Anticitrullinated protein/peptide antibody assays in early rheumatoid arthritis for predicting five year radiographic damage

OBJECTIVE: To study the value of antibodies to citrullinated proteins/peptides for predicting joint outcomes in patients with recent onset rheumatoid arthritis (RA). METHODS: 191 patients with RA onset within the past year were followed up prospectively for five years. Serum samples obtained from 145 patients at baseline before disease modifying antirheumatic drug treatment were examined using three anticitrullinated protein/peptide antibody assays: antiperinuclear factor (APF) by indirect immunofluorescence (IIF), antikeratin antibodies (AKA) by IIF, and anti-cyclic citrullinated peptide (CCP) antibodies by enzyme linked immunosorbent assay (ELISA). Radiographs of the hands and feet taken at baseline and after three and five years were evaluated using Sharp scores modified by van der Heijde. RESULTS: Anti-CCP ELISA was positive in 58.9% of patients. APF/anti-CCP agreement was 77%. The likelihood of a total Sharp score increase after five years was significantly greater among patients with anti-CCP antibodies (67%; odds ratio (OR) 2.5; 95% confidence interval (95% CI) 1.2 to 5.0) or APF (57%; OR 2.4; 95% CI 1.2 to 4.9) but not rheumatoid factor (RF; OR 0.7; 95% CI 0.3 to 1.5). Mean values for radiographic damage, erosion, and joint narrowing scores at the three times were significantly higher in patients with anti-CCP or APF than in those without. AKA did not significantly predict radiographic damage. In separate analyses of patients with and without RF, anti-CCP or APF was better than RF for predicting total joint damage and joint damage progression after five years. CONCLUSION: Antibodies to citrullinated proteins/peptides determined early in the course of RA by APF IIF or anti-CCP ELISA are good predictors of radiographic joint damage. Further studies of clinical, laboratory, and genetic parameters are needed to improve RA outcome prediction in clinical practice.     

Seronegative rheumatoid arthritis, rheumatoid factor cross reactive idiotype expression, and hidden rheumatoid factors.

The major rheumatoid factor cross reactive idiotype (RCRI), defined by prototypic monoclonal rheumatoid factors (RFs), is expressed as a dominant idiotype by pokeweed mitogen induced plasma cells obtained from seropositive (RF+) patients with rheumatoid arthritis (RA). Some patients who meet clinical diagnostic criteria for RA set by the American Rheumatism Association fail to express RFs at any time during their clinical course. To determine if seronegative (RF-) patients with RA, so designated by the latex fixation, Rose-Waaler classic binding assays, or a RF enzyme linked immunosorbent assay (ELISA), express the RCRI in the absence of detectable RFs we examined pokeweed mitogen plasma cells from these patients by indirect immunofluorescence. In addition, we used an inhibition ELISA to detect RCRI bearing molecules in the sera of RF- patients with RA. Five of 10 RF- patients with RA had a high prevalence of RCRI+ plasma cells (16-49% of total pokeweed mitogen plasma cells in culture). Six of 20 RF- patients with RA had high serum concentrations of molecules marked by the RCRI, equivalent to 21-110 micrograms/ml of RCRI+ reference monoclonal IgM RF. Four of five patients who expressed the RCRI in high prevalence in pokeweed mitogen plasma cells, also demonstrated high concentrations of RCRI in their sera detected by inhibition ELISA. There was significant concordance of RCRI expression determined by the two different assays. Four RF- patients with RA who expressed RCRI in their whole sera had hidden RFs detected in their 19S and, in one case, 7S serum fraction. Detection of RF related molecules in whole sera by the expression of RCRI in RF- patients with RA identifies a subgroup of RF- patients with RA who possess hidden RFs. Some RF- patients with RA can express the major RCRI in pokeweed mitogen plasma cells and in their sera and therefore are related to patients with prototypic Waldenstrom's macroglobulinaemia, who produce RCRI+ 19S IgM monoclonal RFs.     

Independent association of rheumatoid factor and the HLA-DRB1 shared epitope with radiographic outcome in rheumatoid arthritis

OBJECTIVE: Findings of a recent study suggested that HLA-DRB1 alleles encoding the rheumatoid arthritis (RA) "shared epitope" (SE) were not predictive of erosive damage at 2 years in patients with early inflammatory arthritis who were rheumatoid factor (RF) positive, but were predictive in those who were RF negative. The present study was undertaken to determine whether RF status was also important in the association between the SE and radiographic outcome in patients with longstanding RA. METHODS: The association between radiographic outcome, HLA-DRBI, and RF status was examined in 299 RA patients with established disease (5-30 years). Radiographic outcome was measured by scoring radiographs of the hands and feet using the standard radiographs of Larsen. HLA-DRB1 typing was performed using polymerase chain reaction methodology. Results were stratified by RF status and analyzed by multiple regression. RESULTS: An association between radiographic severity and the SE was found in RF-, but not RF+, patients. RF- patients carrying an SE allele had higher Larsen scores than RF- patients lacking the SE, although there was no association with SE dosage. The mean Larsen score was significantly higher in RF+ patients than in RF- patients, but there were no differences between RF+ patients with 0, 1, or 2 SE alleles. Multiple regression analysis confirmed independent associations of RF and SE positivity with radiographic outcome. No significant associations were found between RF and the SE, or RF and individual SE alleles. CONCLUSION: Our data indicate that RF and the SE are independently associated with radiographic outcome in RA. In RF+ patients with longstanding RA, there is no apparent association between the presence of the SE and radiographic damage. However, in RF-patients, although radiographic outcome is generally less severe, there is an association between severity and presence of the SE.     

A comparison of the diagnostic accuracy and prognostic value of the first and second anti-cyclic citrullinated peptides (CCP1 and CCP2) autoantibody tests for rheumatoid arthritis

OBJECTIVES: To compare the diagnostic performance and prognostic value of the anti-cyclic citrullinated peptide (CCP1) and anti-CCP2 autoantibody tests in a clinical setting. METHODS: Anti-CCP1 and anti-CCP2 antibody tests were performed on the same serum samples obtained from 467 patients with early arthritis from the Leiden Arthritis Cohort. The sensitivity, specificity, positive predictive value, and negative predictive value for discriminating between rheumatoid arthritis (RA) and non-RA at 1 year's follow up were calculated for both tests. Results were graphically presented using receiver operating characteristic curves. Progression of radiological joint damage was assessed over 4 years in patients with RA and used to assess the prognostics values of the CCP tests. RESULTS: At a similar specificity the CCP2 test had a higher sensitivity than the CCP1 test. Both tests identified a subgroup of patients with RA with an increased rate of joint damage progression. The anti-CCP2 test identified more patients with an increased rate of joint damage progression than the anti-CCP1 test, and in multiple regression analysis CCP2 was the better predictor of joint damage. CONCLUSIONS: The CCP2 test had better diagnostic and prognostic ability than the CCP1 test.     

Diagnostic and clinical value of anti-cyclic citrullinated peptide antibodies compared with rheumatoid factor isotypes in rheumatoid arthritis

OBJECTIVE: To assess the additional diagnostic and clinical value of the second test generation of anti-cyclic citrullinated peptide antibodies (CCP2) compared with rheumatoid factor isotypes (IgG-RF, IgA-RF, IgM-RF) in patients with rheumatoid arthritis. METHODS: This was a prospective study on 715 patients: rheumatoid arthritis (n = 295), degenerative or other inflammatory joint disease (n = 163), connective tissue disease or vasculitis (n = 103), and healthy controls (n = 154). Sera from each subject were tested for CCP2 and RF isotypes by enzyme linked immunosorbent assay (ELISA). Agreement with clinical indices such as disease activity, joint destruction, disease duration, and other laboratory tests was assessed. Sensitivity and specificity of the tests were evaluated taking the clinical diagnosis as the gold standard. RESULTS: Highest sensitivity was found for IgM-RF (66.4%) and CCP (64.4%). Highest specificity was achieved by CCP (97.1%) and IgG-RF (91.0%). In rheumatoid patients with high disease activity or severe joint damage, CCP was more often present (81.4% and 83.6%) than all RF isotypes. Of special diagnostic value was the detection of positive CCP in 34.5% of all patients with rheumatoid arthritis when all measured RF isotypes (IgG-RF, IgA-RF, and IgM-RF) were negative. CONCLUSIONS: As a screening method for rheumatoid arthritis the IgM-RF and the CCP assays are superior to other RF isotypes. Positivity in the highly specific CCP ELISA supports the diagnosis of rheumatoid arthritis. CCP proved to be a powerful diagnostic tool, especially in ambiguous cases or RF negative patients with rheumatoid arthritis.     

抗核周因子的检测及其在类风湿关节炎中的意义

目的 了解抗核周因子（ＡＰＦ）对类风湿关节炎（ＲＡ）的诊断价值,并探讨其与ＲＡ病情的关系。方法 以健康人颊粘膜细胞为抗原,采用间接免疫荧光法检测１４３例ＲＡ,１８４例其他风湿病患者和１６８例正常人的血清ＡＰＦ;ＲＡ病人的红细胞沉降率（ＥＳＲ）,类风湿因子（ＲＦ）,抗鼠食管角质层抗体（ＡＫＡ）,抗ＲＡ３３抗体,医生和患者病情活动性评价,压痛及肿胀关节指数,放射学病情进展改进的Ｓｈａｒｐ评分也同时评估     

Antiperinuclear factor: indicator of more severe disease in seronegative rheumatoid arthritis

The specificity of antiperinuclear factor (APF) for patients with rheumatoid arthritis (RA) is well documented. It is unknown whether detection of these antibodies adds information to the detection of rheumatoid factor (RF). In a group of 132 patients with RA, 94 were RF positive. Of the 38 patients persistently negative for RF, 14 (37%) were positive for APF. These 14 proved to have a disease course similar to that of RF positive patients. This similarity was shown most impressively by radiological progression of the disease, and to a lesser extent, by the medication needed to control the disease and the number of extraarticular manifestations. No significant correlation was shown between APF and antinuclear antibodies. Among the RF positive patients with their generally poorer prognosis, APF identified the worst affected. Our study suggests that APF in serum of patients with RA is associated with a poor disease outcome, especially in RF negative patients.     

Rheumatoid factor and anticitrullinated protein antibodies in rheumatoid arthritis: diagnostic value, associations with radiological progression rate, and extra-articular manifestations

BACKGROUND: Autoantibodies such as rheumatoid factor (RF) and anticitrullinated protein antibodies can be detected in rheumatoid arthritis (RA) sera. OBJECTIVE: To determine the diagnostic values of RF, anticitrullinated protein antibodies, and the shared epitope (SE), and their associations with radiological progression rates and extra-articular manifestations. METHODS: Population 1 consisted of sera from 315 patients, consecutively sent for detection of anticitrullinated protein antibodies, of which 264 were used to determine the sensitivity and specificity of RF and of antibodies against three synthetic citrullinated peptides: peptide A (pepA), peptide B (pepB), and CCP2. Population 2 consisted of sera from 180 longstanding RA patients and was used to determine associations of RA associated antibodies and the SE with radiological progression rates and extra-articular manifestations. Antibodies to pepA and pepB were detected by line immunoassay, and antibodies to CCP2 by ELISA. HLA Class II typing was performed by LiPA. RESULTS: In population 1, we defined adapted cut offs corresponding to a specificity of >/=98.5%. This yielded the following sensitivities: RF 12.8%; anti-pepA antibodies 63.6%; anti-pepB antibodies 54.2%; and anti-CCP2 antibodies 73.7%. In population 2, significant differences in radiological progression rates were found between positive and negative patients for different RA antibodies and the SE. RF, but not anticitrullinated protein antibodies or the SE, were more frequent in patients with extra-articular manifestations. CONCLUSION: A valid comparison of RA associated antibodies shows superior sensitivity of the anticitrullinated protein antibodies compared with RF. The presence of RA associated antibodies and the SE are indicative for poorer radiological outcome, and presence of extra-articular manifestations is associated with RF but not with anticitrullinated protein antibodies.     

Prevalence and clinical significance of antikeratin antibodies and other serological markers in Lithuanian patients with rheumatoid arthritis

OBJECTIVES: To assess the clinical value of several serological markers in Lithuanian patients with rheumatoid arthritis (RA) compared with control patients with rheumatic disease and age matched healthy controls. METHODS: Serum samples from 96 patients with RA of approximately 8 years' duration, 90 rheumatic disease controls, and 37 healthy subjects were tested. Antikeratin antibody (AKA), antineutrophil cytoplasmic antibody (ANCA), and antinuclear antibody (ANA) titres were estimated by indirect immunofluorescence (IIF) and serum samples positive for ANA and ANCA were further studied by enzyme linked immunosorbent assay (ELISA). IgA and IgM rheumatoid factors (RF) were measured by ELISA. RESULTS: A positive AKA test was highly specific for RA (diagnostic specificity 97%), being found in 44% of the patients. Although both RF tests had a higher sensitivity, they were less specific for RA. ANCA was detected in 33% of patients with RA but lacked diagnostic specificity. AKA and ANCA were associated with more erosive disease and the presence of extra-articular manifestations. Positivity for AKA, IgA RF, and ANCA was significantly associated with disease activity and worse functional capacity. However, in multiple regression analysis only positivity for AKA was significantly correlated with functional disability (p=0.0001), evaluated by the Steinbrocker functional classification, and no single marker had any relation with radiological damage. CONCLUSION: Although AKA showed the highest disease specificity, all serological markers studied except ANA exhibited interesting associations with important clinical and paraclinical parameters of RA.     

The prevalence of rheumatoid factor isotypes and anti-cyclic citrullinated peptides in Malaysian rheumatoid arthritis patients

Aim: The purpose of this study is to compare the prevalence of rheumatoid factor (RF) isotypes and second generation anti‐cyclic citrullinated peptides (anti‐CCP) in Malaysian rheumatoid arthritis (RA) patients. Methods: In this cross‐sectional study, 147 established RA patients from three ethnic groups were recruited from a major rheumatology clinic in Malaysia. Enzyme‐linked immunosorbent assays (ELISA) for serum RF isotypes IgA, IgG and IgM as well as second‐generation anti‐CCP were performed and the prevalence of each auto‐antibody was compared in the three ethnic groups. Results: The anti‐CCP was the most prevalent auto‐antibody in each of the ethnic groups, followed closely by RF IgM and RF IgG. Rheumatoid factor IgA was the least prevalent across all three ethnic groups. The anti‐CCP–RF IgM combination provided the best test sensitivity. Seroprevalence of anti‐CCP was strongly associated with the presence of each of the RF isotypes. The seroprevalence of RF and anti‐CCP did not increase or decrease with advancing age, age at onset and disease duration. Conclusion: When used alone, anti‐CCP provides a diagnostic advantage over RF IgM on the basis of test sensitivity. Considering the high cost of the anti‐CCP assay, step‐wise serum testing with IgM RF followed by anti‐CCP may provide a more economically sensible option to optimize test sensitivity for RA.     

The effects of tobacco smoking and rheumatoid factor seropositivity on disease activity and joint damage in early rheumatoid arthritis

OBJECTIVE: To study the effect of tobacco smoking and rheumatoid factor (RF) isotypes on disease activity and joint damage in early rheumatoid arthritis (RA). METHODS: One hundred early RA patients were followed prospectively for 2 yr. They were evaluated at recruitment and at 6 and 24 months. Sociodemographic information included smoking history, and radiographs of hands and feet were obtained. RF was monitored by IgM- and IgA-specific RF enzyme-linked immunosorbent assay and by agglutination, and serial measurements were also obtained for C-reactive protein. The influence of tobacco smoking and RF positivity on disease outcome was evaluated using multivariate analysis. Covariates for the regression analysis included sex, age, coffee consumption and IgA-RF positivity. RESULTS: A gradient of increase in disease activity was observed from never smokers to former smokers to current smokers during the 2 yr of observation, defined by number of swollen joints (SJC), tender joints (TJC) and visual analogue scale for pain (P<0.001, P=0.02 and P=0.005, respectively), but smoking status did not influence radiological progression. Ever smokers were more often IgA RF positive (P<0.05). IgA RF-positive patients had more active disease (SJC P=0.002, TJC P=0.01) and showed more radiological progression (P<0.0001) compared with IgA RF-negative patients. Of the RF-positive patients 22% had elevated IgM RF without IgA RF and these patients showed similar disease activity and radiological joint progression to the RF-negative patients. None of these associations were explained by possible confounders. CONCLUSION: Tobacco smoking has an adverse effect on patients with early RA and this is possibly immunologically mediated. IgM RF does not predict poorer prognosis in RA unless it is associated with a concomitant elevation of IgA RF.     

Diagnostic value of anti-cyclic citrullinated Peptide antibody in patients with rheumatoid arthritis

OBJECTIVE: To explore the diagnostic value of anti-cyclic citrullinated peptide antibody (anti-CCP) detected by ELISA in patients with rheumatoid arthritis (RA). METHODS: The synthesized cyclic citrullinated peptide was used as substrate for ELISA. Anti-CCP antibody was detected by ELISA in 191 patients with RA, 132 with rheumatic diseases other than RA, and 98 with nonrheumatic diseases. The antiperinuclear factor (APF), anti-keratin antibody (AKA), rheumatoid factor (RF), and HLA-DR4 gene complex were also tested in each RA patient. The results of these tests were compared with anti-CCP antibody to examine the correlation between them. RESULTS: Ninety (47.1%) patients with RA, 4 (3.0%) with other rheumatic diseases, and 2 (2.0%) with nonrheumatic diseases were found to be anti-CCP antibody positive by ELISA. The sensitivity of anti-CCP antibody was 47.1%, with a high specificity (97.4%) in RA. Anti-CCP antibody correlated with APF, AKA, RF, and HLA-DR4 gene complex. CONCLUSION: A new modified anti-CCP antibody test had a moderate sensitivity (47.1%) but a high specificity (97.4%) in patients with RA and was found as a valuable supplement to diagnosis of RA. Anti-CCP correlated with APF, AKA, RF, and HLA-DR4 gene complex, but did not completely overlap with them. Anti-CCP antibody could be regarded as a new diagnostic marker for RA.     

Smoking, rheumatoid factor isotypes and severity of rheumatoid arthritis

OBJECTIVES: Smokers have an increased incidence of rheumatoid factor (RF) and rheumatoid arthritis (RA) and one report has also indicated that smoking may also adversely influence the severity of RA. METHODS: Sixty-three women with advanced RA answered a structured questionnaire that included detailed information about their smoking history. The women were also evaluated clinically and radiologically. RESULTS: Heavy smoking (>/= 20 pack-yr) was associated with rheumatoid nodules (P: = 0.01), a higher HAQ score (P: = 0.002) and a lower grip strength (P: = 0.01). Smoking was also associated with more radiological joint damage (P: = 0.02). A positive correlation was observed between smoking and RF levels, in particular IgA RF and a combined elevation of IgM and IgA RF. CONCLUSIONS: Smoking has an adverse effect on disease progression in patients with RA. An association was also observed between smoking and those RF types that predispose to RA and have the highest diagnostic specificity for this disease.     

Antiperinuclear factor as a prognostic marker in rheumatoid arthritis

OBJECTIVE: Antiperinuclear factor (APF) is an autoantibody detected in >50% of patients with rheumatoid arthritis (RA); it shows a specificity of roughly 90%. We investigated the possible role of APF as a prognostic marker in RA. METHODS: A series of 103 patients with RA who fulfilled the 1987 American College of Rheumatology criteria (88 women and 15 men; mean age 55.5 yrs, mean disease duration 9 yrs) were prospectively followed. Sixteen variables were assessed in each patient at inclusion and over a 3 year period. APF was determined by indirect immunofluorescence assay using human buccal mucosal cells as substrate. APF assays were done at entry and at the end of followup without knowledge of the clinical status of the patients. Mann-Whitney U, chi-squared tests, variance analysis, and kappa index were used for statistical analysis. RESULTS: Eighty of 103 patients completed followup. APF was detected in 40 of 80. At inclusion, APF correlated with the visual analog scale (VAS) of pain (p = 0.02). However, patients who showed APF positivity at entry had a less favorable course than APF negative individuals, as shown by a worse VAS of well being (p = 0.01), Ritchie index (p = 0.01), number of painful joints (p = 0.03), grip strength (p = 0.01), C-reactive protein (p = 0.04), and Health Assessment Questionnaire score (p = 0.03) at the end of the study. In addition, APF positive patients showed a worse radiological course (p = 0.03). CONCLUSION: Our results suggest APF is a possible marker of poor prognosis in RA.     

抗环瓜氨酸肽抗体检测在类风湿关节炎中的意义

目的 检测抗环瓜氨酸肽（CCP）抗体在类风湿关节炎（RA）中的阳性率,探讨抗CCP抗体检测在RA中的意义。方法 以根据已知cDNA序列人工合成的CCP为抗原建立ELISA方法检测294例RA,132例其他风湿性疾病,135例非风湿性疾病中的抗CCP抗体的分布。比较抗CCP抗体与抗核周因子（APF）、抗角蛋白抗体（AKA）、类风湿因子（RF）以及HLA－DR4的相关性。结果 294例RA病人中,抗CCP抗体的阳性率为46．6％,其他风湿性疾病的阳性率为5．3％,非风湿性疾病的阳性率为1．5％。抗CCP抗体对RA的敏感性和特异性分别为46．6％,96．6％。抗CCP抗体与APF、AKA以及HLA－DR4之间有相关性,与RF之间无相关性。结论 抗CCP抗体对RA具有良好的敏感性（46．6％）和特异性（96．6％）,能用于RA的诊断。抗CCP抗体与AFP、AKA有相关性,但不完全重叠。抗CCP抗体可视为RA新的血清学诊断指标。     

Mortality trends in rheumatoid arthritis: the role of rheumatoid factor

OBJECTIVE: We previously demonstrated a widening in the mortality gap between subjects with rheumatoid arthritis (RA) and the general population. We examined the contribution of rheumatoid factor (RF) positivity on overall mortality trends and cause-specific mortality. METHODS: A population-based RA incidence cohort (1955-1995, and aged >or= 18 yrs) was followed longitudinally until death or January 1, 2006. The underlying cause of death as coded from national mortality statistics and grouped according to ICD-9/10 chapters was used to define cause-specific mortality. Expected cause-specific mortality rates were estimated by applying the age-, sex-, and calendar-year-specific mortality rates from the general population to the RA cohort. Poisson regression was used to model the observed overall and cause-specific mortality rates according to RF status, accounting for age, sex, disease duration, and calendar year. RESULTS: A cohort of 603 subjects (73% female; mean age 58 yrs) with RA was followed for a mean of 16 years, during which 398 died. Estimated survival at 30 years after RA incidence was 26.0% in RF+ RA subjects compared to 36.0% expected (p < 0.001), while in RF- RA subjects, estimated survival was 29.1% compared to 28.3% expected (p = 0.9). The difference between the observed and the expected mortality in the RF+ RA subjects increased over time, resulting in a widening of the mortality gap, while among RF- RA subjects, observed mortality was very similar to the expected mortality over the entire time period. Among RF+ RA subjects, cause-specific mortality was higher than expected for cardiovascular [relative risk (RR) 1.50; 95% confidence interval (CI) 1.22, 1.83] and respiratory diseases [RR 3.49; 95% CI 2.51, 4.72]. Among RF- RA subjects, no significant differences were found between observed and expected cause-specific mortality. CONCLUSION: The widening in the mortality gap between RA subjects and the general population is confined to RF+ RA subjects and largely driven by cardiovascular and respiratory deaths.     

Anti-microtubule organizing center with microtubule by autoimmune target test is also useful serological marker in rheumatoid arthritis evaluation

Seropositivity of rheumatoid factor (RF) or anti-cyclic citrullinated peptide antibody (anti-CCP) is one domain of scoring system in new American College of Rheumatology/European League against Rheumatism classification criteria for rheumatoid arthritis (RA). We investigated usefulness of antiperinuclear factor (APF) and autoantibody to microtubule organizing center with microtubule (anti-MTOC-MT), which was detected by autoimmune target (AIT) test, as serological markers for the diagnosis of early RA. The test results of 3,503 patients from the outpatient clinic of The Hospital for Rheumatic Diseases who underwent test for RF, APF, anti-CCP and anti-MTOC-MT simultaneously for the work-up of RA were analyzed. Four kinds of tests showed same results only in 53.1% (1,861/3,503) of all subjects. The kappa coefficient between each test was distributed from ?0.011 to 0.622. The agreement was best between RF and anti-CCP (kappa coefficient: 0.622), but the agreement was poor between anti-MTOC-MT and other 3 tests (kappa coefficient: 0.007 to ?0.025). In both of RF- and anti-CCP-negative patients, the patients who showed positive result for APF were 4.6% (160/3,503) and for anti-MTOC-MT were 13.2% (464/3,503). RF and anti-CCP positivity could not include all of APF and anti-MTOC-MT positivity. Anti-MTOC-MT detected by AIT test was independent serological marker, and it might be also helpful for the diagnosis of early RA. Therefore, the combined detection of all four serologic markers can be useful for the evaluation of suspected RA patients.     

The diagnostic significance of the antiperinuclear factor for rheumatoid arthritis

Sensitivity and specificity of antiperinuclear factor (APF) determination were assessed in 127 patients with classical or definite rheumatoid arthritis (RA). The control population consisted of 262 patients with rheumatic complaints other than RA. Our results showed a sensitivity of 86.6%, a specificity of 96.2% and a Youden index of 82.8% for APF in RA. In 14.2% of the total population with RA the rheumatoid factor (RF) became negative in the course of the disease; all but one were found to be actually APF positive. Of the population with RA analyzed, 8.6% were consistently RF negative but APF positive. In view of its strong sensitivity and specificity for RA, APF determination is a valuable serological tool for the diagnosis of the disease. In APF positive, RF negative patients with RA the prognosis seems to be poor.     

An eight year prospective study of outcome prediction by antiperinuclear factor and antikeratin antibodies at onset of rheumatoid arthritis

OBJECTIVES: Antikeratin antibodies (AKA) and antiperinuclear factor (APF) are specific antibodies found very early in rheumatoid arthritis (RA). The objective of this eight year follow up study was to assess the value of early AKA and APF assays in predicting functional disability and cartilage damage. METHOD: In 2000, 64 patients tested for AKA and APF (antifilaggrin antibodies) between 1990 and 1993 during evaluation of early symmetric oligoarthritis or polyarthritis (suspected RA) were invited to participate in this non-concurrent cohort study. The Health Assessment Questionnaire (HAQ) score, disease activity score (DAS), and Larsen radiographic score were the primary evaluation criteria. RESULTS: Twenty nine patients were re-evaluated. Clinical and laboratory data obtained in 1993 were similar in this group and in the 35 other patients. Twenty five patients had received a diagnosis of RA. Nine (31%) were rheumatoid factor (RF) positive, nine (31%) were AKA positive, and six (21%) were APF positive during the first year of the disease. APF was correlated with the Larsen score (p=0.011) and DAS (p=0.035) evaluated after a mean disease duration of 8.55 years. All APF positive patients had erosive disease. AKA was correlated with the DAS (p=0.035). CONCLUSION: The presence of AKA or APF early in the course of RA was associated with the DAS or Larsen score eight years later. The number of patients was small, but the findings confirmed those of studies with shorter follow ups. Antifilaggrin antibodies should be included in the initial investigation of patients with RA and, when positive, should alert to a high risk of poor outcomes.     

Rheumatoid factor is the strongest predictor of radiological progression of rheumatoid arthritis in a three-year prospective study in community-recruited patients

OBJECTIVE: To evaluate the predictive value of clinical, biological and radiological parameters for the prognosis of rheumatoid arthritis (RA) in a community-recruited cohort. METHODS: Ninety-one patients (mean age 49 yr, female/male ratio 2.9) with RA of limited duration (median 2 yr), 80% recruited from the community, were prospectively enrolled in 1996 (T1) and followed until 1999 (T2). Data collected at T1 were demographic characteristics, Ritchie articular index (RAI), extra-articular manifestations, Health Assessment Questionnaire (HAQ) score, C-reactive protein (CRP) and autoantibodies (autoAbs) [rheumatoid factors (RF), detected by latex fixation test and ELISA (IgM, IgA and IgG isotypes), anti-filaggrin, detected by immunofluorescence (anti-keratin antibodies, AKA; anti-perinuclear factor antibodies, APF) and ELISA (anti-citrullinated rat filaggrin antibodies, ACRFA), anti-Sa, anti-calpastatin recognizing the 27 C-terminal fragment (ACAST-C27) and domain I (ACAST-DI), anti-cardiolipin (ACL), antineutrophil cytoplasmic antibodies (ANCA), anti-annexin V (aANX V) and anti-Ro]. Hands were radiographed at T1 and T2, and read using the Sharp method as modified by van der Heijde. The main assessment criterion was progression of radiologically detected damage between T1 and T2. RESULTS: At T1, RA activity was mild (RAI 11/78; mean CRP 14 mg/ml), with minor functional disability (HAQ 0.8/3) and mild X-ray destruction (mean total Sharp score 9.2/280). At T1, 96% of the patients were on treatment (prednisone 72%, DMARDs 95%). The latex test detected autoAb in 46% of patients, RF-IgM was detected in 51%, RF-IgA in 36%, RF-IgG in 32%, AKA in 33%, APF in 45%, ACRFA in 45%, ACAST-C27 in 14%, ACAST-DI in 5%, anti-Sa in 22%, ACL in 3%, ANCA in 28%, aANX V in 9% and anti-Ro in 2%. At T2, the mean total Sharp score was 22.9. According to univariate analysis, T1 parameters associated with the independent variable were RAI, HAQ, CRP, latex test positivity and T1 Sharp scores. Multivariate analysis retained only latex test positivity and, to a lesser degree, joint-space narrowing score as independent predictors of radiological progression. CONCLUSION: RF is the main factor that can predict radiological progression in community cases of RA of limited duration.