for these conditions, such as plasma exchange and monoclonal antibodies against complement factors, are intensive and expensive health care interventions. The results of genomic investigation into rare TMAs can better inform the clinicians and their patients of prognosis and suitable personalized treatment options.

Heparin Administration, but Not Myocardial Ischemia or Necrosis, Leads to Midkine Elevation.

Midkine (MK) is a heparin-binding growth factor, whose role as a biomarker of coronary artery disease, myocardial ischaemia and necrosis has not been well measured. This study quantified serial MK levels in patients undergoing coronary angiography (CA) and identified factors associated with MK. In this single-centre, parallel cohort study, forty patients undergoing CA had arterial samples collected prior, 10 and 20 min after heparin administration. Four groups were examined: 1-stable coronary artery disease (CAD) without percutaneous coronary intervention (PCI); 2-stable CAD for elective PCI; 3-non-ST elevation myocardial infarction (NSTEMI) with or without PCI; 4-ST elevation myocardial infarction (STEMI) with primary PCI. Groups 1, 2 and 4 were heparin naïve, allowing assessment of the effects of myocardial necrosis between baseline levels; group 3 had received low-molecular-weight heparin. MK levels were analysed by ELISA. Median MK at baseline did not differ between groups, demonstrating that myocardial ischaemia or necrosis does not affect MK levels. Heparin administration had an immediate effect on median MK at 10 min, showing an average 500-fold increase that is dose-dependent (R2 = 0.35, p = 0.001). Median MK levels remained elevated at 20 min following heparin administration. Multivariate analysis showed that the estimated glomerular filtration rate (eGFR) was the only predictor of elevated baseline MK (p = 0.02). Baseline MK did not correlate with high-sensitivity troponin-I (HsTnI) taken just before CA (p = 0.97), or peak HsTnI during admission (p = 0.74). MK is not a reliable marker of myocardial ischaemia or necrosis. MK increased significantly in all patients following heparin administration in a dose-dependent manner.

An international multi-center serum protein electrophoresis accuracy and M-protein isotyping study. Part II: limit of detection and follow-up of patients with small M-proteins.

Background Electrophoretic methods to detect, characterize and quantify M-proteins play an important role in the management of patients with monoclonal gammopathies (MGs). Significant uncertainty in the quantification and limit of detection (LOD) is documented when M-proteins are <10 g/L. Using spiked sera, we aimed to assess the variability in intact M-protein quantification and LOD across 16 laboratories. Methods Sera with normal, hypo- or hyper-gammaglobulinemia were spiked with daratumumab or elotuzumab, with concentrations from 0.125 to 10 g/L (n = 62) along with a beta-migrating sample (n = 9). Laboratories blindly analyzed samples according to their serum protein electrophoresis (SPEP)/isotyping standard operating procedures. LOD and intra-laboratory percent coefficient of variation (%CV) were calculated and further specified with regard to the method (gel/capillary electrophoresis [CZE]), gating strategy (perpendicular drop [PD]/tangent skimming [TS]), isotyping (immunofixation/immunosubtraction [ISUB]) and manufacturer (Helena/Sebia). Results All M-proteins ≥1 g/L were detected by SPEP. With isotyping the LOD was moderately more sensitive than with SPEP. The intensity of polyclonal background had the biggest negative impact on LOD. Independent of the method used, the intra-laboratory imprecision of M-protein quantification was small (mean CV = 5.0%). Low M-protein concentration and high polyclonal background had the strongest negative impact on intra-laboratory precision. All laboratories were able to follow trend of M-protein concentrations down to 1 g/L. Conclusions In this study, we describe a large variation in the reported LOD for both SPEP and isotyping; overall LOD is most affected by the polyclonal immunoglobulin background. Satisfactory intra-laboratory precision was demonstrated. This indicates that the quantification of small M-proteins to monitor patients over time is appropriate, when subsequent testing is performed within the same laboratory.

An international multi-center serum protein electrophoresis accuracy and M-protein isotyping study. Part I: factors impacting limit of quantitation of serum protein electrophoresis.

Background Serum protein electrophoresis (SPEP) is used to quantify the serum monoclonal component or M-protein, for diagnosis and monitoring of monoclonal gammopathies. Significant imprecision and inaccuracy pose challenges in reporting small M-proteins. Using therapeutic monoclonal antibody-spiked sera and a pooled beta-migrating M-protein, we aimed to assess SPEP limitations and variability across 16 laboratories in three continents. Methods Sera with normal, hypo- or hypergammaglobulinemia were spiked with daratumumab, Dara (cathodal migrating), or elotuzumab, Elo (central-gamma migrating), with concentrations from 0.125 to 10 g/L (n = 62) along with a beta-migrating sample (n = 9). Provided with total protein (reverse biuret, Siemens), laboratories blindly analyzed samples according to their SPEP and immunofixation (IFE) or immunosubtraction (ISUB) standard operating procedures. Sixteen laboratories reported the perpendicular drop (PD) method of gating the M-protein, while 10 used tangent skimming (TS). A mean percent recovery range of 80%-120% was set as acceptable. The inter-laboratory %CV was calculated. Results Gamma globulin background, migration pattern and concentration all affect the precision and accuracy of quantifying M-proteins by SPEP. As the background increases, imprecision increases and accuracy decreases leading to overestimation of M-protein quantitation especially evident in hypergamma samples, and more prominent with PD. Cathodal migrating M-proteins were associated with less imprecision and higher accuracy compared to central-gamma migrating M-proteins, which is attributed to the increased gamma background contribution in M-proteins migrating in the middle of the gamma fraction. There is greater imprecision and loss of accuracy at lower M-protein concentrations. Conclusions This study suggests that quantifying exceedingly low concentrations of M-proteins, although possible, may not yield adequate accuracy and precision between laboratories.

Identifying low value pathology test ordering in hospitalised patients: a retrospective cohort study across two hospitals.

The push to identify low value care has led to scrutiny of pathology test re-ordering. The objective of this study was to identify the patterns of ordering pathology tests among inpatients in teaching hospitals and model strategies to reduce unnecessary testing. This was a retrospective cohort study of all adult medical and surgical inpatients admitted to one major teaching hospital and one rural hospital in the same health district over 2 years. Obstetric, gynaecological, intensive care, elective/day procedures and dialysis admissions were excluded. Orders for electrolytes, urea and creatinine (EUC), full blood count (FBC), thyroid stimulating hormone (TSH), glycated haemoglobin (HbA1c), vitamin D, and troponin, date of order, and value of the resulting test, were obtained from a health district data warehouse. Pathology results were mapped to each inpatient day. EUC and FBC constituted over 90% of all inpatient pathology requests for these six tests. Between 40-45% of inpatients had EUC and/or FBC performed daily. After the first couple of tests, the retest interval was consistently around 24 hours, regardless of the previous value of the test, consistent with a culture of routine ordering. This was less pronounced in the rural hospital compared to the urban teaching hospital. Lockouts (applied when previous tests normal) or minimum retest intervals (applied to previously normal and abnormal tests) of various lengths were tested on the data to find optimal combinations that reduced unnecessary tests without missing too many very abnormal tests. A lockout of 48 hours for EUC and 48 hour lockout combined with a 12 hour minimum retest interval for FBC appear optimal to reduce over ordering and could save approximately AU$400/inpatient bed per year at a single teaching hospital. There is evidence of low value re-ordering of EUC and FBC pathology tests. Implementation of a computerised physician order entry system with inbuilt prompts to restrict unnecessary re-ordering of pathology tests may be a practical solution.

Consensus opinion on diagnosis and management of thrombotic microangiopathy in Australia and New Zealand.

Thrombotic microangiopathy (TMA) arises in a variety of clinical circumstances with the potential to cause significant dysfunction of the kidneys, brain, gastrointestinal tract and heart. TMA should be considered in all patients with thrombocytopenia and anaemia, with an immediate request to the haematology laboratory to look for red cell fragments on a blood film. Although TMA of any aetiology generally demands prompt treatment, this is especially so in thrombotic thrombocytopenic purpura (TTP) and atypical haemolytic uraemic syndrome (aHUS), where organ failure may be precipitous, irreversible and fatal. In all adults, urgent, empirical plasma exchange (PE) should be started within 4-8 h of presentation for a possible diagnosis of TTP, pending a result for ADAMTS13 (a disintegrin and metalloprotease thrombospondin, number 13) activity. A sodium citrate plasma sample should be collected for ADAMTS13 testing prior to any plasma therapy. In children, Shiga toxin-associated haemolytic uraemic syndrome due to infection with Escherichia coli (STEC-HUS) is the commonest cause of TMA, and is managed supportively. If TTP and STEC-HUS have been excluded, a diagnosis of aHUS should be considered, for which treatment is with the monoclonal complement C5 inhibitor, eculizumab. Although early confirmation of aHUS is often not possible, except in the minority of patients in whom auto-antibodies against factor H are identified, genetic testing ultimately reveals a complement-related mutation in a significant proportion of aHUS cases. The presence of other TMA-associated conditions (e.g. infection, pregnancy/postpartum and malignant hypertension) does not exclude TTP or aHUS as the underlying cause of TMA.

Consensus opinion on diagnosis and management of thrombotic microangiopathy in Australia and New Zealand.

Thrombotic microangiopathy (TMA) arises in a variety of clinical circumstances with the potential to cause significant dysfunction of the kidneys, brain, gastrointestinal tract and heart. TMA should be considered in all patients with thrombocytopenia and anaemia, with an immediate request to the haematology laboratory to look for red cell fragments on a blood film. While TMA of any aetiology generally demands prompt treatment, this is especially so in thrombotic thrombocytopenic purpura (TTP) and atypical haemolytic uraemic syndrome (aHUS), where organ failure may be precipitous, irreversible and fatal. In all adults, urgent, empirical plasma exchange (PE) should be started within 4-8 h of presentation for a possible diagnosis of TTP, pending a result for ADAMTS13 activity (a disintegrin and metalloprotease thrombospondin, number 13). A sodium citrate plasma sample should be collected for ADAMTS13 testing prior to any plasma therapy. In children, Shiga toxin-associated haemolytic uraemic syndrome due to infection with Escherichia coli (STEC-HUS) is the commonest cause of TMA, and is managed supportively. If TTP and STEC-HUS have been excluded, a diagnosis of aHUS should be considered, for which treatment is with the monoclonal complement C5 inhibitor, eculizumab. While early confirmation of aHUS is often not possible, except in the minority of patients in whom autoantibodies against factor H are identified, genetic testing ultimately reveals a complement-related mutation in a significant proportion of aHUS cases. The presence of other TMA-associated conditions (e.g. infection, pregnancy/postpartum and malignant hypertension) does not exclude TTP or aHUS as the underlying cause of TMA.

Chronic granulomatous disease presenting as refractory pneumonia in late adulthood.

We present a case of refractory pneumonia in an adult patient with underlying chronic granulomatous disease (CGD). Her lobectomy tissue grew B urkholderia cepacia and histopathology revealed diffuse severe pneumonic consolidation with suppurative/necrotizing granulomata. An initial attempt to find an underlying immune deficiency was unsuccessful. Following recurrent invasive infections, repeat immunological assessment revealed reduced neutrophil function, demonstrating skewed carrier status (lyonization) for X-linked CGD (only 3% normal cells). A pathogenic mutation in the CYBB gene was found on sequencing. CYBB gene encodes the gp91phox, a catalytic subunit of nicotinamide adenine dinucleotide phosphate-oxidase that produces reactive oxygen species in phagocytes. Lyonization increases with age, explaining the delayed clinical CGD. CGD is a rare neutrophil disorder that usually presents in early life with recurrent infections due to bacteria and fungi primarily involving lungs and skin. It is secondary to a defective NADPH oxidase system needed to kill intracellular organisms and activate the formation of neutrophil extracellular traps.

The role of inflammatory markers in explaining the association between depression and cardiovascular hospitalisations.

This study investigated whether inflammation may explain the relationship between depression and incident cardiovascular hospitalisations. Participants (55-85 years) completed baseline depression and physical assessment. Those without self-reported cardiovascular events were followed prospectively for hospital admissions for angina, myocardial infarction and cerebral infarction (median 937 days). Across 5140 person-years of risk (N = 1692), there were 47 incident cardiovascular hospitalisations (2.8 %). Controlling for age and gender, interleukin (IL)-6, C-reactive protein (CRP), body mass index (BMI) and waist-to-hip ratio were associated with future cardiovascular events. Mediation analysis showed that CRP accounted for 8.1 % and IL-6 10.9 % of the effect of depression on cardiovascular events, and including the indirect effect in the model substantially reduced the direct relationship between depression and cardiovascular hospitalisations. BMI and waist-to-hip ratio accounted for indirect effects of 7.7 and 10.4 %, respectively. Inflammatory markers partly explain the association between depression and cardiovascular events, although other shared factors also likely contribute.

Unhealthy lifestyle may increase later depression via inflammation in older women but not men.

Depression and inflammatory markers have a reliable cross-sectional association although less is known about the prospective relationship. The current study investigated whether pro-inflammatory markers are prospectively associated with depression, and whether indicators of unhealthy lifestyle, physical health and psychosocial functioning may drive this association. Participants were drawn from the Hunter Community Study, a community-dwelling cohort of individuals aged 55-85 years (N = 1410). Participants completed baseline physiological assessment, health-related questionnaires, and blood sampling for the analysis of inflammatory markers, C-reactive protein (CRP) and interleukin (IL)-6. Participants completed the same depressive symptom questionnaire again after 3.5-5.5 years. Depression outcomes at follow-up were analysed dichotomously using established scale cut-off scores and continuously as a "residual score", representing the variation in follow-up depressive symptoms not explained by baseline symptoms and age. Analyses were conducted on males and females separately. At baseline, indicators of unhealthy lifestyle, physical health and psychosocial functioning were associated with depressive symptoms and inflammatory markers. For males, there were no relationships between inflammatory markers and follow-up depression outcomes. In females, IL-6 was significantly associated with depression outcomes in univariate, but not multivariate analyses. However, IL-6 significantly mediated the association between the predictors of waist-to-hip ratio, smoking and psychological coping at baseline, and follow-up depression outcomes. The results support the inflammatory hypothesis of depression, although females may be more vulnerable to effects. The findings raise the possibility that unhealthy lifestyle and psychosocial stress may drive inflammation and subsequent depressive symptoms.