Rheumatoid factor false positivity in patients with ANCA-associated vasculitis not having medical conditions producing rheumatoid factor

Progression to ANCA-associated vasculitis in patients with idiopathic interstitial pneumonia and positive ANCA

OBJECTIVE

This study explored the development of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and its risk factors in patients with idiopathic interstitial pneumonia (IIP) and positive ANCA results.

METHODS

Data of patients diagnosed with IIP with positive ANCA results at a single tertiary center in South Korea were retrospectively reviewed from January 2013 to August 2023. Cox regression analysis was performed to identify variables associated with AAV occurrence following IIP diagnosis. Kaplan-Meier curves were employed to investigate the relationship between autoantibodies and the occurrence of AAV.

RESULTS

In a cohort of 154 IIP-diagnosed patients with positive ANCA results but without AAV, 10.4 % of them eventually developed AAV. The AAV and non-AAV groups did not significantly differ by sex, age, smoking status, urinalysis, or chest computed tomography findings. All the patients who subsequently developed AAV were anti-myeloperoxidase (MPO) positive, while 48.8 % of the non-AAV patients were anti-MPO positive (P < 0.001). Rheumatoid factor (RF) positivity differed significantly (62.5 % vs. 29.2 %, P = 0.007) between the AAV and non-AAV groups. Multivariate Cox regression and Kaplan-Meier analyses revealed RF (HR 4.02; P = 0.004) and anti-MPO (HR 38.10; P < 0.001) positivity as risk factors associated with AAV occurrence.

CONCLUSION

Approximately 10 % of ANCA-positive IIP patients developed AAV after an IIP diagnosis. Anti-MPO or co-occurring positive RF poses a significant risk for subsequent AAV occurrence. This emphasizes the importance of careful monitoring in patients with high-risk antibody profiles, even if the complete features of AAV are not present at IIP diagnosis.

The role of blood testing in prevention, diagnosis, and management of chronic diseases: A review

Blood tests are vital to prevention, diagnosis, and management of chronic diseases. Despite this, it can be challenging to construct a comprehensive view of the clinical importance of blood testing because relevant literature is typically fragmented across different disease areas and patient populations. This lack of collated evidence can also make it difficult for primary care providers to adhere to best practices for blood testing across different diseases and guidelines. Thus, this review article synthesizes the recommendations for, and importance of, blood testing across several common chronic conditions encountered in primary care and internal medicine, including cardiovascular diseases, diabetes mellitus, chronic kidney disease, vitamin D deficiency, iron deficiency, and rheumatoid arthritis. Future research is needed to continue improving chronic disease management through clearer dissemination and awareness of clinical guidelines among providers, and better access to blood testing for patients (e.g., via pre-visit laboratory testing).

The assessment of rheumatoid factor levels and hemogram parameters as predictors for rheumatologic disease

AIM

Many markers are used for clinical diagnosis in rheumatic diseases; rheumatoid factor (RF) is the most frequently used marker. However, RF is not specific to rheumatoid arthritis (RA). RF positivity is widely observed in patients with advanced age, infectious, autoimmune, and lymphoproliferative diseases. In this context, the objective of this study is to investigate the demographic characteristics, frequency of antinuclear antibody (ANA) and anti-cyclic citrullinated peptide (anti-CCP) positivity, hemogram parameters and distribution of the diagnoses in RF-positive patients followed at the rheumatology clinic.

METHODS

The population of this retrospective study consisted of patients above 18 years of age who were referred to have RF positivity by nephelometric method at Kahramanmaraş Necip Fazıl City Hospital Rheumatology Clinic between January 2020 and June 2022.

RESULTS

The mean age of the 230 patients with a positive RF test result, 155 (76%) male and 55 (24%) female, was 52.7 ± 15.5 years. There were 81 (35.2%), 54 (23.5%), 73 (31.7%) and 22 (9.6%) patients with RF levels between 20 and 50 IU/mL, 50 and 100 IU/mL, 100 and 500 IU/mL, and above 500 IU/mL, respectively. There was no significant difference detected between the groups that were created based on the RF titers regarding demographic characteristics (P > 0.05). The rate of being diagnosed with any rheumatic disease was significantly lower in the group with RF levels between 20 and 50 IU/mL compared to other groups (P = 0.001). The distribution of rheumatic and non-rheumatic disease diagnoses according to RF levels did not reveal any significant difference between the groups (P = 0.369 and P = 0.147, respectively). RA was the most common (62.2%) rheumatic disease diagnosis among the patients included in the study. The leukocyte count was significantly higher in the group with RF levels above 500 IU/mL compared to the group with RF levels between 20 and 50 IU/mL (P = 0.024). There was no significant difference between the groups in other laboratory results, that is, hemogram, sedimentation, C-reactive protein, platelet, and lymphocyte/monocyte ratio (P > 0.05).

CONCLUSION

The study findings indicate that RF positivity can be seen in the context of different rheumatological diseases; hence RF levels alone may not predict rheumatological disease. There was also no significant relationship between RF levels and ANA and anti-CCP positivity. The most common diagnosis in patients presenting with elevated RF levels was RA. Nevertheless, it should be noted that RF can be found asymptomatically in the general population.

Antineutrophil cytoplasmic antibodies in infective endocarditis: a case report and systematic review of the literature

Infective endocarditis (IE) may be misdiagnosed as ANCA-associated vasculitis (AAV), especially when antineutrophil cytoplasmic antibodies (ANCA) are detected. Distinguishing IE from AAV is crucial to guide therapy. However, little is known about ANCA positivity in IE patients. We present a case report and systematic review of the literature on patients with ANCA-positive IE, aiming to provide a comprehensive overview of this entity and to aid clinicians in their decisions when encountering a similar case. A systematic review of papers on original cases of ANCA-positive IE without a previous diagnosis of AAV was conducted on PubMed in accordance with PRISMA-IPD guidelines. A predefined set of clinical, laboratory, and kidney biopsy findings was extracted for each patient and presented as a narrative and quantitative synthesis. A total of 74 reports describing 181 patients with ANCA-positive IE were included (a total of 182 cases including our own case). ANCA positivity was found in 18-43% of patients with IE. Patients usually presented with subacute IE (73%) and had positive cytoplasmic ANCA-staining or anti-proteinase-3 antibodies (79%). Kidney function was impaired in 72%; kidney biopsy findings were suggestive of immune complexes in 59%, while showing pauci-immune glomerulonephritis in 37%. All were treated with antibiotics; 39% of patients also received immunosuppressants. During follow-up, 69% of patients became ANCA-negative and no diagnosis of systemic vasculitis was reported. This study reviewed the largest series of patients with ANCA-positive IE thus far and shows the overlap in clinical manifestations between IE and AAV. We therefore emphasize that clinicians should be alert to the possibility of an underlying infection when treating a patient with suspected AAV, even when reassured by ANCA positivity. Key Points • This systematic review describes - to our knowledge - the largest series of patients with ANCA-positive infective endocarditis (IE) thus far (N=182), and shows a high degree of overlap in clinical manifestations between IE and ANCA-associated vasculitis (AAV). • ANCA positivity was found in 18-43% of patients with infective endocarditis. Of patients with ANCA-positive IE, the majority (79%) showed cytoplasmic ANCA-staining or anti-PR3-antibodies. We emphasize that clinicians should be alert to the possibility of an underlying infection when treating a patient with suspected AAV, even when reassured by ANCA positivity. • In patients with IE and ANCA-associated symptoms such as acute kidney injury, an important clinical challenge is the initiation of immunosuppressive therapy. All patients with data in this series received antibiotics; 39% also received immunosuppressive therapy. In many of these patients, ANCA-associated symptoms resolved or stabilized after infection was treated. ANCA titers became negative in 69% , and a diagnosis of AAV was made in none of the cases. We therefore recommend that (empiric) antibiotic treatment remains the therapeutic cornerstone for ANCA-positive IE patients, while a watchful wait-and-see approach with respect to immunosuppression is advised.

Rheumatoid factor positivity in antineutrophil cytoplasmic antibody-associated vasculitis: a distinct clinical entity or innocent bystander?

OBJECTIVE

To investigate the significance of rheumatoid factor (RF) positivity in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) patients.

METHODS

AAV patients were divided into groups as follows: RF (+)/ANCA (+) (n = 94), RF (-)/ANCA (+) (n = 80), RF (+)/ANCA (-) (n = 15), and RF (-)/ANCA (-) (n = 25). Their clinical data, organ involvement patterns, laboratory data, and patient outcomes were assessed. Kaplan-Meier analysis and propensity score matching (PSM) were performed to compare outcomes and analyse differences between the groups.

RESULTS

Of the 214 patients, RF and ANCA positivity was found in 109 (50.9%) and 174 (81.3%) patients, respectively. RF (+)/ANCA (+) patients more frequently presented with general manifestations (58.5%) than the other groups. Additionally, compared with those of RF (-)/ANCA (+) group, RF (+)/ANCA (+) patients were older, had higher white blood cell, neutrophil, platelet counts, and acute phase reactants; however, creatinine and albumin levels were lower. The end-stage kidney disease-free survival rate was significantly higher in the RF (+)/ANCA (+) group (p= 0.013), while the proportion of renal involvement was comparable to the RF (-)/ANCA (+) group. PSM showed no difference in patient outcomes between the two groups after adjustment.

CONCLUSION

RF positivity was associated with a distinct phenotype in AAV patients. In particular, difference was observed in clinical features and outcomes between RF (+)/ANCA (+) and RF (-)/ANCA (+) groups, although the direct prognostic implication of RF was not evident.

ANCA-Associated Vasculitis Clinical Presentation and Clinical Predictors of Relapse in Saudi Arabia

Background

Anti-neutrophil cytoplasm antibodies-associated vasculitis (AAV) is a rare autoimmune condition with high-relapsing rate and incidence of complications, resulting in increased morbidity and mortality. Characters of patients with anti-neutrophil cytoplasm antibodies-associated vasculitis in Saudi Arabia require further exploration.

Objective

To evaluate the clinical profile, relapse rate and disease-related complications among patients with AAV at a tertiary hospital in Saudi Arabia. To estimate the role of BVAS score at the time of presentation in predicting relapse during the disease course.

Design and Setting

This retrospective cohort study was performed through data collection from patients’ records who had AAV, who visited the rheumatology clinic. The collected data involved the demographics of patients and their investigations, medications, and outcomes of treatment. Statistical analysis was executed through SPSS version 26.

Results

Fifty-two patients were eligible for inclusion, while 48 patients were analyzed because of missing data. Females represented 60.4%. Half of the patients were more than 50 years old, and 68.8% had comorbidities. As for diagnosis, 62.5% had granulomatosis with polyangiitis, 25% had eosinophilic granulomatosis with polyangiitis, and 12.5% had microscopic polyangiitis. The rate of relapse was 31.3%, while the remission rate was 68.8%. Additionally, 66.7% had lower respiratory involvement, and 43.8% had renal involvement. More than half of the patients had BVAS score below 14.5 points. The study did not explore a positive correlation between the disease relapse and high BVAS at the first presentation.

Conclusion

Early prediction of relapse and such intervention is of paramount importance in order to avoid accrual of organ damage with treatments that prevent further relapses. BVAS score was not found to be a potential predictor in our study. Future studies are highly endorsed, with prospective design and large sample size to achieve statistical significance for the incidence of relapses and complications.

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.

Patients with ANCA-Associated Glomerulonephritis and Connective Tissue Diseases: A Comparative Study from the Maine-Anjou AAV Registry

BACKGROUND AND OBJECTIVES

The overlap between antineutrophil cytoplasmic antibody (ANCA) associated glomerulonephritis (ANCA-GN) and connective tissue diseases (CTD) has been reported mainly as case series in the literature. Frequency of this association, as well as presentation and outcomes are unknown.

MATERIALS AND METHODS

Patients from the Maine-Anjou ANCA-associated vasculitides (AAV) registry with ANCA-GN diagnosed between 01/01/2000 and 01/01/2018, ANCA positivity, and at least six months of follow-up, were included.

RESULTS

106 out of 142 patients fulfilled the inclusion criteria and were analyzed. CTD was present at ANCA-GN diagnosis in 16 (15.1%) patients. The most common CTD were rheumatoid arthritis, Sjogren syndrome and systemic sclerosis. Compared to the control group, females were more represented in the CTD group (75%, p = 0.001). Renal presentation was comparable between groups, including the pathological analysis of renal biopsies. Patients of CTD group presented a higher rate of non-renal relapse (25% versus 7.7%, p = 0.037), and experienced more frequently a venous thrombotic event (31.2% versus 10%, p = 0.021). No difference between groups was observed according to major outcomes.

CONCLUSION

Association between CTD and ANCA-GN is not a rare condition and predominantly affects females. While AAV presentation is not significantly different, CTD patients experience more frequently non-renal relapse and venous thrombotic events.

Subtypes in eosinophilic granulomatosis with polyangiitis classified according to rheumatoid factor

To investigate the relevance of RF in patients with EGPA, we reviewed consecutive patients who were newly diagnosed with EGPA from August 1998 to February 2019 in Keio University Hospital with RF titer at diagnosis available. We divided the patients according to the median level of RF titer of 75 IU/mL and compared clinical features between the two groups. Among 16 patients identified, 8 patients were in the RF high group and the other 8 patients were in the RF low group. All patients in the high RF group were negative for MPO-ANCA, whereas all in the low RF group was positive for MPO-ANCA with a mean titer of 103 IU/mL. The eosinophil count at diagnosis was significantly higher in the RF high group than the RF low group (20001/μL vs 5144/μL, p < 0.01). Gastrointestinal lesion was significantly more frequent in the RF high group, and parenchymal organ lesions, such as heart and renal organ involvement, were frequent in the RF low group. With principal component analysis, RF high and low groups were clearly divided by the combination of eosinophil count, MPO-ANCA titer, gastrointestinal lesions, musculoskeletal symptoms, and disease activity score. Those results suggest EGPA can be divided into two groups in association with RF.Key Points• Our study showed that patients with EGPA can be separated into two groups according to RF titer.• The two subtypes reflect different underlying pathogenesis in EGPA, and the optimal treatment for them may be different.

Antineutrophil Cytoplasmic Antibody-Associated Vasculitis in Korea: A Narrative Review

Antineutrophil cytoplasmic antibody-associated vasculitis (AAV) is a group of systemic necrotising vasculitides, which often involve small vessels, and which lead to few or no immune deposits in affected organs. According to clinical manifestations and pathological features, AAV is classified into three variants: microscopic polyangiitis, granulomatosis with polyangiitis (GPA), and eosinophilic GPA. The American College of Rheumatology 1990 criteria contributed to the classification of AAV, although currently the algorithm suggested by the European Medicines Agency in 2007 and the Chapel Hill Consensus Conference Nomenclature of Vasculitides proposed in 2012 have encouraged physicians to classify AAV patients properly. So far, there have been noticeable advancements in studies on the pathophysiology of AAV and the classification criteria for AAV in Western countries. However, studies analysing clinical features of Korean patients with AAV have only been conducted and reported since 2000. One year-, 5 year-, and 10 year-cumulative patient survival rates are reported as 96.1, 94.8, and 92.8%. Furthermore, initial vasculitis activity, prognostic factor score, age and specific organ-involvement have been found to be associated with either all-cause mortality or poor disease course. The rate of serious infection is 28.6%, and 1 year-, 5 year- and 10 year-cumulative hospitalised infection free survival rates range from 85.1% to 72.7%. The overall standardised incidence ratio of cancer in AAV patients was deemed 1.43 compared to the general Korean population.