Effects of smoking and shared epitope on the production of anti-citrullinated peptide antibody in a Japanese adult population. Terms and Conditions, In these cases, your doctor will need to factor in the severity of your symptoms, CRP and ESR, and imaging tests [27]. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. If the sample finds the presence of anti-CCP at a certain level, the result is positive. You must consult your doctor before acting on any content on this website, especially if you are pregnant, nursing, taking medication, or have a medical condition. MAMvd and LAT evaluated citrullination dependency by ELISA. The present results revealed that anti-CCP-positive non-RA CTD patients rarely developed RA. Ann Rheum Dis. The Mann-Whitney U test was used to analyze absorbance difference between anti-CCP and anti-CAP patients. Associations between genetic factors, tobacco smoking and autoantibodies in familial and sporadic rheumatoid arthritis. Doctors use the anti-CCP antibody test to help diagnose rheumatoid arthritis and determine if more aggressive treatment is needed to address the disease. Use. (4,6,10) A systemic review and meta-analysis of 33 studies including patients with RA and healthy or disease controls demonstrated the sensitivity of anti-mutated citrullinated vimentin, anticyclic citrullinated peptide, and RF of 71%, 71%, 77%, with the specificity of 89%, 95%, 73%, and the area under the curve of the summary receiver operating characteristic of 89%, 95%, 82%, respectively. Ann Rheum Dis. Yamaguchi M, Ohta A, Tsunematsu T, Kasukawa R, Mizushima Y, Kashiwagi H, et al. Correspondence to Lets look at how doctors use this test as an auto-immune marker. Testing for anti-CCP antibodies helps doctors to diagnose RA patients and determine how severe the disease is, as well as predict the likely outcome of the disease. In both patients with primary and SLE associated APS positive results correlate with a predisposition for arterial or venous thrombosis, foetal loss, or thrombocytopoenia. Growing up, he suffered from inflammation, brain fog, fatigue, digestive problems, insomnia, anxiety, and other issues that were poorly understood in traditional healthcare. Additionally, anti-CCP antibodies have been shown to be predictive of the progression of patients, indicating more . Aletaha D, Neogi T, Silman AJ, et al: 2010 Rheumatoid arthritis classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative. 2018 Nov;70(11):1721-1731, 10. CT, KM, RN, MH, YI, NY, HY, YM, KY, TM, TF, TMi, and KO contributed to the collection of samples and/or data. Citrullination dependency was evaluated by an in-house ELISA, the HLA-DRB1 allele was typed, and the results obtained were then compared between RA-overlapping and non-RA anti-CCP-positive CTD patients. Patients presenting with mono or pauciarticular pain of large joints with positive anti CCP antibody assay have to be investigated to rule out the possibility of early stage of tubercular arthritis before labeling them as of rheumatoid arthritis. Your immune system normally makes antibodies to help you fight infection. It affects about 0.6% of the US population with a global prevalence of 0.24%. The concentration of CCP antibodies is determined by comparison to a 5-point standard curve (15.6-250 U). Re-testing later on may be required in . 2008;1143:26885. A positive result for cyclic citrullinated peptide (CCP) antibodies indicates a high likelihood of rheumatoid arthritis (RA). Currently, they are not widely used in clinical practice [22]. 10 were positive for anti-2GPI antibodies (34.5%, 2 IgG, 5 IgM, 3 IgG+IgM) and 1 was positive for anti-CCP antibodies (3.5%). The entire, 55-min procedure for the detection of RF and anti-CCP using a dual-target ELISA assay is shown schematically in Fig. 2 We assessed isoagglutinin titers in a candidate for ABOi-living donor kidney transplantation (A to O) who was treated by a humanized anti-CD38 IgG monoclonal antibody (daratumumab) a week before for multiple myeloma. 2005;52(11):34338. Iwasaki, T., Nakabo, S., Terao, C. et al. They are continually monitored by our internal peer-review process and if we see anyone making material science errors, we don't let them write for us again. The substance to which this antibody reacts is cardiolipin, so the individuals with a false-positive syphilis test actually had a form of anticardiolipin antibodies. Knowing the symptoms of autoimmune joint disease is of utmost importance as well. Our goal is to not have a single piece of inaccurate information on this website. If you test positive for anti-CCP and are diagnosed with RA, your doctor will likely pursue a more aggressive treatment regimen. These patients may develop RA in the future because the emergence of anti-citrullinated protein antibodies (ACPA), including the anti-CCP antibody, precedes the onset of RA [3,4,5,6]. Follow-up of primary Sjogrens syndrome patients presenting positive anti-cyclic citrullinated peptides antibody. Rheumatoid arthritis is an autoimmune, inflammatory disorder caused by a person's immune system mistakenly attacking and destroying healthy cells within the body. 2012;64(8):267786. . We retrospectively investigated whether anti-CCP-positive non-RA CTD patients developed RA and attempted to identify factors that may differentiate RA-overlapping CTD from pure CTD. Autoantibodies can cause disease by attacking the body's healthy cells by mistake. 1987:417. Interpretation in the clinical context is important. The present results revealed that anti-CCP-positive non-RA CTD patients rarely developed RA. 2b). However, limited information is currently available on the long-term outcomes of anti-CCP-positive non-RA CTD patients. Despite the high specificity of the test, anti-CCP antibodies have also been observed in psoriatic arthritis. Cite 28th Dec, 2015 The test is also not used to screen for RA patients because it can frequently miss individuals who have the disease [14]. This indicates that anti-CCP Abs may be a helpful tool in the differential diagnosis of EORA from PMR. However, a large proportion of systemic sclerosis patients with the anti-CCP antibody developed erosive arthritis. Although we considered an anti-CCP titer 100 to be 100, the relationship between the anti-CCP antibody titer and the risk of developing RA is supported by patients with a high ACPA level having a high score in the 2010 ACR/EULAR classification criteria of RA [26] as well as a high anti-CCP antibody titer being more strongly associated with RA in the general population [32]. Ryu YS, Park SH, Lee J, Kwok SK, Ju JH, Kim HY, et al. Ann Rheum Dis. After further incubation and washing to remove unbound conjugate, substrate (3,3',5,5' tetramethylbenzidine) is added and allowed to incubate. If not ordering electronically, complete, print, and send a, Although late RA prognosis may be linked to adverse consequences, early diagnosis has been reported to improve outcomes; notably reduced joint destruction or deformity, delayed radiologic progression, and decreased functional disability. Arthritis Res Ther 22, 248 (2020). Two out of 33 anti-CCP-positive CTD patients (6.1%) developed RA during a mean follow-up period of 8.9years. (3-5), 2010 Rheumatoid arthritis classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative, Clients without access to Test Prices can contact, Prospective clients should contact their account representative. Evaluating the frequency of G6PD deficiency in blood donors found the prevalence was higher in donors with a positive family history, and the potentially severe consequences of a G6 PD hemolytic crisis may argue in favor of routine G 6PD screening of male blood donors in areas with high prevalence. Emery P, Breedveld FC, Dougados M, Kalden JR, Schiff MH, Smolen JS: Early referral recommendation for newly diagnosed rheumatoid arthritis: evidence based development of a clinical guide. Anti-CCP antibodies are found in most rheumatoid arthritis patients and likely play a key role in the development of the disease. These antibodies react with CAP, which is the arginine version of CCP (the citrulline residues of CCP were replaced by arginine). Anyone you share the following link with will be able to read this content: Sorry, a shareable link is not currently available for this article. Citrullination dependency was evaluated using an in-house ELISA at the Leiden University Medical Center, as described previously [27]. Even patients with Rheumatoid arthritis can have a positive ANA. Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website. Over the past 35 years, however, several additional antibodies have been isolated that are related to the scleroderma . An ANA test detects antinuclear antibodies (ANA) in your blood. 2a). Regarding anti-CCP-positive non-RA CTD patients who dropped out of the follow-up and RA-overlapped patients, we retrospectively evaluated X-rays of their hands and feet, which had been taken after the anti-CCP antibody became positive. (2) We evaluated only anti-CCP-positive patients and did not re-evaluate the serology of anti-CCP negative CTD patients, some of whom may have newly developed anti-CCP antibody. Clin Chem Lab Med. The test is ordered when a person displays signs and/or symptoms of rheumatoid arthritis. In addition to improving symptoms and preventing and reducing joint damage, these medications can reduce anti-CCP levels substantially [30, 31, 4]. Association between SARSCoV2 and SLE is not clear. Enzyme-Linked Immunosorbent Assay (ELISA). We simultaneously assessed anti-CAP and anti-CCP in 60 serum samples (33 RA-overlapping CTD and 27 non-RA CTD) and compared their reactivities. RMD Open. Arthritis Rheum. Article Shiboski SC, Shiboski CH, Criswell L, Baer A, Challacombe S, Lanfranchi H, et al. The detection of anti-CCP is useful for the diagnosis of RA because of its similar sensitivity but higher specificity compared with RF. Anti-CCP antibody titers were obtained from a retrospective chart review for 445 patients or were measured using the stored sera of 397 patients. Elsevier, Amsterdam. Aggarwal R, Liao K, Nair R, Ringold S, Costenbader KH. 2008;67(4):46670. The HLA-DRB1 allele was typed using the WAKFlow system (Wakunaga Pharmaceutical, Akitakata, Japan) and the following were classified as HLA-DRB1 SE: *01:01, *01:02, *04:01, *04:04, *04:05, *04:08, *04:10, *04:13, *04:16, *10:01, *13:03, *14:02, and *14:06, as reported previously [29]. Department of Rheumatology and Clinical Immunology, Graduate School of Medicine, Kyoto University, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto, Japan, Takeshi Iwasaki,Shuichiro Nakabo,Kosaku Murakami,Ran Nakashima,Hajime Yoshifuji,Takao Fujii,Tsuneyo Mimori&Koichiro Ohmura, Laboratory for Statistical and Translational Genetics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan, Clinical Research Center, Shizuoka General Hospital, Shizuoka, Japan, The Department of Applied Genetics, The School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan, Department of Advanced Medicine for Rheumatic Diseases, Graduate School of Medicine, Kyoto University, Kyoto, Japan, Department of Clinical Immunology and Rheumatology, Tazuke Kofukai Medical Research Institute, Kitano Hospital, Osaka, Japan, Department of Transfusion Medicine & Cell Therapy, Kyoto University Hospital, Kyoto, Japan, Yasuo Miura,Kimiko Yurugi&Taira Maekawa, Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands, Myrthe A. M. van Delft&Leendert A. Trouw, Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands, Department of Clinical Immunology and Rheumatology, Wakayama Medical University, Wakayama, Japan, Ijinkai Takeda General Hospital, Kyoto, Japan, You can also search for this author in The normal level of anti-CCP antibodies is less than 20 units/mL. Testing is performed on the Agility instrument by Dynex. The present study was supported in part by JSPS KAKENHI (grant no. Interpretation. Anti-CCP antibodies can be detected in RA patients years before they show any symptoms [19, 20]. In total, 842 CTD patients with a primary diagnosis that was not RA were selected from our CTD database as of December 2012. Google Scholar. 2002 Apr;61(4):290-297, 6. Frustrated by the lack of good information and tools, Joe decided to embark on a learning journey to decode his DNA and track his biomarkers in search of better health. it signifies and erosive subset of any arthritis. Ann Rheum Dis. This ANA testing method led to an increase in rheumatology referrals for RNP . (PPTX 48 kb). Bone erosions on the hands and feet were assessed by X-ray. Anti-CCP antibody testing usually requires that you have your blood drawn and sent to a lab. Anti-CCP or Anti-Cyclic Citrullinated Peptide is an autoantibody also known as ACPAs or anti-citrullinated protein antibodies. Thirty-nine out of the 62 RA-overlapping CTD patients tested positive for the anti-CCP antibody (62.9%). Ding B, Padyukov L, Lundstrom E, Seielstad M, Plenge RM, Oksenberg JR, et al. Rudwaleit M, Landew R, van der Heijde D, Listing J, Brandt J, Braun J, et al. We compared the clinical characteristics of 41 anti-CCP-positive RA-overlapping CTD patients (groups 1 and 2 in Fig. An asterisk denotes the accuracy of the diagnosis was reconfirmed by a questionnaire completed by each attending physician, which asked whether the patient fulfilled the 1987 revised ACR criteria for the classification of RA. Systemic lupus erythematosus (SLE): when active, usually a homogenous pattern on ANA or less commonly speckled, rim, or nucleolar when present in high enough titer to be . Manage cookies/Do not sell my data we use in the preference centre. statement and Low . A positive result for cyclic citrullinated peptide (CCP) antibodies may be suggestive of rheumatoid arthritis (RA) if compatible clinical features of disease are present. A positive result in combination with other signs and symptoms means you have rheumatoid arthritis. Despite its high specificity, previous studies reported that 510% of non-RA connective tissue disease (CTD) patients tested positive for the anti-CCP antibody [1, 2]. Antibodies and autoantibodies are proteins made by the immune system. 2013;33(4):93942. Majka DS, Deane KD, Parrish LA, Lazar AA, Baron AE, Walker CW, et al. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Furthermore, our observation period, 8.9years, was sufficiently long to assess the outcomes of the anti-CCP-positive population because the median period during which an anti-CCP-positive population developed RA was previously reported to be 4.5years [4]. 1988;31(3):31524. SI Abnormal Reports. An antinuclear antibody test is a blood test that looks for certain kinds of antibodies in your body. The false-positive rate of anti-CCP is difficult to come by. Intravenously-administered immunoglobulin therapy is one such treatment that can in theory . Anti CCP antibody assay may be false positive in many patients of tubercular synovitis. A Mayo prospective clinical evaluation of the CCP antibody test showed a diagnostic sensitivity for RA of 78% with fewer than 5% false positive results in healthy controls (see Cautions). Significantly elevated levels of CCP antibodies may be useful to identify RA patients with erosive joint disease. A positive result by itself does not automatically lead to a diagnosis. 3.2.2. Objective: We sought to characterize a novel cohort of patients with lung disease, anti-cyclic citrullinated peptide (CCP) antibody positivity, without rheumatoid arthritis (RA) or other connective tissue disease (CTD). Long-term follow-up of patients with anti-cyclic citrullinated peptide antibody-positive connective tissue disease: a retrospective observational study including information on the HLA-DRB1 allele and citrullination dependency. Prevalence of arthritis in anti-CCP-positive non-RA CTD patients is shown in Supplementary Table1, Additionalfile2. In some cases, patients have even died from complications . There are many infections, connective tissue diseases, malignancies, and advancing age factors associated with false-positive RF tests. Ann Rheum Dis. Provided by the Springer Nature SharedIt content-sharing initiative. What causes false positive anti-CCP antibodies? The Dangers of a Misdiagnosis. 7 Anti-CCP antibodies and anticitrullinated filaggrin antibodies are . TI and SN measured anti-CCP antibody titers by ELISA. All Rights Reserved. CAS Citrullination dependency was more common in patients with SE, although it was not statistically significant (p=0.11) (Fig. About 20% of RA patients are seronegative, meaning that their RF and anti-CCP lab results both continue to come back . Low levels of anti-CCP can be found in the test results of certain patients but may not enough to produce a positive result. 1 Introduction. Specific autoantibodies precede the symptoms of rheumatoid arthritis: a study of serial measurements in blood donors. This test is 97% specific for RA if it is present. Therefore, we retrospectively investigated whether anti-CCP antibody-positive non-RA CTD patients developed RA and clarified whether HLA-DRB1 SE and the citrullination dependency of the anti-CCP antibody are predictive factors for RA. However, the presence of immunoglobulins causing pan-agglutination can cause false-positive results. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements. The sera of patients were collected and stored with written informed consent at various time points in the follow-up period. 2003;48(10):27419. Therefore, the clinical significance of the presence of the anti-CCP antibody in non-RA CTD patients remains unclear. RF positivity, HLA-DRB1 SE possession, and anti-CCP antibody titers may facilitate the differentiation of anti-CCP-positive RA-overlapping CTD from anti-CCP-positive non-RA CTD. The anti-CCP-positive sera of patients may also react with cyclic arginine peptides (CAP), in which the citrulline residues of CCP peptides are substituted with arginine residues. helixhelix in reply to Ngold 7 years ago. However, in 2010, the American College of Rheumatology changed their criteria for diagnosing RA to include the presence of anti-CCP antibodies [9]. Required fields are marked *. To make a conclusive diagnosis, your doctor will take into account both of your antibody results in combination with CRP and ESR tests and any symptoms you have [25]. We screened 842 CTD patients whose primary diagnosis was not RA in our database. Cross M, Smith E, Hoy D, et al: The global burden of rheumatoid arthritis: estimates from the global burden of disease 2010 study. Zhu JN, Nie LY, Lu XY, Wu HX: Meta-analysis: compared with anti-CCP and rheumatoid factor, could anti-MCV be the next biomarker in the rheumatoid arthritis classification criteria? The positive predictive value (PPV) of anti-CCP antibody for erosive arthritis was calculated in each disease subset (n=65, groups 1, 2, and 3 with X-ray images in Fig. Ohmura K, Terao C, Maruya E, Katayama M, Matoba K, Shimada K, et al. CAP, the arginine version of CCP (the citrulline residues of CCP were converted to arginine), and CCP were coated on the same plate, and reactivities against CAP and CCP were compared. Google Scholar. The isotype and IgG subclass distribution of anti-carbamylated protein antibodies in rheumatoid arthritis patients. Celiac disease. 1. (3,4,8,9), Compared to early serologic tests for RA including RF, several studies have demonstrated that ACPA have much improved specificity for RA. Anti-cyclic citrullinated peptide positivity in non-rheumatoid arthritis disease samples: citrulline-dependent or not? Furthermore, the 2010 ACR/EULAR criteria were used to diagnose RA [26]. This includes a combination of medications called disease-modifying antirheumatic drugs (DMARDs) that includes methotrexate (Trexall) and biologics (drugs made from living organisms) such as infliximab (Remicade) and etanercept (Enbrel) [29, 4]. Refining the complex rheumatoid arthritis phenotype based on specificity of the HLA-DRB1 shared epitope for antibodies to citrullinated proteins. 2005;52(12):38138. Arthritis Rheum. Thirty-three anti-CCP-positive non-RA CTD patients were retrospectively followed up for the development of RA. The rheumatoid factor is not clinically significant. Avouac J, Gossec L, Dougados M. Diagnostic and predictive value of anti-cyclic citrullinated protein antibodies in rheumatoid arthritis: a systematic literature review. These antibodies are produced by the person's immune system and identify the body's tissue cells as foreign bodies and attack them. 1), and the mean CTD duration period at anti-CCP testing was 10.19.4years. (3,4,8,9) Compared to early serologic tests for RA including RF, several studies have demonstrated that ACPA have much improved specificity for RA. If not ordering electronically, complete, print, and send a General Request (T239) with the specimen. Development of the anti-citrullinated protein antibody repertoire prior to the onset of rheumatoid arthritis. 2010 Sep;62(9):2569-2581, 3. The closer . ESR and CRP Your email address will not be published. Anti-CCP antibodies may also be detected in other inflammatory diseases and conditions involving the joints and connective tissue, including [4, 5, 6, 7]: Anti-CCP antibodies belong to a family of similar antibodies known as anti-citrullinated protein antibodies (ACPAs) [5]. RFs are used as a marker in individuals with suspected rheumatoid arthritis (RA) or other autoimmune conditions. Due to a higher positive rate than that in the general population (12%) [12, 13], potential differences in autoantigens between RA-overlapping CTD patients and non-RA CTD patients may be a source of concern. All authors approved the final manuscript. which enables users to obtain detailed information and reports based on their genome. Article During the first incubation, serum antibodies bind to adsorbed, solid phase CCP. Koichiro Ohmura. the cause of COVID-19, which has affected more than 6million . 1) and 31 anti-CCP-positive non-RA CTD patients (group 3 in Fig. 1, 7.6%). However, we could not find any significant association of citrullination dependency with erosive disease (OR=4.4 (95% CI 0.3244), p value=0.3). Anti-CCP antibody titers were measured based on the discretion of physicians or when serum or plasma was stored regardless of joint symptoms. Hochberg MC. In the present study, we focused on differences in the citrullination dependency of the anti-CCP antibody. Joe Cohen flipped the script on conventional and alternative medicine and it worked. The false-positive syphilis test was the first recognized test for antiphospholipid antibodies, but it is now known that people can have antiphospholipid antibodies without having . Around 20% of RA patients who test negative for RF will test positive for anti-CCP antibodies [24]. Anti-cardiolipin antibodies are by definition a major criterion for a diagnosis of APS. Sixty-two patients were diagnosed with RA-overlapping CTD before the anti-CCP test was performed. A Mayo Clinic prospective clinical evaluation of the CCP antibody test showed a diagnostic sensitivity for RA of 78% with fewer than 5% false positive results in healthy controls (see Cautions). Irigoyen P, Lee AT, Wener MH, Li W, Kern M, Batliwalla F, et al. The reactivities to CAP and CCP of sera from RA-overlapping CTD patients and non-RA CTD patients were measured by an in-house ELISA and absorbance values at 415nm, and the absorbance values of anti-CAP antibodies were subtracted from those of anti-CCP antibodies for each patient. A plus sign next to the number [1+, 2+, etc] means that the information is found within the full scientific study rather than the abstract. Rantapaa-Dahlqvist S, de Jong BA, Berglin E, Hallmans G, Wadell G, Stenlund H, et al. The possession of HLA-DRB1 SE was also compared between 22 non-RA CTD patients and 32 RA-overlapping CTD patients. False positives are more common with RF than anti-CCP. Arthritis Rheum. Conclusion: There are a number of possible explanations for false-positive HBV serology in a patient with seropositive RA: RhF may non-specifically bind the test antigen reagent used in the assay; RhF (an IgM class anti-human IgG antibody) could bind the mouse mAb IgG used in the assay; and the patient's serum may contain anti-drug antibodies . 2011;70(12):21349. A positive result by itself does not automatically lead to a diagnosis. Beverley. ACPA-positive RA is strongly associated with certain HLA-DRB1 alleles that carry specific amino acid sequences, the so-called shared epitope (SE) [7,8,9,10,11]. False positives are also known to happen in about 5% of tests when a person would be classified as healthy. (3-5) To facilitate early diagnosis, the American College of Rheumatology/European League Against Rheumatism 2010 RA classification criteria recommend testing for rheumatoid factor (RF) and anticitrullinated protein antibodies (ACPA). Arthritis Rheum. The datasets generated and/or analyzed in the present study are available from the corresponding author upon reasonable request. Anti Citrulline. The term false positive may be confusing. Schellekens GA, Visser H, de Jong BA, et al: The diagnostic properties of rheumatoid arthritis antibodies recognizing a cyclic citrullinated peptide. If you also test positive for RF, you likely have the disease [25]. Although all 60 samples tested positive for the anti-CCP antibody using a commercial ELISA kit, 5 out of 33 RA-overlapping CTD and 6 out of 27 non-RA CTD serum samples tested negative using our in-house CCP ELISA. 2017;19(1):190. A negative anti-CCP and negative RF blood test mean you may not have RA, so your healthcare provider may order more tests. CAS Polymyositis and dermatomyositis (first of two parts). The anti-CCP antibodies can exist in a person's system long before they ever exhibit symptoms of RA. SelfDecode is a personalized health report service, SelfDecode has the strictest sourcing guidelines in the health industry and we almost exclusively link to medically peer-reviewed studies, usually on PubMed. (1) Clinically, RA is typified by progressive damage of synovial joints, inflammation, production of diverse autoantibodies, and variable extra-articular manifestations. 2008;58(6):157681. It also have a specificity of around 95%, which is the percentage of results that will be . The frequency of antibodies against cyclic citrullinated peptides and rheumatoid factor in healthy population: a field study of rheumatoid arthritis from northern Turkey. Kakumanu P, Sobel ES, Narain S, Li Y, Akaogi J, Yamasaki Y, et al. A negative result by itself does not rule out the disease. This means that false positives are rare and therefore a positive result means you are much more likely to have RA.