Identification of connective tissue disease autoantibodies and a novel autoantibody anti-annexin A11 in patients with "idiopathic" interstitial lung disease.

BACKGROUND: Autoantibodies are a hallmark feature of Connective Tissue Diseases (CTD). Their presence in patients with idiopathic interstitial lung disease (ILD) may suggest covert CTD. We aimed to determine the prevalence of CTD autoantibodies in patients diagnosed with idiopathic ILD. METHODS: 499 patient sera were analysed: 251 idiopathic pulmonary fibrosis (IPF), 206 idiopathic non-specific interstitial pneumonia (iNSIP) and 42 cryptogenic organising pneumonia (COP). Autoantibody status was determined by immunoprecipitation. RESULTS: 2.4% of IPF sera had a CTD-autoantibody compared to 10.2% of iNSIP and 7.3% of COP. 45% of autoantibodies were anti-synthetases. A novel autoantibody targeting an unknown 56 kDa protein was found in seven IPF patients (2.8%) and two NSIP (1%) patients. This was characterised as anti-annexin A11. CONCLUSION: Specific guidance on autoantibody testing and interpretation in patients with ILD could improve diagnostic accuracy. Further work is required to determine the clinical significance of anti-annexin A11.

Epidemiology of systemic sclerosis in the UK: an analysis of the Clinical Practice Research Datalink.

OBJECTIVES: We developed and tested a robust case ascertainment strategy within the Clinical Practice Research Datalink (CPRD), with the aim of assessing the incidence, prevalence, mortality and delay in diagnosis of SSc in the UK. METHODS: A two-stage case ascertainment strategy was devised and tested to establish a valid cohort of SSc cases within the CPRD. Incidence, prevalence and mortality statistics were analysed, alongside evaluation of the relationship between primary care codes for RP and SSc to examine diagnostic delay. RESULTS: SSc Read codes were identified in 3123 patients (from a study cohort of >10.1 million individuals). Of these, 1757 cases of SSc were identified using our case ascertainment approach. The overall incidence rate of SSc over the period between 1999 and 2017 was 10.7/million/year (95% CI: 9.9-11.4), being higher in females [17.69/million/year (95% CI: 16.32-19.07)] than in males [3.59/million/year (95% CI: 2.97-4.21)]. The overall prevalence of SSc in adults was 235.5/million (95% CI: 207.2-245.7). The mean rate of mortality was 32/1000 person-years, with an overall standardized mortality ratio of 3.51 (95% CI: 3.19-3.84). Of those with an initial code of RP prior to a Read code of SSc, 191/854 (22.4%) had a lag period of >10 years. CONCLUSION: We have developed and tested a robust case ascertainment strategy to examine the incidence, prevalence, mortality and diagnostic delay of SSc using primary care records of over 10 million UK residents. A significant lag between coding of RP and SSc in many patients suggests diagnostic delay in SSc remains an important unmet need.

Identification and prediction of novel classes of long-term disease trajectories for patients with juvenile dermatomyositis using growth mixture models.

OBJECTIVES: Uncertainty around clinical heterogeneity and outcomes for patients with JDM represents a major burden of disease and a challenge for clinical management. We sought to identify novel classes of patients having similar temporal patterns in disease activity and relate them to baseline clinical features. METHODS: Data were obtained for n = 519 patients, including baseline demographic and clinical features, baseline and follow-up records of physician's global assessment of disease (PGA), and skin disease activity (modified DAS). Growth mixture models (GMMs) were fitted to identify classes of patients with similar trajectories of these variables. Baseline predictors of class membership were identified using Lasso regression. RESULTS: GMM analysis of PGA identified two classes of patients. Patients in class 1 (89%) tended to improve, while patients in class 2 (11%) had more persistent disease. Lasso regression identified abnormal respiration, lipodystrophy and time since diagnosis as baseline predictors of class 2 membership, with estimated odds ratios, controlling for the other two variables, of 1.91 for presence of abnormal respiration, 1.92 for lipodystrophy and 1.32 for time since diagnosis. GMM analysis of modified DAS identified three classes of patients. Patients in classes 1 (16%) and 2 (12%) had higher levels of modified DAS at diagnosis that improved or remained high, respectively. Patients in class 3 (72%) began with lower DAS levels that improved more quickly. Higher proportions of patients in PGA class 2 were in DAS class 2 (19%, compared with 16 and 10%). CONCLUSION: GMM analysis identified novel JDM phenotypes based on longitudinal PGA and modified DAS.

A systematic review and meta-analysis to inform cancer screening guidelines in idiopathic inflammatory myopathies.

OBJECTIVES: To identify clinical factors associated with cancer risk in the idiopathic inflammatory myopathies (IIMs) and to systematically review the existing evidence related to cancer screening. METHODS: A systematic literature search was carried out on Medline, Embase and Scopus. Cancer risk within the IIM population (i.e. not compared with the general population) was expressed as risk ratios (RR) for binary variables and weighted mean differences (WMD) for continuous variables. Evidence relating to cancer screening practices in the IIMs were synthesized via narrative review. RESULTS: Sixty-nine studies were included in the meta-analysis. DM subtype (RR 2.21), older age (WMD 11.19), male sex (RR 1.53), dysphagia (RR 2.09), cutaneous ulceration (RR 2.73) and anti-transcriptional intermediary factor-1 gamma positivity (RR 4.66) were identified as being associated with significantly increased risk of cancer. PM (RR 0.49) and clinically amyopathic DM (RR 0.44) subtypes, Raynaud's phenomenon (RR 0.61), interstitial lung disease (RR 0.49), very high serum creatine kinase (WMD -1189.96) or lactate dehydrogenase (WMD -336.52) levels, and anti-Jo1 (RR 0.45) or anti-EJ (RR 0.17) positivity were identified as being associated with significantly reduced risk of cancer. Nine studies relating to IIM-specific cancer screening were included. CT scanning of the thorax, abdomen and pelvis appeared to be effective in identifying underlying asymptomatic cancers. CONCLUSION: Cancer risk factors should be evaluated in patients with IIM for risk stratification. Screening evidence is limited but CT scanning could be useful. Prospective studies and consensus guidelines are needed to establish cancer screening strategies in IIM patients.

Composite Measures for Clinical Trials in Psoriatic Arthritis: Testing Pain and Fatigue Modifications in a UK Multicenter Study.

OBJECTIVE: To test the addition of pain and fatigue to the Composite Psoriatic Arthritis Disease Activity (CPDAI) and the Group for Research and Assessment of Psoriasis and PsA (GRAPPA) Composite Exercise (GRACE) composite measures of psoriatic arthritis (PsA). METHODS: Clinical and patient-reported outcome measures were assessed in patients with PsA at 3 consecutive follow-up visits over 6 months in a UK multicenter observational study. A pain visual analog scale and Functional Assessment of Chronic Illness Therapy Fatigue scale were added as modifications to the CPDAI and GRACE composite measures. Original and modified versions were tested against the PsA Disease Activity Score (PASDAS) and the Disease Activity Index for PsA (DAPSA). Discrimination between disease states and responsiveness were tested with t-scores, standardized response means (SRMs), and effect sizes. Data were presented to members at the 2020 annual meeting who then voted on the GRAPPA-recommended composite and treatment targets for clinical trials. RESULTS: One hundred forty-one patients were recruited with a mean PsA disease duration of 6.1 years (range 0-41 yrs). The SRMs for the GRACE and modified GRACE (mGRACE) were 0.67 and 0.64, respectively, and 0.54 and 0.46, respectively, for the CPDAI and modified CPDAI (mCPDAI). The t-scores for the GRACE and mGRACE were unchanged at 7.8 for both, and 6.8 and 7.0 for the CPDAI and mCPDAI, respectively. The PASDAS demonstrated the best responsiveness (SRM 0.84) and discrimination (t-scores 8.3). Most members (82%) agreed the composites should not be modified and 77% voted for the PASDAS as the GRAPPA-recommended composite for clinical trials, with 90% minimal disease activity (MDA) as the target. CONCLUSION: Modifying the CPDAI and GRACE with the addition of pain and fatigue does not enhance responsiveness nor the measures' ability to detect disease status in terms of requiring treatment escalation. GRAPPA members voted for the PASDAS as the composite measure in clinical trials and MDA as the target.

Composite Measures for Routine Clinical Practice in Psoriatic Arthritis: Testing of Shortened Versions in a UK Multicenter Study.

OBJECTIVE: To test shortened versions of the psoriatic arthritis (PsA) composite measures for use in routine clinical practice. METHODS: Clinical and patient-reported outcome measures (PROMs) were assessed in patients with PsA at 3 consecutive follow-up visits in a UK multicenter observational study. Shortened versions of the Composite Psoriatic Arthritis Disease Activity Index (CPDAI) and Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) Composite Exercise (GRACE) measures were developed using PROMs and tested against the Disease Activity Score in 28 joints (DAS28), composite Disease Activity in Psoriatic Arthritis, and Routine Assessment of Patient Index Data (RAPID3). Discrimination between disease states and responsiveness were tested with the t-score, standardized response mean (SRM), and effect size (ES). Data were presented to members at the GRAPPA 2020 annual meeting and members voted on the recommended composite routine practice. RESULTS: The SRM for the GRACE, 3 visual analog scale (VAS), and 4VAS were 0.67, 0.77, and 0.63, respectively, and for CPDAI and shortened CPDAI (sCPDAI) were 0.54 and 0.55, respectively. Shortened versions of the GRACE increased the t-score from 7.8 to 8.7 (3VAS) and 9.0 (4VAS), but reduced the t-score in the CPDAI/sCPDAI from 6.8 and 6.1. The 3VAS and 4VAS had superior performance characteristics to the sCPDAI, DAS28, Disease Activity in Psoriatic Arthritis, and RAPID3 in all tests. Of the members, 60% agreed that the VAS scales contained enough information to assess disease and response to treatment, 53% recommended the 4VAS for use in routine care, and 26% the 3VAS, while leaving 21% undecided. Conclusion. Shortening the GRACE to VAS scores alone enhances the ability to detect status and responsiveness and has the best performance characteristics of the tested composite measures. GRAPPA members recommend further testing of the 3VAS and 4VAS in observational and trial datasets.

The reliability of immunoassays to detect autoantibodies in patients with myositis is dependent on autoantibody specificity.

OBJECTIVES: In order to address the reliability of commercial assays to identify myositis-specific and -associated autoantibodies, we aimed to compare the results of two commercial immunoassays with the results obtained by protein immunoprecipitation. METHODS: Autoantibody status was determined using radio-labelled protein immunoprecipitation for patients referred to our laboratory for myositis autoantibody characterization. For each autoantibody of interest, the sera from 25 different patients were analysed by line blot (Euroline Myositis Antigen Profile 4, EuroImmun, Lübeck, Germany) and dot blot (D-Tek BlueDiver, Diagnostic Technology, Belrose, NSW, Australia). Sera from 134 adult healthy controls were analysed. RESULTS: Overall commercial assays performed reasonably well, with high agreement (Cohen's κ >0.8). Notable exceptions were the detection of rarer anti-synthetases with κ < 0.2 and detection of anti-TIF1γ, where κ was 0.70 for the line blot and 0.31 for dot blot. Further analysis suggested that the proportion of patients with anti-TIF1γ may recognize a conformational epitope, limiting the ability of blotting-based assays that utilize denatured antigen to detect this clinically important autoantibody. A false-positive result occurred in 13.7% of samples analysed by line blot and 12.1% analysed by dot blot. CONCLUSION: The assays analysed do not perform well for all myositis-specific and -associated autoantibodies and overall false positives are relatively common. It is crucial that clinicians are aware of the limitations of the methods used by their local laboratory. Results must be interpreted within the clinical context and immunoprecipitation should still be considered in selected cases, such as apparently autoantibody-negative patients where anti-synthetase syndrome is suspected.

The myositis clinical phenotype associated with anti-Zo autoantibodies: a case series of nine UK patients.

OBJECTIVES: It has been over 10 years since the first report of autoantibodies directed against phenylalanyl tRNA synthetase (anti-Zo) in a patient with features of the anti-synthetase syndrome. In that time no further cases have been published. Here we aim to characterize more fully the clinical phenotype of anti-Zo-associated myositis by describing the clinical features of nine patients. METHODS: Anti-Zo was identified by protein-immunoprecipitation in patients referred for extended spectrum myositis autoantibody testing at our laboratory. Results were confirmed by immunodepletion using a reference serum. Medical records were retrospectively reviewed to provide detailed information of the associated clinical phenotype for all identified patients. Where possible, HLA genotype was imputed using Illumina protocols. RESULTS: Nine patients with anti-Zo were identified. The median age at disease onset was 51 years, and six patients were female. Seven patients had evidence of inflammatory muscle disease, seven of interstitial lung disease and six of arthritis. The reported pattern of interstitial lung disease varied with usual interstitial pneumonia, non-specific interstitial pneumonia and organizing pneumonia all described. Other features of the anti-synthetase syndrome such as RP and mechanics hands were common. HLA data was available for three patients, all of whom had at least one copy of the HLA 8.1 ancestral haplotype. CONCLUSION: Patients with anti-Zo presenting with features of the anti-synthetase syndrome and interstitial lung disease is a common finding. Like other myositis autoantibodies, there is likely to be a genetic association with the HLA 8.1 ancestral haplotype.

Focused HLA analysis in Caucasians with myositis identifies significant associations with autoantibody subgroups.

OBJECTIVES: Idiopathic inflammatory myopathies (IIM) are a spectrum of rare autoimmune diseases characterised clinically by muscle weakness and heterogeneous systemic organ involvement. The strongest genetic risk is within the major histocompatibility complex (MHC). Since autoantibody presence defines specific clinical subgroups of IIM, we aimed to correlate serotype and genotype, to identify novel risk variants in the MHC region that co-occur with IIM autoantibodies. METHODS: We collected available autoantibody data in our cohort of 2582 Caucasian patients with IIM. High resolution human leucocyte antigen (HLA) alleles and corresponding amino acid sequences were imputed using SNP2HLA from existing genotyping data and tested for association with 12 autoantibody subgroups. RESULTS: We report associations with eight autoantibodies reaching our study-wide significance level of p<2.9×10-5. Associations with the 8.1 ancestral haplotype were found with anti-Jo-1 (HLA-B*08:01, p=2.28×10-53 and HLA-DRB1*03:01, p=3.25×10-9), anti-PM/Scl (HLA-DQB1*02:01, p=1.47×10-26) and anti-cN1A autoantibodies (HLA-DRB1*03:01, p=1.40×10-11). Associations independent of this haplotype were found with anti-Mi-2 (HLA-DRB1*07:01, p=4.92×10-13) and anti-HMGCR autoantibodies (HLA-DRB1*11, p=5.09×10-6). Amino acid positions may be more strongly associated than classical HLA associations; for example with anti-Jo-1 autoantibodies and position 74 of HLA-DRB1 (p=3.47×10-64) and position 9 of HLA-B (p=7.03×10-11). We report novel genetic associations with HLA-DQB1 anti-TIF1 autoantibodies and identify haplotypes that may differ between adult-onset and juvenile-onset patients with these autoantibodies. CONCLUSIONS: These findings provide new insights regarding the functional consequences of genetic polymorphisms within the MHC. As autoantibodies in IIM correlate with specific clinical features of disease, understanding genetic risk underlying development of autoantibody profiles has implications for future research.

The performance of the European League Against Rheumatism/American College of Rheumatology idiopathic inflammatory myopathies classification criteria in an expert-defined 10 year incident cohort.

OBJECTIVES: To assess the performance of the EULAR/ACR idiopathic inflammatory myopathies (IIMs) classification criteria in a cohort of incident IIM cases and examine how criteria-assigned IIM subtype correlates with expert opinion. METHODS: Adults with newly diagnosed IIM attending Salford Royal NHS Foundation Trust were identified over a 10 year period. A retrospective review of all putative cases was performed and those fulfilling a consensus expert opinion diagnosis of IIM were included. Clinical, serological and histological data were collected and each case was assigned a single IIM subtype. The EULAR/ACR classification criteria were then applied and sensitivity, specificity and positive and negative predictive values were calculated, presented with 95% CIs. RESULTS: A total of 1637 cases were screened, with 255 consensus expert opinion IIM cases ultimately identified. Applying the EULAR/ACR classification criteria, the sensitivity to diagnose an IIM was 99.6% (95% CI 97.2, 100) and 80.9% (95% CI 76.0, 85.8) for the criteria cut-points of probable and definite diagnoses, respectively. In 94/255 cases the IIM subtype differed between consensus expert opinion and classification criteria, most strikingly in the group subtyped as PM by the EULAR/ACR criteria, where there was discrepancy in the majority (i.e. in 87/161). CONCLUSION: The EULAR/ACR criteria performed with high sensitivity in identifying IIM in this external cohort of incident IIM. However, substantial disagreements arose between consensus expert opinion and the criteria regarding IIM subtype assignments, resulting in a large proportion of criteria-assigned cases of PM having heterogeneous features. These results may have important implications for future use of these criteria in subsequent research.

The temporal relationship between cancer and adult onset anti-transcriptional intermediary factor 1 antibody-positive dermatomyositis.

OBJECTIVES: To characterize the 10 year relationship between anti-transcriptional intermediary factor 1 antibody (anti-TIF1-Ab) positivity and cancer onset in a large UK-based adult DM cohort. METHODS: Data from anti-TIF1-Ab-positive/-negative adults with verified diagnoses of DM from the UK Myositis Network register were analysed. Each patient was followed up until they developed cancer. Kaplan-Meier methods and Cox proportional hazard modelling were employed to estimate the cumulative cancer incidence. RESULTS: Data from 263 DM cases were analysed, with a total of 3252 person-years and a median 11 years of follow-up; 55 (21%) DM cases were anti-TIF1-Ab positive. After 10 years of follow-up, a higher proportion of anti-TIF1-Ab-positive cases developed cancer compared with anti-TIF1-Ab-negative cases: 38% vs 15% [hazard ratio 3.4 (95% CI 2.2, 5.4)]. All the detected malignancy cases in the anti-TIF1-Ab-positive cohort occurred between 3 years prior to and 2.5 years after DM onset. No cancer cases were detected within the following 7.5 years in this group, whereas cancers were detected during this period in the anti-TIF1-Ab-negative cases. Ovarian cancer was more common in the anti-TIF1-Ab-positive vs -negative cohort: 19% vs 2%, respectively (P < 0.05). No anti-TIF1-Ab-positive case <39 years of age developed cancer, compared with 21 (53%) of those ≥39 years of age. CONCLUSION: Anti-TIF1-Ab-positive-associated malignancy occurs exclusively within the 3 year period on either side of DM onset, the risk being highest in those ≥39 years of age. Cancer types differ according to anti-TIF1-Ab status, and this may warrant specific cancer screening approaches.

Validation of the Psoriatic Arthritis Impact of Disease (PsAID) Questionnaire and its potential as a single-item outcome measure in clinical practice.

OBJECTIVES: The Psoriatic Arthritis Impact of Disease (PsAID) Questionnaire is a recently developed patient-reported outcome measure (PROM) of disease impact in psoriatic arthritis (PsA). We set out to assess the validity in an independent cohort of patients, estimate the minimally important difference for improvement and explore the potential of individual components of the PsAID in clinical practice. METHODS: Data were collected prospectively for a single-centre cohort of patients with PsA. Construct validity was assessed by Spearman correlation with other PROMs and reliability by intraclass correlation coefficient (ICC) at 1 week. Sensitivity to change at 3 months was determined by the standardised response mean (SRM) in those patients with active disease requiring a change in treatment. RESULTS: A total of 129 patients (mean ±SD age 52.1±13.3, 57% women, disease duration 10.2±8 years) completed the baseline questionnaires and assessments. The mean baseline PsAID12 score was 3.92±2.26 with an ICC of 0.91 (95%CI 0.87 to 0.94). The SE of measurement was 0.51 and the minimal detectable change was 1.41. There was strong correlation (r≥0.70) with most of the PROMs studied and moderate correlation with clinical outcomes (r=0.40-0.57). The SRM of the PsAID12 was 0.74 (95%CI 0.45 to 0.97). There was strong correlation with individual PsAID items and their corresponding PROM questionnaires (r≥0.67). CONCLUSION: The PsAID is a reliable, feasible and discriminative measure in patients with PsA. The good responsiveness of the PsAID and strong correlation of individual items with other PROMS represent an opportunity to reduce questionnaire burden for patients in studies and clinical practice.

Presence of anti-eukaryotic initiation factor-2B, anti-RuvBL1/2 and anti-synthetase antibodies in patients with anti-nuclear antibody negative systemic sclerosis.

Objectives: Autoantibodies targeting ubiquitously expressed nuclear antigens can be identified in most patients with SSc. Cytoplasmic autoantibodies (in otherwise ANA-negative sera) targeting eukaryotic initiation factor-2B (anti-eIF2B) have recently been identified in SSc with clinical associations to dcSSc disease and interstitial lung disease (ILD), although the majority of samples originated from a tertiary SSc-ILD centre. We investigated the prevalence and clinical associations of recently described SSc-specific (including anti-eIF2B) and other cytoplasmic autoantibodies in ANA-negative sera obtained from a large representative SSc cohort. Methods: ANA-negative sera from the Scleroderma Family Registry and DNA Repository underwent indirect immunofluorescence, radiolabelled protein immunoprecipitation (± immunodepletion) to identify anti-eIF2B and other CTD-related autoantibodies. The clinical phenotype of positive samples was evaluated. Results: Immunoprecipitation was performed on 128 ANA-negative samples (obtained from 3249 SSc patients). Anti-eIF2B antibodies were present in nine patients (7%), the majority of whom had dcSSc (8/9). SSc-ILD was present in all anti-eIF2B patients for whom chest imaging was available (7/9). Anti-synthetase autoantibodies (targeting PL12, PL7, OJ and Zo) were identified in seven patients (5.5%), all of whom fulfilled the 2013 ACR/EULAR classification criteria for SSc and had evidence of SSc-ILD where relevant outcomes were available for evaluation. Anti-RuvBL1/2 antibodies were identified in two patients with SSc-overlap syndromes. Conclusion: Anti-eIF2B antibodies are cytoplasmic SSc-specific autoantibodies with strong clinical associations with dcSSc and SSc-ILD found in ANA-negative sera. Anti-synthetase autoantibodies, and other recently discovered SSc-specific antibodies such as anti-RuvBL1/2, can also be identified in ANA-negative SSc.

Short-term efficacy and safety of rituximab therapy in refractory systemic lupus erythematosus: results from the British Isles Lupus Assessment Group Biologics Register.

Objectives: To describe the baseline characteristics of SLE patients requiring biologic therapy in the UK and to explore short term efficacy and infection rates associated with rituximab (RTX) use. Methods: Patients commencing biologic therapy for refractory SLE and who consented to join BILAG-BR were analysed. Baseline characteristics, disease activity (BILAG 2004/SLEDAI-2K) and rates of infection over follow-up were analysed. Response was defined as loss of all A and B BILAG scores to ⩽ 1 B score with no new A/B scores in other organ systems at 6 months. Results: Two hundred and seventy SLE patients commenced biologic therapy from September 2010 to September 2015, most commonly RTX (n = 261). Two hundred and fifty (93%) patients were taking glucocorticoids at baseline at a median [interquartile range (IQR)] oral dose of 10 mg (5-20 mg) daily. Response rates at 6 months were available for 68% of patients. The median (IQR) BILAG score was 15 (10-23) at baseline and 3 (2-12) at 6 months (P < 0.0001). The median (IQR) SLEDAI-2K reduced from 8 (5-12) to 4 (0-7) (P < 0.001). Response was achieved in 49% of patients. There was also a reduction in glucocorticoid use to a median (IQR) dose of 7.5 mg (5-12 mg) at 6 months (P < 0.001). Serious infections occurred in 26 (10%) patients, being more frequent in the first 3 months post-RTX therapy. A higher proportion of early infections were non-respiratory (odds ratio = 1.98, 95% CI: 0.99, 3.9; P = 0.049). Conclusion: RTX is safe and is associated with improvement in disease activity in refractory SLE patients with concomitant reductions in glucocorticoid use. Early vigilance for infection post-infusion is important to further improve treatment risks and benefits.

Axial Disease in Psoriatic Arthritis study: defining the clinical and radiographic phenotype of psoriatic spondyloarthritis.

OBJECTIVES: To compare the prevalence, clinical and radiographic characteristics of psoriatic spondyloarthritis (PsSpA) in psoriatic arthritis (PsA), with ankylosing spondylitis (AS). METHODS: A prospective single-centre cross-sectional observational study recruited consecutive PsA and AS cases. Participants completed outcome measures, and underwent clinical examination, axial radiographic scoring and HLA-sequencing. Multivariable analyses are presented. RESULTS: The 402 enrolled cases (201 PsA, 201 AS; fulfilling classification criteria for respective conditions) were reclassified based upon radiographic axial disease and psoriasis, as: 118 PsSpA, 127 peripheral-only PsA (pPsA), and 157 AS without psoriasis (AS) cases. A significant proportion of patients with radiographic axial disease had PsSpA (118/275; 42.91%), and often had symptomatically silent axial disease (30/118; 25.42%). Modified New York criteria for AS were fulfilled by 48/201 (23.88%) PsA cases, and Classification of Psoriatic Arthritis criteria by 49/201 (24.38%) AS cases. pPsA compared with PsSpA cases had a lower frequency of HLA-B*27 (OR 0.12; 95% CI 0.05 to 0.25). Disease activity, metrology and disability were comparable in PsSpA and AS. A significant proportion of PsSpA cases had spondylitis without sacroiliitis (39/118; 33.05%); they less frequently carried HLA-B*27 (OR 0.11; 95% CI 0.04 to 0.33). Sacroiliac joint complete ankylosis (adjusted OR, ORadj 2.96; 95% CI 1.42 to 6.15) and bridging syndesmophytes (ORadj 2.78; 95% CI 1.49 to 5.18) were more likely in AS than PsSpA. Radiographic axial disease was more severe in AS than PsSpA (Psoriatic Arthritis Spondylitis Radiology Index Score: adjusted incidence risk ratio 1.13; 95% CI 1.09 to 1.19). CONCLUSIONS: In a combined cohort of patients with either PsA or AS from a single centre, 24% fulfilled classification criteria for both conditions. The pattern of axial disease was influenced significantly by the presence of skin psoriasis and HLA-B*27.

Autoantibodies in juvenile-onset myositis: Their diagnostic value and associated clinical phenotype in a large UK cohort.

OBJECTIVES: Juvenile myositis is a rare and heterogeneous disease. Diagnosis is often difficult but early treatment is important in reducing the risk of associated morbidity and poor outcomes. Myositis specific autoantibodies have been described in both juvenile and adult patients with myositis and can be helpful in dividing patients into clinically homogenous groups. We aimed to explore the utility of myositis specific autoantibodies as diagnostic and prognostic biomarkers in patients with juvenile-onset disease. METHODS: Using radio-labelled immunoprecipitation and previously validated ELISAs we examined the presence of myositis specific autoantibodies in 380 patients with juvenile-onset myositis in addition to, 318 patients with juvenile idiopathic arthritis, 21 patients with juvenile-onset SLE, 27 patients with muscular dystrophies, and 48 healthy children. RESULTS: An autoantibody was identified in 60% of juvenile-onset myositis patients. Myositis specific autoantibodies (49% patients) were exclusively found in patients with myositis and with the exception of one case were mutually exclusive and not found in conjunction with another autoantibody. Autoantibody subtypes were associated with age at disease onset, key clinical disease features and treatment received. CONCLUSIONS: In juvenile patients the identification of a myositis specific autoantibody is highly suggestive of myositis. Autoantibodies can be identified in the majority of affected children and provide useful prognostic information. There is evidence of a differential treatment approach and patients with anti-TIF1γ autoantibodies are significantly more likely to receive aggressive treatment with IV cyclophosphamide and/or biologic drugs, clear trends are also visible in other autoantibody subgroups.

Estimating the diagnostic accuracy of rheumatoid factor in UK primary care: a study using the Clinical Practice Research Datalink.

OBJECTIVE: To investigate the diagnostic accuracy of RF as a test for RA in primary care and its impact on referral times using the Clinical Practice Research Datalink. METHODS: We identified all patients with a first RF test recorded in the Clinical Practice Research Datalink between 1 January 2000 and 31 December 2008 and those diagnosed with RA within 2 years of testing. We calculated likelihood ratios (LRs), sensitivity, specificity and predictive values of RF for a diagnosis of RA. We compared time to hospital referral in those testing positive and negative using Kaplan-Meier failure curves and log-rank tests. RESULTS: Of 62 436 first RF tests, 4679 (7.5%) were positive. There were 1753 incident cases of RA, of which 57.8% were seropositive. The positive LR for RF was 9.5 (95% CI 9.0, 10.0) and the negative LR was 0.5 (95% CI 0.4, 0.5). Sensitivity and specificity were 57.8% (95% CI 55.4%, 60.1%) and 93.9% (95% CI 93.7%, 94.1%) and the positive predictive value and negative predictive value were 21.4% (95% CI 20.3%, 22.6%) and 98.7% (95% CI 98.6%, 98.8%), respectively. Median time to first hospital contact after the first RF test in those with seropositive vs seronegative results was 54 days (95% CI 49, 58) vs 150 (95% CI 147, 152). CONCLUSION: Only 2.8% of patients undergoing RF testing were diagnosed with RA, suggesting that RF is used to screen patients with musculoskeletal symptoms rather than those with more specific features of RA. A positive RF test may be helpful in diagnosing RA in primary care but performs badly in excluding RA and may delay referral.