Does a gating policy for ANCA overlook patients with ANCA associated vasculitis? An audit of 263 patients

Indications and diagnostic outcome of antineutrophil cytoplasmic antibody testing in hospital medicine: a pattern of over-screening

INTRODUCTION/OBJECTIVE

Antineutrophil cytoplasmic antibodies (ANCA) serology can aid in the diagnosis and classification of ANCA-associated vasculitides (AAV). However, it is often ordered in patients without clinical manifestations of vasculitis. In this retrospective chart review, we aim to better understand the clinical practices on ANCA testing.

METHODS

We retrospectively reviewed patients' charts for the indications and diagnostic outcomes of ANCA tests. All ANCA tests ordered at two Canadian hospitals (a community hospital and an academic tertiary hospital) between January and December 2016 were included in the study. Descriptive statistics are used.

RESULTS

A total of 302 ANCA tests were included. The majority (n = 198, 65.6%) were ordered without an indication for testing. For those patients with at least 1 clinical manifestation of AAV (n = 104), 25% were ANCA positive and 18.3% resulted in a diagnosis of AAV. In comparison, among those without a clinical manifestation of AAV (n = 198), only 1.5% were ANCA positive and none was diagnosed with AAV. All patients diagnosed with AAV had at least 1 indication for ANCA testing. The three most common clinical presentations in patients with a final diagnosis of AAV were glomerulonephritis (81.8%), pulmonary hemorrhage (45.5%), and multiple lung nodules (31.8%).

CONCLUSION

To our knowledge, this is the first study that evaluates patients with both positive and negative ANCA test results in an inpatient setting. We demonstrated a low rate of ANCA positivity and AAV diagnosis in patients without clinical manifestations of AAV. Overall, there is a high rate of ANCA testing without an indication at our academic institution. This over-testing may be curbed by strategies such as a gating policy, culture changes, and clinician education. Key Points • AAV is a clinical-pathological diagnosis, and despite the usefulness of ANCA testing, it does not confirm nor rule out AAV. • ANCA testing for the diagnosis of AAV is generally only indicated when there is a clear manifestation of AAV. • Although patients with AAV may occasionally present without classic signs and symptoms, the diagnostic utility of ANCA serology in this setting is low, and testing is more likely to result in a false-positive or false-negative test. • If clinical suspicion remains high despite negative ANCA testing, clinicians should seek consultation with a rheumatologist.

ANCA Testing in Clinical Practice: From Implementation to Quality Control and Harmonization

Analyses for the presence of anti-neutrophil cytoplasmic antibodies (ANCA) are important in the diagnostic work-up of patients with small vessel vasculitis. Since current immuno-assays are predominantly designed for diagnosis of patients with ANCA-associated vasculitis (AAV), implementation in routine clinical practice, internal and external quality control, and harmonization are focused on this particular use. However, ANCA testing may also be relevant for monitoring therapy efficacy and for predicting a clinical relapse in AAV patients, and even for diagnostic purposes in other clinical situations. In the current review, the topics of implementation, quality control, and standardization vs. harmonization are discussed while taking into account the different applications of the ANCA assays in the context of AAV.

Clinical implications of ANCA positivity in a hospital setting: a tertiary center experience

ANCA testing plays an established critical role in the diagnosis of ANCA Associated vasculitis (AAV). The spectrum of diseases associated with positive ANCA has recently broadened, thus calling into question the diagnostic implications of ANCA positivity in a hospital setting. We retrospectively studied all adult patients who had a positive ANCA test (by Indirect Immunofluorescence (IIF), ELISA or both) performed over the span of 19 years. Subjects were then divided into discordant (positive on one assay) and concordant ANCA (positive on both assays) groups based on their ANCA positivity status. The two groups were then compared with regards to their demographic, clinical and laboratory characteristics, the indication for ANCA testing in both groups and their final diagnoses. Of the 9189 ANCA tests ordered during the 19-year span of the study, 389 (4.2%) were positive. Two hundred and forty subjects met the exclusion criteria (patients aged less than 18 years or the lack of clinical and laboratory data in the medical file) thus resulting in a final cohort of 149 subjects. Of them, 122 subjects had discrepant ANCA results and 27 had matching ANCA results. Most cases in the discrepancy group were IIF positive and ELISA negative (86.8%). The diagnosis of AAV was highly unlikely in cases with discrepant IIF and ELISA serologies compared to cases with matching IIF and ELISA serologies (4.1% versus 44.4%, p value < 0.001). The diagnosis of AAV in unlikely in subjects with discrepancies between IIF and ELISA, particularly with only positive IIF.

The perspective on standardisation and harmonisation: the viewpoint of the EASI president

Standardisation of immuno-assays for autoantibodies is a major challenge. Although multiple organisations participate in the generation of internationally accepted standards, adequate standardisation of assays has not yet been achieved. Harmonisation may offer an alternative approach to better align requesting, testing, reporting and interpretation of autoimmune diagnostics. The European Autoimmunity Standardisation Initiative (EASI) was founded to facilitate both standardisation as well as harmonisation of autoantibody tests, but over the years the focus has drifted away from standardisation in favour of harmonisation. In the current paper the options for harmonisation are highlighted.

The Diagnostic and Clinical Utility of Autoantibodies in Systemic Vasculitis

Considerable progress has been made in understanding the role of autoantibodies in systemic vasculitides (SV), and consequently testing for anti-neutrophil cytoplasmic antibodies (ANCA), anti-glomerular basement membrane antibodies (anti-GBM), and anti-C1q antibodies is helpful and necessary in the diagnosis, prognosis, and monitoring of small-vessel vasculitis. ANCA-directed proteinase 3 (PR3-) or myeloperoxidase (MPO-) are sensitive and specific serologic markers for ANCA-associated vasculitides (AAV), anti-GBM antibodies are highly specific for the patients with anti-GBM antibody disease (formerly Goodpasture’s syndrome), and autoantibodies to C1q are characteristic of hypocomlementemic urticarial vasculitis syndrome (HUVS; anti-C1q vasculitis). The results of a current EUVAS study have led to changes in the established strategy for the ANCA testing in small-vessel vasculitis. The revised 2017 international consensus recommendations for ANCA detection support the primary use PR3- and MPO-ANCA immunoassays without the categorical need for additional indirect immunofluorescence (IIF). Interestingly, the presence of PR3- and MPO-ANCA have led to the differentiation of distinct disease phenotype of AAV: PR3-ANCA-associated vasculitis (PR3-AAV), MPO-ANCA-associated vasculitis (MPO-AAV), and ANCA-negative vasculitis. Further studies on the role of these autoantibodies are required to better categorize and manage appropriately the patients with small-vessel vasculitis and to develop more targeted therapy.

EVOLVE: The Australian Rheumatology Association's 'top five' list of investigations and interventions doctors and patients should question

BACKGROUND

The EVOLVE (evaluating evidence, enhancing efficiencies) initiative aims to drive safer, higher-quality patient care through identifying and reducing low-value practices.

AIMS

To determine the Australian Rheumatology Association's (ARA) 'top five' list of low-value practices.

METHODS

A working group comprising 19 rheumatologists and three trainees compiled a preliminary list. Items were retained if there was strong evidence of low value and there was high or increasing clinical use and/or increasing cost. All ARA members (356 rheumatologists and 72 trainees) were invited to indicate their 'top five' list from a list of 12-items through SurveyMonkey in December 2015 (reminder February 2016).

RESULTS

A total of 179 rheumatologists (50.3%) and 19 trainees (26.4%) responded. The top five list (percentage of rheumatologists, including item in their top five list) was: Do not perform arthroscopy with lavage and/or debridement for symptomatic osteoarthritis of the knee nor partial meniscectomy for a degenerate meniscal tear (73.2%); Do not order anti-nuclear antibody (ANA) testing without symptoms and/or signs suggestive of a systemic rheumatic disease (56.4%); Do not undertake imaging for low back pain for patients without indications of an underlying serious condition (50.8%); Do not use ultrasound guidance to perform injections into the subacromial space as it provides no additional benefit in comparison to landmark-guided injection (50.3%) and Do not order anti-double-stranded DNA antibodies in ANA negative patients unless the clinical suspicion of systemic lupus erythematosus remains high (45.3%).

CONCLUSIONS

This list is intended to increase awareness among rheumatologists, other clinicians and patients about commonly used low-value practices that should be questioned.

What does it mean if a patient is positive for anti-Jo-1 in routine hospital practice? A retrospective nested case-control study

Background:  It is widely believed that patients bearing auto-antibodies to histidyl tRNA synthetase (anti-Jo-1) very likely have a connective tissue disease including myositis and interstitial lung disease.  The value of positive tests in low disease prevalence settings such as those tested in routine care is unknown.  We sought to determine the value of anti-Jo-1 auto-antibodies in routine practice. Methods: Our study was a nested case control study within a retrospective cohort of all patients tested for anti-ENA our hospital, from any hospital department, between January 2013 and December 2014.  Data was extracted from electronic records of anti-Jo-1 positive patients and randomly selected ENA negative patients (ratio of 1:2), allowing for a minimum follow up of at least 12 months after first testing. Results: 4009 samples (3581 patients) were tested.  Anti-ENA was positive in 616 (17.2%) patients, 40 (1.1%) were anti-Jo-1 positive. Repeat ENA testing was done for 350/3581 (9.8%) patients (428 of 4009 (10.7%) samples) and in 7/40 (17.5%) of anti-Jo-1 positive patients. The median interval between the first and second request was 124 days (inter-quartile range 233 days).  The frequencies of interstitial lung disease (ILD), myositis and Raynaud's were comparable for anti-Jo-1 positive patients (n=40) and 80 randomly selected ENA negative controls.  Positive tests led to additional diagnostic testing in the absence of clinical disease.  Sensitivity of Jo-1 for ILD was 50% (CI 19-81%), specificity 68% (CI 59-77%), positive predictive value 12.5% (CI 4 to 27%) and negative predictive value 93.8% (CI 86-98%). Of 10 (25%) patients with high anti-Jo1 levels, 3 had ILD, one myositis and two a malignancy (disseminated melanoma and CML).  Conclusion: Anti-Jo-1 is uncommon in a heterogenous hospital population and is only weakly predictive for ILD.  Repeated test requests were common and potentially unnecessary indicating that controls over repeat requests could yield significant cost savings.

New concepts in ANCA detection and disease classification in small vessel vasculitis: the role of ANCA antigen specificity

Anti-neutrophil cytoplasmic antibodies (ANCA) play a central role in the diagnosis and pathogenesis of patients with ANCA-associated vasculitis. ANCA-associated vasculitis is a rare disease characterized by necrotizing inflammation of small/medium-sized blood vessels with and without granuloma in different organs. The main syndromes are granulomatosis with polyangiitis, microscopic polyangiitis, and eosinophilic GPA. ANCA in these diseases are almost always directed against proteinase 3 and myeloperoxidase. Most laboratories worldwide use as standard the indirect immunofluorescence technique to screen for ANCA and then confirm positive IFT results with antigen specific immunoassyas for PR3- and MPO-ANCA. New guidelines for ANCA testing have been developed based on a recent European multicentre study, and according to the revised 2017 international consensus recommendations, testing for ANCA in small vessel vasculitis can be done by PR3- and MPO-ANCA immunoassays, without the categorical need for IIF. The new testing strategy for ANCA in vasculitis directly identifies the ANCA target antigen and has a particular value for the AAV sub-classification. Recent studies have shown that AAV can be classified based on ANCA serotype. ANCA presence and the antigen specificity also may have important value as a prognostic factor and may serve as a guide for immunosuppressive therapy. The clinical utility of ANCA depends on the type of assay performed and the appropiate ordering of testing the right clinical setting. Accurate identification of all patients with AAV and the avoidance of misdiagnosis can be achieved using a "gating policy" based on clinical information given to the laboratory at the time of request.

Anti-neutrophil cytoplasm antibodies (ANCA): Recent methodological advances-Lead to new consensus recommendations for ANCA detection

The current practice for detection of anti-neutrophil cytoplasm antibodies (ANCA) directed against proteinase 3 (PR3) and myeloperoxidase (MPO) has been screening by indirect immunofluorescence (IIF) followed by an antigen specific tests for PR3- and MPO-ANCA. However, ANCA diagnostics have undergone many technical developments that have affected the 1999 international consensus recommendations, and lead to a revision of the existing ANCA detection strategy. Recent European multicentre studies have compared the diagnostic performance of various ANCA detection methods and demonstrated that PR3- and MPO-ANCA immunoassays yielded the highest diagnostic accuracy. New guidelines for ANCA testing have been developed based on these data. According to the revised 2017 international consensus recommendations, testing for ANCA in small vessel vasculitis can be done by PR3- and MPO-ANCA immunoassays, without the categorical need for IIF. Thus, IIF can be discarded completely, or can be used as confirmation assays instead a screening test. Clearly, though, the new testing strategy for ANCA in vasculitis must identify the ANCA target antigen, as PR3- and MPO-ANCA serotype correlate well with disease expression. Furthermore, recent studies have shown that AAV can be classified based on ANCA serotype, since PR3- and MPO-ANCA- diseases are strongly associated with distinguishable genetic alleles, different clinical and histological features. ANCA presence and the antigen specificity also may have important value as a prognostic factor and may serve as a guide for immunosuppressive therapy. In the current review, we summarize the novelties in ANCA testing, present the 2017 revised international consensus on ANCA testing in vasculitis, evaluate the diagnostic significance of ANCA, and discuss the role of ANCA serotypes in the diagnostic work-up of patients with AAV.

Position paper: Revised 2017 international consensus on testing of ANCAs in granulomatosis with polyangiitis and microscopic polyangiitis

Anti-neutrophil cytoplasmic antibodies (ANCAs) are valuable laboratory markers used for the diagnosis of well-defined types of small-vessel vasculitis, including granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA). According to the 1999 international consensus on ANCA testing, indirect immunofluorescence (IIF) should be used to screen for ANCAs, and samples containing ANCAs should then be tested by immunoassays for proteinase 3 (PR3)-ANCAs and myeloperoxidase (MPO)-ANCAs. The distinction between PR3-ANCAs and MPO-ANCAs has important clinical and pathogenic implications. As dependable immunoassays for PR3-ANCAs and MPO-ANCAs have become broadly available, there is increasing international agreement that high-quality immunoassays are the preferred screening method for the diagnosis of ANCA-associated vasculitis. The present Consensus Statement proposes that high-quality immunoassays can be used as the primary screening method for patients suspected of having the ANCA-associated vaculitides GPA and MPA without the categorical need for IIF, and presents and discusses evidence to support this recommendation.

Antineutrophil cytoplasmic antibody (ANCA) testing: Audit from a clinical immunology laboratory

AIM

Anti-neutrophil cytoplasmic antibodies (ANCA) are associated with small vessel vasculitis now termed 'ANCA associated vasculitis' (AAV). ANCAs are reported in diverse diseases where they have no clinical utility. We carried out an audit in a clinical immunology laboratory and assessed if use of ordering practices could have improved utility of ANCA.

METHODS

All samples received for ANCA testing during 2014 were tested by indirect immunofluorescence (IIF) and automated enzyme-linked immunosorbent assay (ELISA). Clinical records of all samples positive by one or more assays were retrieved. We assessed the effect of applying proposed test ordering guidelines on performance of the tests.

RESULTS

Of 1590 samples, 108 (6.8%) had a positive result by at least one method. IIF showed perinuclear pattern in 72 (21 were antinuclear antibody positive), cytoplasmic in 22, six had atypical pattern and eight were negative. By ELISA anti-myeloperoxidase antibodies were present in 33 samples, anti-proteinase 3 in 24, while five sera had both antibodies. ELISA and IIF were concordant in 45 samples. Twenty-seven patients had AAV of which 23 were both ELISA and IIF positive. Among these 27 with AAV all had at least one ordering criteria, while in 81 patients without AAV but with positive test, 38 had no ordering criteria.

CONCLUSION

Reduction in false positive can be achieved by considering only those samples as ANCA positive that test positive both on IIF and ELISA and by following ordering guidelines before requesting ANCA testing, and by use of ordering criteria by clinicians.

Emergency testing for antineutrophil cytoplasmic antibodies combined with a dialog-based policy between clinician and biologist: effectiveness for the diagnosis of ANCA-associated vasculitis

A prompt immunosuppressive treatment initiation is crucial in ANCA-associated vasculitis (AAV) to minimize organ injury. The aim of the present work was to analyze the accuracy of emergency ANCA screening to identify rapidly patients with AAV. In our Institution, emergency ANCA screening is based on a telephone call between a Clinician and a Biologist. Indirect immunofluorescence (IIF) for ANCA detection was performed using a commercial kit (Euroimmun(®) Granulocyte Mosaic 12). Positive serums for c- or p-ANCA at IIF are subsequently screened for antigenic specificity (MPO or PR3) by an immunodot technique (immunodot, D-Tek(®).) Positive samples with atypical c- or p-ANCA pattern at IIF are subsequently screened for antigenic specificity by ELISA. Data were retrieved from patients' medical records and confronted to emergency ANCA screening results. Between 2005 and 2012, 114 patients were screened. IIF was positive in 27.2% of patients, but c-/p-ANCA anti-MPO/-PR3 was detected in 13.2% of patients. The sensibility and specificity of IIF combined with immunodot for newly diagnosed AAV were 83.3 and 100%, respectively. Ten patients were newly diagnosed with AAV. In these patients, a specific AAV treatment was initiated less than 24 h following ANCA screening. Emergency ANCA screening based on a clinical gating policy was relevant to identify patients with AAV diagnosis, and was associated with a rapid treatment initiation.

State of the art in the treatment of systemic vasculitides

Anti-neutrophil cytoplasm antibodies (ANCA) are associated with small vessel vasculitides (AASV) affecting the lungs and kidneys. Structured clinical assessment using the Birmingham Vasculitis Activity Score and Vasculitis Damage Index should form the basis of a treatment plan and be used to document progress, including relapse. Severe disease with organ or life threatening manifestations needs cyclophosphamide or rituximab, plus high dose glucocorticoids, followed by lower dose steroid plus azathioprine, or methotrexate. Additional plasmapheresis is effective for very severe disease, reducing dialysis dependence from 60 to 40% in the first year, but with no effect on mortality or long-term renal function, probably due to established renal damage. In milder forms of ANCA-associated vasculitis, methotrexate, leflunomide, or mycophenolate mofetil are effective. Mortality depends on initial severity: 25% in patients with renal failure or severe lung hemorrhage; 6% for generalized non-life threatening AASV but rising to 30–40% at 5 years. Mortality from GPA is four times higher than the background population. Early deaths are due to active vasculitis and infection. Subsequent deaths are more often due to cardiovascular events, infection, and cancer. We need to improve the long-term outcome, by controlling disease activity but also preventing damage and drug toxicity. By contrast, in large vessel vasculitis where mortality is much less but morbidity potentially greater, such as giant cell arteritis (GCA) and Takayasu arteritis, therapeutic options are limited. High dose glucocorticoid results in significant toxicity in over 80%. Advances in understanding the biology of the vasculitides are improving therapies. Novel, mechanism based therapies such as rituximab in AASV, mepolizumab in eosinophilic granulomatosis with polyangiitis, and tocilizumab in GCA, but the lack of reliable biomarkers remains a challenge to progress in these chronic relapsing diseases.

Current and emerging techniques for ANCA detection in vasculitis

Detection of antineutrophil cytoplasmic antibodies (ANCAs) is a well-established diagnostic test used to evaluate suspected necrotizing vasculitis of small blood vessels. Conditions associated with these antibodies, collectively referred to as ANCA-associated vasculitides, include granulomatosis with polyangiitis (formerly known as Wegener granulomatosis), microscopic polyangiitis, and eosinophilic granulomatosis with polyangiitis (formerly known as Churg-Strauss syndrome). The diagnostic utility of ANCA testing depends on the type of assay performed and on the clinical setting. Most laboratories worldwide use standard indirect immunofluorescence tests (IFT) to screen for ANCA and then confirm positive IFT results with antigen-specific tests for proteinase 3 (PR3) and myeloperoxidase (MPO). Developments such as automated image analysis of immunofluorescence patterns, so-called third-generation PR3-ANCA and MPO-ANCA ELISA, and multiplex technology have improved the detection of ANCAs. However, challenges in routine clinical practice remain, including methodological aspects of IFT performance, the diverse antigen-specific assays available, the diagnostic value of testing in clinical settings and the prognostic value of serial ANCA monitoring in the prediction of disease relapse. This Review summarizes the available data on ANCA testing, discusses the usefulness of the various ANCA assays and advises on the clinical indications for the use of ANCA testing.

The role of the physician in laboratory medicine: a European perspective

Advances in medical laboratory technology have driven major changes in the practice of laboratory medicine over the past two decades by the development of automated, cross-disciplinary single platform analysers. This has led to the blurring of boundaries between traditional disciplines and the emergence of core automated or blood science laboratories. This paper was commissioned by the Union of European Medical Specialists to examine the changing role of laboratory-based physicians in the light of these advances by focusing on the added value of expert interpretation of test results and resultant improvements in clinical outcomes. The paper also considers the broad range of responsibilities of laboratory-based physicians and the difficulties in precisely measuring how this translates into improved clinical outcomes. Given its provenance, the paper concentrates predominantly on the role of laboratory-based physicians while acknowledging the essential and vital role of scientists in running diagnostic laboratory services.

ANCA testing: the current stage and perspectives

During the past 30 years, remarkable progress has been achieved in understanding the role of the antineutrophil cytoplasmic antibodies (ANCAs) directed against proteinase 3 (PR3) and myeloperoxidase (MPO) in so-called "ANCA-associated vasculitides". In the right clinical context, ANCAs are a good seromarker for these diseases, have improved nomenclature of systemic vasculitides and have contributed to new pathogenic concepts. However, problems with the clinical applications of ANCA testing in daily practice remain. They can be summarised as follows: assay standardisation and performance; the use of ANCA testing in a clinical setting with a low pretest probability; the relationship between ANCA titres and disease activity remains unclear. The solution to problems regarding the ANCA diagnosis is focussed on the fundamental methods, i.e., correct implementation of IFT and ELISA, the cautious use of commercial assays and restricting the use of the tests to clinical situations with a rather high pretest probability of AAV.

Antineutrophil cytoplasm autoantibodies: usefulness in rheumatology

The primary vasculitidies are complex diseases with varied clinical manifestations, which may be common to those present in multiple diseases. The antineutrophil cytoplasm autoantibodies (ANCA) led to a revolution in the diagnosis and research of these diseases, being the first and so far, the only biomarkers for three of these diseases, which affect small caliber vessels. From their description, much progress has been made, but there are still gray or misunderstood areas regarding their best use in the clinic. This can lead to errors as making a positive test synonym for vasculitis, or to overestimation of its importance. This review will address aspects such as nomenclature, employment in the diagnosis and monitoring of vasculitis, their presence in other diseases, their methods of detection, and finally, some comments on other potential biomarkers in vasculitis.