Systemic sclerosis in Asians: Are there racial differences?

Predictive factors for interstitial lung disease progression in a Singapore systemic sclerosis cohort: a multicentre study

INTRODUCTION

Interstitial lung disease (ILD) in systemic sclerosis (SSc) is heterogeneous with varied progression rate. This study aimed to identify the baseline clinical characteristics associated with ILD progression within 1, 3 and 5 years of the diagnosis of ILD.

METHODS

This was a prospective, multicentre study - Systematic Sclerosis Cohort Singapore - conducted from January 2008 to February 2021, which included SSc patients with ILD diagnosed by high-resolution computed tomography. Progression of ILD was defined by forced vital capacity (FVC) decline ≥10% predicted or FVC decline 5%-9% predicted, with diffusing lung capacity of carbon monoxide decline ≥15% from the time of ILD diagnosis. Multivariable logistic and Cox regression analyses, adjusting for malignancy and treatment, were performed to determine independent risk factors of ILD progression.

RESULTS

Of 124 SSc patients with ILD, 47.6% had limited cutaneous SSc, 33.9% had diffuse SSc and 18.5% had SSc-overlap. Progression of ILD was seen in 6%, 15% and 23% of patients within 1, 3 and 5 years, respectively. After adjusting for malignancy and treatment, anti-La was associated with ILD progression within 1 year (odds ratio [OR] 6.94, 95% confidence interval [CI]: 1.14-42.2; P = 0.04) and 3 years (OR 5.98, 95% CI: 1.31-27.4; P = 0.02), and anti-Scl-70 was associated with ILD progression within 5 years (OR 2.54, 95% CI: 1.05-6.12; P = 0.04). Analysing time to ILD progression as an outcome, anti-La was significantly associated with higher risk of ILD progression (hazard ratio 3.47, 95% CI: 1.18-10.2; P = 0.02). Time to ILD progression was 1.4 years in patients with anti-La versus 6.9 years in patients without anti-La (P = 0.02), and 4.7 years in patients with anti-Scl-70 versus 8.9 years in patients without anti-Scl-70 (P = 0.12).

CONCLUSION

In this Asian cohort of SSc patients, autoantibodies may help to predict ILD progression rates.

Exploratory clinical subgroup clustering in systemic sclerosis: Results from the Indian Progressive Systemic Sclerosis Registry

Objective

To conduct an exploratory cluster analysis of systemic sclerosis patients from the baseline data of the Indian systemic sclerosis registry.

Methods

Patients satisfying American College of Rheumatology-European League Against Rheumatism classification criteria for systemic sclerosis were included. The clusters formed using clinical and immunological parameters were compared.

Results

Of the 564 systemic sclerosis registry participants, 404 patients were included. We derived four clusters of which three were anti-topoisomerase I predominant and one was anti-centromere antibody 2 dominant. Cluster 1 (n-82 (20.3%)) had diffuse cutaneous systemic sclerosis patients with the most severe skin disease, anti-topoisomerase I positivity, males, younger age of onset and high prevalence of musculoskeletal, vasculopathic and gastrointestinal features. Cluster 2 (n-141 (34.9%)) was also diffuse cutaneous systemic sclerosis and anti-topoisomerase I predominant but with less severe skin phenotype than cluster 1 and a lesser prevalence of musculoskeletal, vasculopathic and gastrointestinal features. Cluster 3 (n-119 (29.5%)) had limited cutaneous systemic sclerosis patients with anti-topoisomerase I positivity along with other antibodies. The proximal muscle weakness was higher and digital pitting scars were lower, while other organ involvement was similar between clusters 2 and 3. Cluster 4 (n-62 (15.30%)) was the least severe group with limited cutaneous systemic sclerosis and anti-centromere antibody predominance. Age of onset was higher with low musculoskeletal disease and a higher presence of upper gastrointestinal features. The prevalence of interstitial lung disease was similar in the three anti-topoisomerase I predominant clusters.

Conclusion

With exploratory cluster analysis, we confirmed the possibility of subclassification of systemic sclerosis along a spectrum based on clinical and immunological characteristics. We also corroborated the presence of anti-topoisomerase I in limited cutaneous systemic sclerosis and the association of interstitial lung disease with anti-topoisomerase I.

GWAS for systemic sclerosis identifies six novel susceptibility loci including one in the Fcγ receptor region

Here we report the largest Asian genome-wide association study (GWAS) for systemic sclerosis performed to date, based on data from Japanese subjects and comprising of 1428 cases and 112,599 controls. The lead SNP is in the FCGR/FCRL region, which shows a penetrating association in the Asian population, while a complete linkage disequilibrium SNP, rs10917688, is found in a cis-regulatory element for IRF8. IRF8 is also a significant locus in European GWAS for systemic sclerosis, but rs10917688 only shows an association in the presence of the risk allele of IRF8 in the Japanese population. Further analysis shows that rs10917688 is marked with H3K4me1 in primary B cells. A meta-analysis with a European GWAS detects 30 additional significant loci. Polygenic risk scores constructed with the effect sizes of the meta-analysis suggest the potential portability of genetic associations beyond populations. Prioritizing the top 5% of SNPs of IRF8 binding sites in B cells improves the fitting of the polygenic risk scores, underscoring the roles of B cells and IRF8 in the development of systemic sclerosis. The results also suggest that systemic sclerosis shares a common genetic architecture across populations.

Epidemiology of the idiopathic inflammatory myopathies

The idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of systemic autoimmune diseases that affect the skeletal muscles and can also involve the skin, joints, lungs and heart. The epidemiology of IIM is obscured by changing classification criteria and the inherent shortcomings of case identification using healthcare record diagnostic coding. The incidence of IIM is estimated to range from 0.2 to 2 per 100,000 person-years, with prevalence from 2 to 25 per 100,000 people. Although the effects of age and gender on incidence are known, there is only sparse understanding of ethnic differences, particularly in indigenous populations. The incidence of IIM has reportedly increased in the twenty-first century, but whether this is a genuine increase is not yet known. Understanding of the genetic risk factors for different IIM subtypes has advanced considerably. Infections, medications, malignancy and geography are also commonly identified risk factors. Potentially, the COVID-19 pandemic has altered IIM incidence, although evidence of this occurrence is limited to case reports and small case series. Consideration of the current understanding of the epidemiology of IIM can highlight important areas of interest for future research into these rare diseases.

Reporting and Representativeness of Race, Ethnicity, and Socioeconomic Status in Systemic Sclerosis Randomized Trials: An Observational Study

OBJECTIVE

To assess how and to what extent socioeconomic status and ethnicity/race of participants are reported in randomized controlled trials (RCTs) on systemic sclerosis (SSc), and to estimate the representativeness of different ethnic/racial groups in SSc RCTs.

METHODS

We searched all published RCTs on SSc indexed in PubMed. We retrieved information on main features of RCTs published from 2000 onward and recorded for each study whether race/ethnicity was reported; how ethnicity/race was defined and assigned; and the number of patients included for each racial/ethnic group. Multivariable logistic regression was used to identify factors associated with race/ethnicity reporting. Proportion of races/ethnicities included in US-based RCTs on SSc was examined and compared with US demographic data.

RESULTS

We included 106 studies, mostly conducted in Europe (42%) or North America (25%), published after 2010 (74%), and enrolling a total of 6,693 patients. About one-third of studies provided information about race/ethnicity, with no improved reporting over time. Only 2 papers reported patient's socioeconomic status. Study location (US or intercontinental) was the only significant factor associated with a better reporting of race/ethnicity in multivariable analysis. In studies where race/ethnicity was reported, White patients were mostly represented (79%), followed by Asian (7%), and African American (6%). In the sensitivity analysis limited to studies from the US, underrepresentation of African American patients was observed in the 2000-2010 time period, but not later.

CONCLUSION

Documentation of race/ethnicity and socioeconomic status is poor in RCTs on SSc. More effort should be made to document race/ethnicity and socioeconomic status and to promote diversity in SSc RCTs.

Clinical and serological correlation of systemic sclerosis in Moroccan patients

Objective

SSc is a CTD characterized by excessive fibrosis of the skin and internal organs, along with microvascular damage, and is often associated with typical autoantibodies. The aim of this study was to analyse the correlation between specific autoantibody profiles, clinical and paraclinical features in Moroccan patients with SSc.

Methods

We analysed the presence of specific autoantibodies in 46 SSc patients using IIF on HEp-2 cells and immunodot. We then correlated the types of autoantibodies with clinical and laboratory manifestations.

Results

Among our patients, 86.9% were females. The mean age of patients at diagnosis was 50.21 years, with an average delay to diagnosis of 5 years. The main clinical manifestations found were RP (89.2%), sclerodactyly (84.8%), proximal scleroderma (67.4%), gastrointestinal involvement (50%) and interstitial lung disease (30.4%). According to the specific autoantibody profile, 14 patients were anti-topo I positive (30.4%), 8 anti-RNP (68 kDa/A/C) positive (17.4%) and 6 anti-RNA polymerase III positive (13%). We found a significant association of anti-RNA polymerase III with sclerodactyly and pulmonary arterial hypertension (P < 0.05). We also found an association between anti-topo I and interstitial lung disease in 30.4% of patients. There was no significant association between the positivity for the autoantibodies and other diagnosed clinical manifestations.

Conclusion

Some clinical manifestations of SSc might be positively correlated with the presence of specific autoantibodies. Environmental factors, ethnicity and gene interaction might also influence this correlation.

Functional disability and health-related quality of life among systemic sclerosis patients in Bangladesh

Objective

To assess the relationship between functional disability and health-related quality of life (HRQoL) among systemic sclerosis (SSc) patients.

Methodology

This cross-sectional study was carried out on 78 adults who met the classification criteria for SSc defined by the American College of Rheumatology/European League of Rheumatology (ACR/EULAR)-2013. The Bangla version of Short Form 36 (SF-36) and Health Assessment Questionnaire-Disability Index (HAQ-DI) were used to measure HRQoL and functional disability in SSc patients.

Results

The patients' median [IQR] HAQ-DI was 1.4 [0.6–2.1], with 37.2% having a mild functional disability, 33.3 percent having a moderate functional disability, and 29.5 percent having a severe functional disability. The hygiene and activity domains of the HAQ-DI obtained the highest scores, 2.0 [0.0–3.0] and 2.0 [1.0–3.0], respectively. The Physical Component Summary (PCS) and Mental Component Summary (MCS) of the SF-36 had median [IQR] values of 26.2 [15.0–58.1] and 42.0 [19.6–60.6]. The highest score was 50.0 [25.0–75.0] in social functioning. The PCS of the SF-36 was moderately correlated with the HAQ-DI (r_s = − 0.629, P < 0.001) and the MCS of the SF-36 was weakly correlated with the HAQ-DI ((r_s = − 0.344, P < 0.001). Age, female sex, and incomplete fist closure substantially influenced functional status. Calcinosis, Raynaud's Phenomenon, and flexion contracture significantly diminished the quality of life.

Conclusions

Functional disability negatively affects health-related quality of life. Age, Musculoskeletal, and skin involvement are significantly associated with poor quality of life and functional disability. Therefore, treatment strategies should be aimed at reducing functional disability, which will enhance the HRQoL of SSc patients.