Autoantibodies against the NineTeen complex and U5 RNP in systemic sclerosis.

ObjectiveMultiple spliceosome components are known autoantigens in systemic sclerosis (SSc). Here we aim to identify new and characterize rare anti-spliceosomal autoantibodies in patients with SSc without known autoantibody specificity. MethodsSera that precipitated spliceosome subcomplexes, as detected by immunoprecipitation-mass spectrometry (IP-MS), were identified from a database of 106 patients with SSc without known autoantibody specificity. New autoantibody specificities were confirmed with immunoprecipitation-western blot. The IP-MS pattern of new anti-spliceosomal autoantibodies was compared with anti-U1 RNP-positive sera of patients with different systemic autoimmune rheumatic diseases and anti-SmD-positive sera of patients with systemic lupus erythematosus (n = 24). ResultsThe NineTeen Complex (NTC) was identified and confirmed as new spliceosomal autoantigen in one patient with SSc. U5 RNP, as well as additional splicing factors, were precipitated by the serum of another patient with SSc. The IP-MS patterns of anti-NTC and anti-U5 RNP autoantibodies were distinct from those of anti-U1 RNP- and anti-SmD-positive sera. Furthermore, there was no difference in IP-MS patterns between a limited number of anti-U1 RNP-positive sera of patients with different systemic autoimmune rheumatic diseases. ConclusionAnti-NTC autoantibodies are a new anti-spliceosomal autoantibody specificity, here first identified in a patient with SSc. Anti-U5 RNP autoantibodies are a distinct but rare anti-spliceosomal autoantibody specificity. All major spliceosomal subcomplexes have now been described as target of autoantibodies in systemic autoimmune diseases.

Identification of new telomere- and telomerase-associated autoantigens in systemic sclerosis.

PURPOSE: In up to 20% of patients with systemic sclerosis (SSc) no known autoantibody specificity can be identified. Recently discovered autoantigens, such as telomeric repeat binding factor 1 (TERF1), as well as established autoantigens, like RuvBL1/2, are associated with telomere and telomerase biology. We aimed to identify new telomere- and telomerase-associated autoantigens in patients with SSc without known autoantibody specificity. METHODS: Unlabelled protein immunoprecipitation combined with gel-free liquid chromatography-tandem mass spectrometry (IP-MS) was performed with sera of 106 patients with SSc from two tertiary referral centres that had a nuclear pattern on HEp-2 indirect immunofluorescence without previously identified autoantibody. Telomere- or telomerase-associated proteins or protein complexes precipitated by individual sera were identified. Candidate autoantigens were confirmed through immunoprecipitation-western blot (IP-WB). A custom Luminex xMAP assay for 5 proteins was evaluated with sera from persons with SSc (n = 467), other systemic autoimmune rheumatic diseases (n = 923), non-rheumatic disease controls (n = 187) and healthy controls (n = 199). RESULTS: Eight telomere- and telomerase-associated autoantigens were identified in a total of 11 index patients, including the THO complex (n = 3, all with interstitial lung disease and two with cardiac involvement), telomeric repeat-binding factor 2 (TERF2, n = 1), homeobox-containing protein 1 (HMBOX1, n = 2), regulator of chromosome condensation 1 (RCC1, n = 1), nucleolar and coiled-body phosphoprotein 1 (NOLC1, n = 1), dyskerin (DKC1, n = 1), probable 28S rRNA (cytosine(4447)-C(5))-methyltransferase (NOP2, n = 1) and nuclear valosin-containing protein-like (NVL, n = 2). A Luminex xMAP assay for THO complex subunit 1 (THOC1), TERF2, NOLC1, NOP2 and NVL revealed high reactivity in all index patients, but also in other patients with SSc and disease controls. However, the reactivity by xMAP assay in these other patients was not confirmed by IP-WB. CONCLUSION: IP-MS revealed key telomere- and telomerase-associated proteins and protein complexes as autoantigens in patients with SSc.

Off-label use of mycophenolate mofetil in the treatment of rare and complex rheumatic connective tissue diseases.

OBJECTIVES: We aimed to investigate the clinical off-label use of mycophenolate mofetil (MMF), including its safety and efficacy in patients with rare and complex rheumatic connective tissue diseases (rCTDs). METHODS: A survey was distributed across experts from ERN-ReCONNET reference centres in order to assess the experience with MMF off-label use. Patient-level data of patients with rCTDs under treatment with MMF was also collected for analysis of safety and efficacy. RESULTS: Twelve experts from eleven centres distributed throughout Europe (7 countries) answered the survey. The experience was concordant in that, despite of its off-label use, experts reported opting frequently for this therapeutic alternative with robust confidence on its efficacy and safety. The analysis of 108 patients with rCTDs under MMF revealed a good safety profile, as well as good clinical outcomes, especially for systemic lupus erythematosus and idiopathic inflammatory myopathies. The presence of interstitial lung disease was, as expected, associated with a worse clinical outcome despite use of MMF. CONCLUSIONS: MMF is widely used in reference centres for rCTDs. Its safety profile and efficacy seem to be recognised by experts and demonstrated with patient-level analysis. While selected rCTDs will likely remain an off-label indication for MMF, robust data seem to support this therapy as an appropriate alternative for safely and effectively treating many manifestations of rCTDs.

Clinical spectrum time course in non-Asian patients positive for anti-MDA5 antibodies.

OBJECTIVES: To define the clinical spectrum time-course and prognosis of non-Asian patients positive for anti-MDA5 antibodies. METHODS: We conducted a multicentre, international, retrospective cohort study. RESULTS: 149 anti-MDA5 positive patients (median onset age 53 years, median disease duration 18 months), mainly females (100, 67%), were included. Dermatomyositis (64, 43%) and amyopathic dermatomyositis (47, 31%), were the main diagnosis; 15 patients (10%) were classified as interstitial pneumonia with autoimmune features (IPAF) and 7 (5%) as rheumatoid arthritis. The main clinical findings observed were myositis (84, 56%), interstitial lung disease (ILD) (108, 78%), skin lesions (111, 74%), and arthritis (76, 51%). The onset of these manifestations was not concomitant in 74 cases (50%). Of note, 32 (21.5%) patients were admitted to the intensive care unit for rapidly progressive-ILD, which occurred in median 2 months from lung involvement detection, in the majority of cases (28, 19%) despite previous immunosuppressive treatment. One-third of patients (47, 32% each) was ANA and anti-ENA antibodies negative and a similar percentage was anti-Ro52 kDa antibodies positive. Non-specific interstitial pneumonia (65, 60%), organising pneumonia (23, 21%), and usual interstitial pneumonia-like pattern (14, 13%) were the main ILD patterns observed. Twenty-six patients died (17%), 19 (13%) had a rapidly progressive-ILD. CONCLUSIONS: The clinical spectrum of the anti-MDA5 antibodies-related disease is heterogeneous. Rapidly-progressive ILD deeply impacts the prognosis also in non-Asian patients, occurring early during the disease course. Anti-MDA5 antibody positivity should be considered even when baseline autoimmune screening is negative, anti-Ro52 kDa antibodies are positive, and radiology findings show a NSIP pattern.

Pitfalls in the detection of myositis specific antibodies by lineblot in clinically suspected idiopathic inflammatory myopathy.

OBJECTIVES: Today, the contribution of myositis-specific autoantibodies (MSA) in the diagnostic workup of idiopathic inflammatory myopathies (IIM) is on the rise. The aim of this study was to document MSA frequency as detected by lineblot in a set of consecutive MSA requests and to correlate the results with clinical diagnosis, IIM subtype and indirect immunofluorescence (IIF) findings. Additionally, a comparison between two lineblots was performed. METHODS: A total of 118 consecutive samples of patients with suspicion of IIM were analysed on IIF and two lineblots. A total of 107 patients with autoimmune rheumatic diseases served as controls. RESULTS: MSA were detected in 55% of IIM patients (n=31) and 7.9% (n=12) of patients without clinical diagnosis of IIM or myositis overlap syndrome. All the IIM patients had a MSA-compatible clinical subtype. There was no to fair agreement between both lineblots for the individual antibodies, with most discrepancies observed for anti-TIF1γ (κ=-0.021), anti-SRP (κ=-0.006) and anti-SAE (κ=0.395). Differences between both assays were mostly observed in the non-IIM patients, also showing signi cantly lower blot signal intensities compared to IIM patients (p=0.0013). MSA in the non-IIM patients frequently showed an incompatible IIF pattern. CONCLUSIONS: Lineblot seems to be an interesting tool for MSA detection in a clinical context, allowing the identification of clinical subtypes. However, considerable caution must be exercised in interpreting the results in case of low positive MSA signal intensity, discordant lineblot results and/or an incompatible IIF pattern.

A prospective, longitudinal study evaluating the baseline six-minute walk test as an individual reference value in systemic sclerosis patients.

OBJECTIVES: Interstitial lung disease (ILD) and pulmonary arterial hypertension (PAH) are the leading causes of death in systemic sclerosis (SSc). Although the six-minute walk test (6MWT) is used for evaluating ILD and PAH, no data are available on the evolution of the six-minute walk distance (6MWD) in SSc patients without ILD and PAH and whether the baseline 6MWD could serve as individual reference value for the management of those who will develop PAH or ILD. METHODS: Prospectively collected data of the first 6MWT (at baseline or 6-month follow-up) and the 6MWTs at 18-, 30-, 42-, 54-, and 66-month visit of 165 consecutive SSc patients without ILD and PAH, included in the Ghent University SSc Cohort between May 2006 and December 2016 were analysed. RESULTS: 96-100% of the included patients performed a 6MWT during the follow-up visits. The mean 6MWD during the baseline 6MWT of 165 SSc patients without ILD and PAH (35% limited, 56% limited cutaneous, 9% diffuse cutaneous SSc) was 484.20+/-92.65m with no significant difference in the 6MWD at different follow-up visits as compared to baseline. In 46 SSc patients without ILD and PAH who performed a 6MWT at baseline and at 66-month visit, the 6MWD walked at 66-month visit correlated with the baseline 6MWD (r=0.564, p<0.001). CONCLUSIONS: In SSc without ILD and PAH, the 6MWT is feasible and the 6MWD is clinically stable over a 66 months period. Hence, the individual 6MWD might be used as individual reference value in management of those who will develop PAH or ILD.

The importance of detecting anti-DFS70 in routine clinical practice: comparison of different care settings.

BACKGROUND: Screening for antinuclear antibodies by indirect immunofluorescence (ANA-IIF) is essential in the diagnostic workup of ANA-associated autoimmune rheumatic diseases (AARDs). However, also healthy individuals may test positive, making the interpretation challenging. Recent reports suggest that dense fine speckled 70 antibodies (anti-DFS70) may facilitate this challenge. Here, we investigate their clinical importance based on data from four Belgian laboratories (one primary, two secondary and one tertiary care). METHODS: At least one specific DFS70 assay (DFS70 IgG ELISA or lineblot [Euroimmun, full length antigen] and/or DFS70 IgG CLIA [Inova Diagnostics, truncated antigen]) was performed on four consecutive cohorts of homogeneous-like ANA-IIF samples (n=697). Co-occurrence with AARD-specific ANA and clinical information were documented in the anti-DFS70-positive samples. RESULTS: Using a combination of solid phase techniques, we found between 7.6% and 26% anti-DFS70 in the different cohorts. Focusing on anti-DFS70 CLIA-positive samples without co-occurrence of AARD-specific ANA, we observed a trend towards lower frequency in tertiary (8% [p=0.0786]) and secondary care (12% [p=0.1275] and 6% [p<0.001]) compared to primary care (21%). Moreover, in this specific subpopulation, AARD was less frequent (0%-50% compared to 6%-77% in the total anti-DFS70-positive group). CONCLUSIONS: Anti-DFS70 prevalence depends on the applied assay and care setting. Our data suggest that, for an ANA-IIF-positive patient, it is rather the absence of AARD-associated ANA and clinical symptoms that contribute to the exclusion of AARD than the presence of anti-DFS70. Nevertheless, isolated anti-DFS70 helps to clarify positive ANA-IIF results, especially if pretest probability for AARD is low.

Screening for pulmonary arterial hypertension in an unselected prospective systemic sclerosis cohort.

Screening for pulmonary arterial hypertension (PAH) in systemic sclerosis (SSc) improves outcomes. The DETECT screening algorithm is recommended in a high-risk SSc subgroup. This study aims to compare prospectively the positive predictive value of screening using the DETECT algorithm and the 2009 European Society of Cardiology/European Respiratory Society (ESC/ERS) guidelines, and to compare their cost-effectiveness in an unselected, day-to-day SSc population. Post hoc, screening according to the 2015 ESC/ERS guidelines using echocardiographic parameters alone ("2015 echo screening") or combined with the DETECT algorithm ("2015 combined screening") in high-risk subjects was analysed.195 consecutive SSc patients included in the Ghent University Hospital SSc cohort were screened using different algorithms.The referral rate for right heart catheterisation was 32% (63 out of 195 patients) (46/4/13/34/40 patients using the DETECT algorithm/2009 guidelines/both/2015 echo screening/2015 combined screening). Right heart catheterisation was performed in 53 patients (84%) (36 (78%)/four (100%)/13 (100%)/28 (82%)/32 (80%) patients recommended by the DETECT algorithm/2009 guidelines/both/2015 echo screening/2015 combined screening). PAH was diagnosed in three patients (incidence 1.5%·year-1, 95% CI 0.5-4.4), in whom all algorithms recommended a right heart catheterisation. The positive predictive value was 6% (95% CI 2-17%; three out of 49 patients) for the DETECT algorithm, 18% (95% CI 6-41%; three out of 17 patients) for the 2009 guidelines, 23% (95% CI 8-50%; three out of 13 patients) for both, 11% (95% CI 4-27%; three out of 28 patients) for the 2015 echo screening and 9% (95% CI 3-24%; three out of 32 patients) for the 2015 combined screening. The cost was EUR224/80/90/112 per patient using the DETECT algorithm/2009 guidelines/2015 echo screening/2015 combined screening.Echocardiography may remain a candidate first step for PAH screening in SSc.

Six-minute walk test in or out in evaluation of systemic sclerosis patients?

OBJECTIVES: Interstitial lung disease (ILD) and pulmonary arterial hypertension (PAH) are the leading causes of death in systemic sclerosis (SSc) patients. Although the six-minute walk test (6MWT) is used for evaluating ILD and PAH in clinical practice, no data are available on six-minute walk distance (6MWD) and oxygen desaturation in SSc patients without ILD and PAH. METHODS: Prospectively collected data of the 6MWTs at baseline and 6-month follow-up of 300 consecutive SSc patients, included in the Ghent University Hospital Systemic Sclerosis Unit between May 2006 and April 2015 were analysed. RESULTS: The mean 6MWD of 165 SSc patients without ILD and PAH who performed a 6MWT at baseline or at the 6-month visit was 484±93m. Patients in the diffuse cutaneous (DcSSc) subgroup (435±94m) walked less than in the limited (LSSc) subgroup (499±91m, p=0.04) and tended to walk less than in the limited cutaneous (LcSSc) subgroup (483±92m, p=0.15). In 115 SSc patients without ILD and PAH who walked at both moments, there was no significant difference between the 6MWDs (mean difference -7.60m 95%CI [-19.93m; 4.73m], p=0.23) and the oxygen desaturation was not statistically different in 102 of them (mean difference 0.41% 95%CI [-0.49%; 1.31%], p=0.37). CONCLUSIONS: In SSc without ILD and PAH, the 6MWD and oxygen desaturation is clinically stable over a 6 months period. The DcSSc subgroup walks less than the LSSc and the LcSSc subgroup.

Nailfold Capillaroscopy and Clinical Applications in Systemic Sclerosis.

Capillary microscopy is a safe and non-invasive tool to evaluate the morphology of the microcirculation typically affected in SSc. Next to being paramount for the "(very) early" diagnosis of SSc eyes are also geared toward capillaroscopy with the aim to be able to use it as a biomarker, especially in the prediction of future occurrence of DU. The following review will explain what capillary microscopy is and will focus additionally on studies evaluating the association between capillaroscopy and DU.

Disease activity indices in systemic sclerosis: a systematic literature review.

OBJECTIVES: Reviewing disease activity indices (DAI) in systemic sclerosis (SSc) and reporting their validation status. METHODS: Literature was systematically reviewed on studies documenting the development of DAI, assessing the validation status of DAI and studies using a DAI in their analysis. The qualitative and quantitative validation status of existing DAI was assessed based on OMERACT and on definitions of the American College of Rheumatology (ACR) committee on quality measures. RESULTS: Three DAI in SSc have been proposed in literature: the European Scleroderma Study Group (EScSG) activity index, the 12-point DAI and the Combined Response Index for Systemic Sclerosis (CRISS). The EScSG activity index is yet applied as an outcome measure in 48 different studies. The EScSG activity index and the CRISS are provisional partially validated DAI. CONCLUSIONS: Future studies are needed to fully validate the EScSG activity index and the CRISS and to assess the validation status of the 12-point DAI.

Assessment of sensitivity to change of the European Scleroderma Study Group activity index.

OBJECTIVES: The European Scleroderma Study Group (EScSG) activity index meets nearly all the OMERACT-standards of truth, discrimination and feasibility. The sensitivity to change remains to be attested. This study assesses sensitivity to change of the EScSG activity index in patients with early and severe diffuse cutaneous Systemic Sclerosis (dcSSc) treated with rituximab. METHODS: 12-month follow-up (open-label study) of 14 consecutive patients with early dcSSc. Patients received an infusion of two times 1000 mg rituximab at month 0 and 6, together with 100 mg methylprednisolone. Clinical read outs (modified Rodnan skin score [mRSS], lung function and echocardiography) and EScSG activity index were performed at month 0, 3, 6 and 12. Mixed models analyses (MMA) were used to evaluate changes in parameters over time. RESULTS: There was a clinically significant change in skin score with a mean (SD) mRSS of 24.8 (4.44) at baseline and 10.4 (3.12) at month 12 (MMA p<0.001). Also the EScSG activity index decreased significantly, with a mean (SD) of 4.3 (1.79) at baseline and 0.7 (0.83) at month 12 (MMA p<0.001). The estimated mean change of the EScSG activity index was -3.6 (95%CI -4.9; -2.4) over 12 months. Indices of internal organ involvement remained stable throughout the study. CONCLUSIONS: A significant improvement of the EScSG activity index was observed, in line with the significant improvement of the mRSS and the stabilisation of internal organ involvement. To our knowledge, this is the first study to attest sensitivity to change of the EScSG activity index in the subset of 'early' dcSSc. TRIAL REGISTRATION: ClinicalTrials.gov Registration, http://clinicaltrials.gov, number NCT00379431.

IgG4-related disease: The utility of (18)F-FDG PET/CT in diagnosis and treatment.

OBJECTIVE: IgG4-related disease (IgG4-RD) is a systemic mass-forming fibro-inflammatory condition which can affect nearly every organ system. Its pathophysiology remains incompletely understood, but affected tissues are characterized by a lymphoplasmacytic infiltrate rich in IgG4-positive plasma cells which cause chronic inflammation, storiform fibrosis and phlebitis. These findings on histopathological specimens are considered the gold standard for the diagnosis. Clinical signs and symptoms largely depend upon organ involvement which can be singular or multiple, synchronous or metachronous. The organs most frequently involved are the pancreas (autoimmune pancreatitis (AIP), salivary and lacrimal glands (Mickulicz disease and sclerosing sialadenitis), biliary tree (sclerosing cholangitis or cholecystitis), retroperitoneum (retroperitoneal fibrosis), aorta (periaortic fibrosis), kidneys (interstitial nephritis) and thyroid (Riedel thyroiditis). Presentation is mostly subacute and general symptoms such as weight loss, asthenia or fever are moderate, but more prevalent in multi-organ disease. Lesions often mimic malignancy, but most respond well to steroid therapy. CONCLUSION: In this contribution we present a rare entity of IgG4-RD and discuss the utility of fluorine-18-fluorodeoxyglucose ((18)F-FDG) Positron emission tomography/computed tomography (PET/CT) in the diagnosis and treatment of this condition.

Positioning of myositis-specific and associated autoantibody (MSA/MAA) testing in disease criteria and routine diagnostic work-up.

Nowadays, the importance of detection of myositis-specific antibodies (MSA) and myositis-associated antibodies (MAA) in diagnosis and in delineating disease subsets of idiopathic inflammatory myopathy (IIM) is highly acknowledged by IIM experts. Consequently, MSA/MAA are increasingly integrated in expert-based myositis (sub)classification criteria as well as in routine diagnostics. In contrast, MSA/MAA are under-represented in data-based (sub)classification criteria, mostly related to the lack of sufficient data on the wide spectrum of MSA/MAA in large multicenter cohorts. Unfortunately, the current commercially available assays to detect MSA/MAA show variable analytical and clinical performance characteristics. This challenges the design of prospective multicenter studies on MSA/MAA as well as the optimization of their routine clinical use. Additional validation studies and continuous harmonization initiatives on MSA/MAA detection from the pre-analytical to the post-analytical phase (e.g. from defining request criteria to guidelines for reporting), will be needed to overcome these hurdles. To speed up this process, we encourage close collaborations between IIM clinical experts, laboratory professionals and diagnostic companies.

Standardised interpretation of capillaroscopy in autoimmune idiopathic inflammatory myopathies: A structured review on behalf of the EULAR study group on microcirculation in Rheumatic Diseases.

OBJECTIVE: We conducted a systematic review, on behalf of the EULAR Study Group on Microcirculation in Rheumatic Diseases (EULAR SG MC/RD), to investigate the value of nailfold videocapillaroscopy (NVC) in idiopathic inflammatory myopathies (IIM). METHODS: Three electronic databases were systematically searched to find all relevant manuscripts reporting NVC outcomes in IIM patients. Articles were assessed based on study design, population, NVC methodology and description of NVC results. To allow comparison between the articles, all NVC results were interpreted according to standardised capillaroscopic terminology, as previously consented by the EULAR SG MC/RD and the Scleroderma Clinical Trials Consortium (SCTC) Group on Capillaroscopy. RESULTS: Of the 653 identified records; five were retained after critical appraisal on title, abstract and manuscript level. A marked difference in NVC was observed between (juvenile) dermatomyositis [(j)DM] versus polymyositis, healthy controls and systemic sclerosis patients. In addition, reduced capillary density and scleroderma pattern seem to be associated with active disease in (j)DM, while immunosuppressive treatment appears to reduce NVC abnormalities. CONCLUSION: This is the first systematic review investigating NVC in IIM, interpreting the results according to an international consented standardised manner, as proposed by the EULAR SG MC/RD and SCTC Group on Capillaroscopy. We can conclude that NVC presents a promising asset in the diagnosis of (j)DM. Moreover, NVC could be a biomarker for organ involvement and follow-up. Large multicentre prospective standardised studies are further needed to definitely describe associations with clinical and laboratory parameters in the different IIM subtypes.

Treat-to-target in rheumatoid arthritis: a real-world study of the application and impact of treat-to-target within the wider context of patient management, patient centricity and advanced therapy use in Europe.

BACKGROUND: While treat-to-target (T2T) is endorsed for the management of rheumatoid arthritis (RA), data on the degree of implementation in clinical practice are limited. This study investigated the use of T2T for RA in a real-world setting across Europe. METHODS: The Adelphi RA Disease-Specific Programme was a point-in-time survey of rheumatologists and their consulting patients with RA conducted between January and October 2020 in Belgium, France, Germany, Italy, Spain and the UK. Rheumatologists completed an attitudinal survey, and a record form for their next 10-12 consulting patients, who were invited to voluntarily complete a patient-reported questionnaire. Data collected included clinical characteristics, treatment patterns and attitudes towards T2T. RESULTS: Overall, 316 rheumatologists provided data for 3120 patients, of whom 1108 completed the questionnaire. While 86.1% of rheumatologists estimated using T2T principles in clinical practice, only 66.6% of patients were reported by their physician to be managed using a T2T approach. Achieving disease remission was the most commonly reported treatment goal identified by rheumatologists (79.7%), followed by symptom control (47.8%) and reducing impact on quality of life (44.5%). 40.8% of rheumatologists and their patients were in agreement that a treatment goal had been set. When there was agreement on treatment goals, we observed better patient satisfaction, engagement and treatment success. CONCLUSIONS: Despite recommendations, the T2T approach in RA appears to be suboptimally implemented in clinical practice. This highlights the importance of patient-centricity in the decision-making process to define meaningful targets and select appropriate treatments to improve disease outcomes.

Incidence, prevalence and long-term progression of Goh algorithm rated interstitial lung disease in systemic sclerosis in two independent cohorts in flanders: A retrospective cohort study.

OBJECTIVES: The epidemiology of interstitial lung disease (ILD) in systemic sclerosis (SSc) in Belgium is unknown. In literature, its prevalence varies between 19% and 52% in limited/diffuse cutaneous SSc (LcSSc/DcSSc). However, its prevalence in "early" SSc (pre-clinically overt SSc without [yet] skin involvement), nor its incidence rate in SSc (LcSSc/DcSSc/"early" SSc) has ever been described. Against this background, we aimed to determine the prevalence/incidence (rate) and progression of ILD in SSc. METHODS: 12-year follow-up data of consecutive SSc patients, included in two Flemish cohorts (University Hospitals Ghent and Leuven), were retrospectively analysed. ILD was classified according to the simplified Goh algorithm. Progression of ILD was defined as a relative decline of FVC ≥10%, a combined relative decline of FVC 5-10% and DLCO ≥15%, or as an increase in HRCT extent. RESULTS: 722 patients (60% LcSSc/ 20% DcSSc/ 20% "early" SSc, median (IQR) follow-up 39 [12-80] months) had baseline HRCT. 243 were rated to have ILD at baseline and 39 during follow-up (prevalence of 34%/ incidence rate of 20.3/1000PY, 95%CI:14.5-27.8). Amongst those with baseline ILD, 60% had lung functional progression at five years of follow-up. In the "early" SSc subgroup, eight patients were rated to have ILD at baseline and three during follow-up (prevalence of 6%/ incidence rate of 5.8/1000 PY, 95%CI:1.2-17.0). CONCLUSION: Both LcSSc and DcSSc patients should be monitored for ILD evolution. The low prevalence and incidence of ILD in the "early" SSc subgroup may instruct future decisions on the construction of uniform patient follow-up pathways in "early" SSc.