PREVALENCE AND MANAGEMENT OF GLOMERULONEPHRITIS AND VASCULITIS CAUSED BY ANTI-NEUTROPHIL CYTOPLASMIC ANTIBODIES: A CROSS-SECTIONAL STUDY IN A SECONDARY HOSPITAL
Da Cruz, M. 1
Zarcos Palma, N. 1
Couto, C. 1
Vasconcelos, G. 1
Santos, L. 1
Cruz, M. 1
Meireles, R. 1
Botelho, C. 2
1 Internal Medicine Department Centro Hospitalar Tâmega e Sousa, E.P.E.
2 Nephrology Department, Centro Hospitalar Tâmega e Sousa, E.P.E.
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Los procesos vasculíticos afectan el riñón, con frecuencia particularmente aquellos que afectan a los vasos pequeños, se han descrito muchas entidades, que se caracterizan por la ausencia/escasez de depósitos inmunes a la microscopía de inmunofluorescencia y se asocian con anticuerpos citoplasmáticos de neutrófilos(ANCA).
Caracterizar retrospectivamente la vasculitis pauci-inmune en pacientes con vasculitis pauci-inmune ingresados y ambulatorios.
Estudio retrospectivo, transversal. Analizamos a todos los pacientes diagnosticados con glomerulonefritis (GN) y vasculitis causada por anticuerpos citoplasmáticos antineutrófilos (ANCA) en el momento del estudio.
se estudiaron 12 pacientes. La edad media fue de 54 años y el 68% eran mujeres. La presentación clínica más frecuente fue afectación renal y pulmonar. La creatinina sérica media fue de 4,3±2,5 mg/dL. Siete tenían proteinuria <1g, 3 entre 1-3.5g y 2 pacientes>3.5g/dia. Serologías: ANCA-P-MPO (n=8); ANCA-C-PR3 (n=2); Anti-MBG y ANCA-P-MPO (n=1), y todos negativos (n=1). Las biopsias renales mostraron crecientes glomerulares bajo microscopía óptica. Todos los pacientes fueron tratados con corticosteroides y ciclofosfamida. 2 pacientes necesitaban hemodiálisis y 2 incluso plasmaféresis. Durante el período de seguimiento, todos alcanzaron la remisión. 1 progresó a enfermedad renal crónica terminal y nadie murió. Hubo 2 complicaciones infecciosas durante el seguimiento que condujeron a la hospitalización.
El sexo femenino y la afectación pulmonar-renal son más prevalentes en la presentación clínica inicial. Solo 2 pacientes requirieron hemodiálisis y plasmaféresis en la fase aguda. Hasta la fecha, no ha habido mortalidad, no se han detectado complicaciones relacionadas con la enfermedad y ha habido una baja proporción de complicaciones relacionadas con el tratamiento.
Palabras Clave: glomerulonefritis, vasculitis asociada a anticuerpos anti-neutrófilos, vasculitis pauciinmune.
Vasculitic processes frequently affect the kidney, particularly those affecting small vessels, many entities have been described, which are characterized by the absence/scarcity of immune deposits to immunofluorescence microscopy and are frequently associated with neutrophil cytoplasmic antibodies (ANCA).
To retrospectively characterize pauci-immune vasculitis in in-patients and out-patients with pauci-immune vasculitis.
Retrospective, cross-sectional study. We analysed all patients diagnosed with Glomerulonephritis (GN) and vasculitis caused by anti-neutrophil cytoplasmic antibodies (ANCA) within the time of the study.
12 patients were studied. Mean age was 54 years old and 68% were female. The most frequent clinical presentation was renal and pulmonary involvement. Mean serum creatinine was 4.3±2.5 mg/dL. Seven had proteinuria <1g, 3 between 1-3.5 g and 2 patients >3.5g/dia. Serologies were: ANCA-P-MPO (n=8); ANCA-C-PR3 (n=2); Anti-MBG and ANCA-P-MPO (n=1), and all negative (n=1). Renal biopsies showed glomerular crescents under light microscopy. All patients were treated with corticosteroids and cyclophosphamide. 2 patients needed hemodialysis and 2 still had plasmapheresis. During the follow-up period all reached remission. 1 progressed to terminal chronic kidney disease and no one died. There were 2 infectious complications during the follow up that led to hospitalization.
Female and pulmonary-renal involvement are more prevalent at the initial clinical presentation. Only 2 patients required hemodialysis and plasmapheresis in the acute phase. To date, there has been no mortality, no disease-related complications have been detected, and there has been a low ratio of treatment-related complications.
Keywords: Glomerulonephritis, anti-neutrophil antibody-associated vasculitis, pauci-immune vasculitis
Glomerulonephritis (GN) and vasculitis caused by anti-neutrophil cytoplasmic antibodies (ANCA) is the most common form of new-onset GN in adults older than 50 years old, although it can occur at any age, with equal distribution between genders 1. There are racial / ethnic and geographic factors influencing the prevalence, serotype and phenotype. In the European population, the incidence is reported to be 1-2 cases/ 100 000, with an increasing trend up to 2000 2.
The 2012 Chapel Hill Consensus Conference Nomenclature of Vasculitides (CHCC) defines ANCA-associated vasculitis as necrotizing vasculitis, with few or no immune deposits, predominantly affecting small vessels (capillaries, venules, arterioles, and small arteries) 3. Pauci-immune necrotizing GN, which is characterized by the paucity of staining for immunoglobulins by immunofluorescence, and crescentic GN, with 50% or more glomeruli being involved with crescents, is the typical pattern of glomerular injury in all forms of systemic ANCA-associated vasculitis. It may occur as a renal-limited disease or as a component of systemic necrotizing small-vessel vasculitis 4.
ANCA GN and vasculitis are defined by distinct pathologic lesions and an associated autoimmune response that produces ANCAs. ANCA vasculitis is associated with ANCA specific for myeloperoxidase (MPO-ANCA) or proteinase 3 (PR3-ANCA). Based on clinical and pathological features, the ANCA GN and vasculitis are divided in: microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA), formerly Wegener, and eosinophilic granulomatosis with polyangiitis (EGPA), formerly Churg–Strauss, as well as renal-limited vasculitis (RLV) with pauci-immune necrotizing GN alone with no evidence for systemic vasculitis 3. The serotype should be specified in the diagnosis, along with the clinicopathological classification since the combination of both is useful for predicting prognosis and response to treatment 5. Prompt diagnosis and initiation of appropriate immunosuppressive therapy is essential for optimum patient and renal outcomes.
Clinical presentation of patients with GPA and MPA is unspecific. The presentation can be slowly over months or even years. These entities commonly present with constitutional symptoms may last for weeks to months without specific organ involvement 6.
Ear, nose, and throat (ENT) manifestations are more frequent in GPA (90% of estimated frequency) but can also occur in MPA (35% of estimated frequency) 7. Bone and cartilage destruction resulting in a saddle nose deformity, masses of the upper airway and cranial nerve entrapment is more typical of GPA 8. Both diseases may have airway or pulmonary parenchyma involvement associated to tracheal or subglottic stenosis, pulmonary consolidation, and/or pleural effusion. Pulmonary fibrosis and pulmonary arterial hypertension can also be present 9. Variable signs can be found in chest radiograph, most commonly include nodules, patchy or diffuse opacities and fleeting pulmonary infiltrates, and hilar adenopathy 10.
Renal involvement is common in GPA and MPA: glomerulonephritis presents with asymptomatic hematuria. A rise in serum creatinine may occur, and a variable degree of proteinuria, that is usually subnephrotic, can also be present 7.
Skin lesions may occur in 50% of the patients, the most common being purpura involving the lower extremities 11. Ophthalmic and orbital manifestations include eye pain, foreign body sensation, visual disturbance, diplopia, and proptosis 12.
In patients with clinical features of GPA/MPA and a positive ANCA test, suggesting vasculitis, histologic examination of an affected organ should be performed as soon as possible, to establish a diagnosis 13. Since a variety of diseases can present with similar clinical features or with positive ANCA serologies distinction of GPA/MPA from other systemic rheumatic diseases is frequently a clinical problem 14.
Eosinophilic granulomatosis with polyangiitis (EGPA), formerly Churg-Strauss, stands for a rather different syndrome. It is a multisystem disease manifested by allergic rhinitis, asthma, granulomatous inflammation in the lung and peripheral blood eosinophilia (>10%) 15. The precise etiology is yet unknown, ANCA are detected from 40% to 60% of patients 16. Other abnormalities in immunologic function, such as: heightened Th1 and Th2 lymphocyte function, increased eosinophil recruitment and decreased eosinophil apoptosis are present in this disease 17. Genetic factors may also play a role 19. Renal involvement is less common and less severe in this category, neuropathy and cardiac disease: coronary arteritis and myocarditis are more frequent, and main causes of morbimortality, accounting for 50 % of deaths 20.
Immunosuppressive therapy aims to induce remission, defined as stabilization or improvement of kidney function and all other organ specific vasculitic manifestations. Inadequate or no response to therapy is considered treatment resistance. Patients achieving remission, either complete (without immunosuppressive therapy) or on therapy, may or may not experience one or more relapses afterwards 21. Conventional treatment of ANCA associated vasculitis with major organ involvement has been high dose cyclophosphamide or rituximab and glucocorticoids, which has induced remission in 90% of patients at 6 months, although, relapses and side effects are common 22. Selected patients with severe disease may benefit from the addition of plasma exchange.
Maintenance of remission with immunosuppressive and glucocorticoids tapered to the lowest possible dose is set for a variable period to prevent relapse. Prompt diagnosis is important to permit initiation of therapy that may be lifesaving and organ sparing 8.
Materials and Methods
We conducted a retrospective, cross-sectional study of all patients diagnosed with Glomerulonephritis (GN) and vasculitis caused by anti-neutrophil cytoplasmic antibodies (ANCA) according to the International Classification of Diseases, 10th Edition (ICD.10.CM, codes M30.1, N08.5). We analysed all patients with identified ANCA GN and vasculitis, admitted to the Tâmega e Sousa Hospital Center - Hospital de Penafiel between 05.2014 and 12.2015.
A self-developed form was used for collecting information about the patients from the individual medical record. To ensure anonymity, alphanumeric codes were used to identify the patients.
The patient recruitment was performed in collaboration between Nephrology and Internal Medicine. We included only patients with documented pauci-immune vasculitis. In each patient, a biopsy had been performed to confirm the diagnosis. Data were abstracted from the hospital charts. Variables included were age, gender, ethnicity and clinical presentation.
Diagnostic tests were included in study protocol, on admission and on follow-up. Acute renal insufficiency was defined as an increase of at least 30% of baseline serum creatinine in <3 months. The glomerular filtration rate (GFR) was calculated using the Cockcroft–Gault formula, considering the highest initial creatinine at diagnosis and the latest available creatinine value during follow-up. Nephrotic syndrome was defined as proteinuria >3.5 g/day and a serum albumin < 30 g/L. Arterial hypertension was defined as a blood pressure > 140/90mmHg or if antihypertensive medication was needed. MPA, GPA, EGPA and RLV were diagnosed according to the Chapel-Hill consensus conference criteria. For classification purposes, chest and/or sinus X-ray results were evaluated from all patients. Additionally, the results of any biopsy of extra-renal organs were considered.
Immunological data was performed at initial clinical presentation and was obtained regularly during follow-up. Tests for anti-MPO and anti-PR3 antibodies were performed in all available blood samples by enzyme-linked immunosorbent assay. All patients had periodic follow-up and their outcome was investigated.
The data collected constitute a sample of non-probabilistic convenience.
Continuous variables are expressed as the mean (standard deviation) or median (interquartile range) if the distribution is skewed; categorical data is expressed as counts and proportions. Data was stored and analysed using SPSS version 23.0.
Twelve patients were evaluated (8 were female (67%) and 4 were male (33%)) F / M-2 ratio, with mean age of 54.2 ± 13 years at presentation table 1.
The majority of patients presented with acute renal insufficiency (7 out of 12 patients). Five of them showed acute renal failure with a creatinine >3,5 mg/dL; two required short-term hemodialysis at diagnosis. Median serum creatinine at presentation was 4,3 +/- 2,5 mg/dL. Microhematuria was present in all cases. The median level of proteinuria was 2,8 g/day. Nephrotic syndrome was present in 2 cases. All patients were hypertensive.
All patients showed constitutional symptoms of vasculitis including fatigue, night sweats, weight loss and fever. Clinical signs of vasculitic skin involvement was observed in 1 case, proven by skin biopsy. Pulmonary infiltrates revealed by X-ray were seen in 8 cases. Two patients required plasmapheresis due to pulmonary hemorrhage. Ischemic bowel disease was present in 1 patient.
MPA was diagnosed in 5 out of 12 patients. 3 patients were classified as GPA. 2 patients were diagnosis with EGPA and two patients as RLV.
ELISA tests for anti-MPO and anti-PR3 were negative in one patient. ANCA-MPO were positive in 8 patients, ANCA-PR3 were positive in 2 patients. One patient had positivity for ANCA-MPO and Anti-Glomerular basal membrane (GBM).
Ten patients underwent renal biopsy, 8 of which had glomerular crescents under light microscopy.
All patients received a primary immunosuppressive protocol with intravenous and oral steroids, and cyclophosphamide pulse therapy. Two patients had plasma exchange. During the acute phase 2 patients started hemodialysis, having partially recovered renal function. After a period of 6 months, cyclophosphamide was substituted by azathioprine in all patients.
All of the studied patients survived during the follow-up.
Only one patient progressed to end-stage renal failure. During the follow-up period (16 ± 13 months), none of the patients manifested reactivation of the disease.
There were 2 infectious complications during follow-up period that led to hospitalization both pneumonias.
The vasculitis are life‐threatening conditions whose destructive nature has long been acknowledged 23. Anti-neutrophil cytoplasmic antibody was first reported in 1982 in patients with segmental necrotizing glomerulonephritis on biopsy and absent or scant, irregular deposits by direct immunofluorescence 24. The etiology of most cases of ANCA-positive pauci-immune glomerulonephritis remains unknown 25.
Pauci-immune crescentic glomerulonephritis is the most common cause of aggressive glomerulonephritis  and it is more frequent in older patients as seen in large series 26. Our results are in line with the literature with a median age of 54.2 ± 13 years, all Caucasian individuals. Equal distribution between genders 27 is seen in most series in Western countries, some show a male female ratio of 0.95:1 in ANCA negative GN 26, our ratio male female ratio is 1:2, this fact is probably due to the dimension of the studied sample.
In Southern Europe MPA is more common than GPA and the latter more frequent that EGPA and RLV 28. This distribution was the one observed in our cases.
Pauci-immune glomerulonephritis may present with different clinical scenarios. In our series clinical or pathological evidence of renal disease was present in 100% of the analysed sample, in literature it was observed 28 in approximately 90% of patients with MPA, 80% of patients with GPA and 45% of patients with EGPA 16, 10, 26. In this series none of the patients was diagnosed with EGPA, due to the superior prevalence of renal disease.
MPA, GPA and EGPA share certain clinical features, but each also has distinctive characteristics 29, 1, 14.
In this case series 8 out of 12 had, as extra-renal involvement, pulmonary disease, common manifestations of GPA or MPA. Patients presented with dyspnea, hemoptysis and/or pleuritic pain. Pulmonary hypertension and fibrosis can be found in such patients, although none of them was seen in this series. Chest radiography had variable findings, such as: hilar adenopathy, diffuse opacities and fleeting pulmonary infiltrates. Skin and Gastro-intestinal disease was rare.
ANCA, were first reported by Davies et al. 24, are antibodies specific for proteins in the cytoplasmic granules of neutrophils and the lysosomes of monocytes. Two major specificities for ANCA are distinguished on the basis of cytoplasmic (cANCA) or perinuclear (pANCA) ANCA staining by indirect immunofluorescence microscopy and by enzyme immunoassay demonstrating anti-myeloperoxidase (MPO-ANCA) and anti-proteinase 3 (PR3-ANCA). Approximately 90% of cytoplasmic ANCA are PR3-ANCA, and approximately 90% of perinuclear ANCA are MPO-ANCA.
Patients with GPA usually have cANCA (PR3-ANCA), patients with MPA have slightly more pANCA (MPO-ANCA), and patients with EGPA and renal-limited AAV have predominantly pANCA (MPO-ANCA) 14.
More importantly, ANCA specificity was shown to be strongly associated with organ involvement and distinct clinical pictures of pauci-immune vasculitis. Specifically, patients with kidney-limited disease or any form of vasculitis without radiological or histological proof of granulomatous inflammation were more likely to have MPO-ANCA, and those with evidence for necrotizing granulomatous inflammation were more likely to have PR3-ANCA 1. This trend was present in our series as can be seen in table 1.
The hallmark histological lesions of acute pauci-immune glomerulonephritis are crescents and fibrinoid necrosis occurring with the same frequency, irrespective of the presence or absence of associated vasculitis 30, the severity of acute lesions ranges from focal segmental fibrinoid necrosis affecting <10% of glomeruli to severe diffuse necrotizing and crescentic glomerulonephritis, which may injure all glomeruli. The extent of crescent formation does not differ between patients with PR3-ANCA or MPO-ANCA, breaks in Bowman’s capsule are common 31.
The treatment scheme adopted in this series was the gold standard treatment: combination of corticosteroids with the cytotoxic agent cyclophosphamide (intravenous pulses of methylprednisolone (7 mg/kg body weight for 3 consecutive days), followed by oral prednisone (1 mg/kg body weight for the first 4 weeks), reduced in a gradual and personalized manner, and Cyclophosphamide was given orally at an initial dose of 2 mg/kg/day, always adjusted on the basis of the patient’s leukocyte count and the current glomerular filtration rate. Duration of therapy with cyclophosphamide is usually 6–12 months, depending on the patient’s initial response) 35, 51. Both oral and intravenous administrations of cyclophosphamide have been proven equally potent inductors of remission. In this series the patient used the oral form of the cytotoxic agent to induction therapy.
The authors describe two diffuse alveolar hemorrhages, presenting with hemoptysis and pulmonary opacities along with glomerulonephritis, these patients initiated promptly plasmapheresis therapy coupled with aggressive immunosuppression. Such therapy was in these cases, lifesaving, although renal function recovery is less certain 32. One of them evolved to terminal chronic kidney disease with need of chronic hemodialysis. Although all of the patients presented acute kidney injury, only two required short-term hemodialysis at diagnosis
The majority of patients usually attain remission 6, in this sample 100% achieved it.
The use of cytotoxic drugs and corticosteroids has resulted in patient outcome improvement, with modest treatment toxicity and few treatment-related deaths 34, with tight follow-up, patient empowerment leading to a timely diagnosis, only 2 patients and infectious complications with need to hospitalization, both pneumonias.
It is important to note the limitations of our series, the retrospective follow-up is the major flaw of our study: depending on data extracted from medical records, we could not assess the prognostic value of several other factors at diagnosis (thrombocyte count, IgG level, ANCA titer) and during the follow-up (relapse rate, use of ACE inhibitors, occurrence of leukopenia and sepsis, type and duration of maintenance therapy).
A second limitation with the study is the monocentric nature of the cohort, which raises some questions about how tenable any generalization would be. However, as with any rare disorder, sufficient patient numbers for optimal studies are lacking.
Prompt diagnosis requires an appropriate index of suspicion, familiarity with the broad range of presenting symptoms and signs, and the knowledge required to accurately distinguish ANCA vasculitis and GN from vasculitis. Optimum treatment requires an understanding of the implications on treatment regimens of different serotypes, different clinicopathologic phenotypes, and different degrees of activity, chronicity, and severity . We believe this report can be helpful in remembering the updated classification system and emphasizing that early diagnosis and timely immunosuppressive therapy are fundamental.