Clinical prediction of 5-year survival in systemic sclerosis: validation of a simple prognostic model in EUSTAR centres

OBJECTIVE

Systemic sclerosis (SSc) is associated with a significant reduction in life expectancy. A simple prognostic model to predict 5-year survival in SSc was developed in 1999 in 280 patients, but it has not been validated in other patients. The predictions of a prognostic model are usually less accurate in other patients, especially from other centres or countries. A study was undertaken to validate the prognostic model to predict 5-year survival in SSc in other centres throughout Europe.

METHODS

A European multicentre cohort of patients with SSc diagnosed before 2002 was established. Patients with SSc according to the preliminary American College of Rheumatology classification criteria were eligible for the study when they were followed for at least 5 years or shorter if they died. The primary outcome was 5-year survival after diagnosis of SSc. The predefined prognostic model uses the following baseline variables: age, gender, presence of urine protein, erythrocyte sedimentation rate (ESR) and carbon monoxide diffusing capacity (DLCO).

RESULTS

Data were available for 1049 patients, 119 (11%) of whom died within 5 years after diagnosis. Of the patients, 85% were female, the mean (SD) age at diagnosis was 50 (14) years and 30% were classified as having diffuse cutaneous SSc. The prognostic model with age (OR 1.03), male gender (OR 1.93), urine protein (OR 2.29), elevated ESR (1.89) and low DLCO (OR 1.94) had an area under the receiver operating characteristic curve of 0.78. Death occurred in 12 (2.2%) of 509 patients with no risk factors, 45 (13%) of 349 patients with one risk factor, 55 (33%) of 168 patients with two risk factors and 7 (30%) of 23 patients with three risk factors.

CONCLUSION

A simple prognostic model using three disease factors to predict 5-year survival at diagnosis in SSc showed reasonable performance upon validation in a European multicentre study.

NLRP1 influences the systemic sclerosis phenotype: a new clue for the contribution of innate immunity in systemic sclerosis-related fibrosing alveolitis pathogenesis

BACKGROUND

Recent evidence has highlighted a potential role of interleukin 1β (IL-1β) in systemic sclerosis (SSc). NLRP1 provides a scaffold for the assembly of the inflammasome that promotes the processing and maturation of pro-IL-1β. In addition, NLRP1 variants were found to confer susceptibility to autoimmune disorders.

OBJECTIVE

/st> To study a possible association of the NLRP1 rs6502867, rs2670660 and rs8182352, rs12150220 and rs4790797 with SSc in the European Caucasian population.

METHODS

NLRP1 single nucleotide polymorphisms were genotyped in 3227 individuals comprising a discovery set (870 SSc patients and 962 controls) and a replication set including individuals from Germany (532 SSc patients and 324 controls) and Italy (527 SSc patients and 301 controls), all individuals being of European Caucasian origin.

RESULTS

Conditional analyses revealed a significant association for the NLRP1 rs8182352 variant with both anti-topoisomerase-positive and SSc-related fibrosing alveolitis (FA) subsets under an additive model: p=0.0042, OR 1.23 (95% CI 1.07 to 1.41) and p=0.0065 OR 1.19 (95% CI 1.05 to 1.36), respectively. Logistic regression analysis showed an additive effect of IRF5 rs2004640, STAT4 rs7574865 and NLRP1 rs8182352 risk alleles on SSc-related FA.

CONCLUSIONS

Our results establish NLRP1 as a new genetic susceptibility factor for SSc-related pulmonary fibrosis and anti-topoisomerase-positive SSc phenotypes. This provides new insights into the pathogenesis of SSc, underlining the potential role of innate immunity in particular in the FA-positive SSc subphenotype, which represents a severe subset of the disease.

Analysis of the influence of PTPN22 gene polymorphisms in systemic sclerosis

OBJECTIVE

Two functional single nucleotide polymorphisms (SNP) in the PTPN22 gene (rs24746601 and rs33996649) have been associated with autoimmunity. The aim of this study was to investigate the role of the R263Q SNP for the first time and to re-evaluate the role of the R620W SNP in the genetic predisposition to systemic sclerosis (SSc) susceptibility and clinical phenotypes.

METHODS

3422 SSc patients (2020 with limited cutaneous SSc and 1208 with diffuse cutaneous SSc) and 3638 healthy controls of Caucasian ancestry from an initial case--control set of Spain and seven additional independent replication cohorts were included in our study. Both rs33996649 and rs2476601 PTPN22 polymorphisms were genotyped by TaqMan allelic discrimination assay. A meta-analysis was performed to test the overall effect of these PTPN22 polymorphisms in SSc.

RESULTS

The meta-analysis revealed evidence of association of the rs2476601 T allele with SSc susceptibility (p(FDRcorrected)=0.03 pooled, OR 1.15, 95% CI 1.03 to 1.28). In addition, the rs2476601 T allele was significantly associated with anticentromere-positive status (p(FDRcorrected)=0.02 pooled, OR 1.22, 95% CI 1.05 to 1.42). Although the rs33996649 A allele was significantly associated with SSc in the Spanish population (p(FDRcorrected)=0.04, OR 0.58, 95% CI 0.36 to 0.92), this association was not confirmed in the meta-analysis (p=0.36 pooled, OR 0.89, 95% CI 0.72 to 1.1).

CONCLUSION

The study suggests that the PTPN22 R620W polymorphism influences SSc genetic susceptibility but the novel R263Q genetic variant does not. These data strengthen evidence that the R620W mutation is a common risk factor in autoimmune diseases.

Association of the TNFAIP3 rs5029939 variant with systemic sclerosis in the European Caucasian population

BACKGROUND

TNFAIP3 encodes the ubiquitin-modifying enzyme, a key regulator of inflammatory signalling pathways. Convincing associations between TNFAIP3 variants and autoimmune diseases have been reported.

OBJECTIVE

To investigate the association of TNFAIP3 polymorphisms with systemic sclerosis (SSc).

METHODS

Three single nucleotide polymorphisms (SNPs) in a set of 1018 patients with SSc and 1012 controls of French Caucasian origin were genotyped. Two intergenic SNPs, rs10499194 and rs6920220, and one located in TNFAIP3 intron 2, rs5029939, were selected. The TNFAIP3 rs5029939 found to be associated with SSc in this first set was then genotyped in a second set of 465 patients with SSc and 182 controls from Germany and 184 patients with SSc and 124 controls from Italy. Pooled odd ratios were calculated by Mantel-Haenszel meta-analysis.

RESULTS

The rs5029939 G allele was found to be significantly associated with SSc susceptibility (pooled OR=2.08 (95% CI 1.59 to 2.72); p=1.16×10⁻⁷), whereas the rs10499194 and rs6920220 variants displayed no association. Only one of the predicted haplotypes investigated in the French sample was significantly associated with SSc (p=8.91×10⁻⁸), and this haplotype was discriminating only in the presence of the rs5029939 risk allele, suggesting that this SNP tags the association signal. The strongest associations of rs5029939 with subphenotypes, having large magnitudes for complex genetic disorders, were observed for diffuse cutaneous SSc (pooled OR=2.71 (1.94 to 3.79), p=5.2×10⁻⁹), fibrosing alveolitis (pooled OR=2.26 (1.61 to 3.17), p=2.5×10⁻⁶) and pulmonary arterial hypertension (pooled OR=3.11 (1.86 to 5.17), p=1.3×10⁻⁵).

CONCLUSION

These results suggest that TNFAIP3 is a genetic susceptibility factor for SSc.

What are the new milestones in the pathogenesis of systemic sclerosis?

Systemic sclerosis (SSc) is a chronic inflammatory autoimmune disease involving the connective tissue of the skin and various internal organs. In recent years research on SSc has evolved to provide a better understanding of the interdependence of the three major systems involved--namely, the vascular system, the immune system and the connective tissue. Hypoxia is increasingly recognised as a decisive factor in modulating the inflammatory process in SSc, activating fibroblasts and changing their phenotype. In addition, several mediators synthesised by immune cells, including cytokines such as transforming growth factor beta (TGFbeta) and platelet-derived growth factor (PDGF), cooperate in inducing the activation of fibroblasts and their differentiation into myofibroblasts. Therefore, a variety of intracellular and extracellular strategies to inhibit the activity of TGFbeta and PDGF are currently receiving intense investigation. To further improve our therapeutic strategies for this paradigmatic fibrotic disease, an improved understanding of connective tissue remodelling as it takes place in the different stages of SSc will be imperative.

BANK1 functional variants are associated with susceptibility to diffuse systemic sclerosis in Caucasians

OBJECTIVE

To investigate the possible association of the BANK1 gene with genetic susceptibility to systemic sclerosis (SSc) and its subphenotypes.

METHODS

A large multicentre case-control association study including 2380 patients with SSc and 3270 healthy controls from six independent case-control sets of Caucasian ancestry (American, Spanish, Dutch, German, Swedish and Italian) was conducted. Three putative functional BANK1 polymorphisms (rs17266594 T/C, rs10516487 G/A, rs3733197 G/A) were selected as genetic markers and genotyped by Taqman 5 allelic discrimination assay.

RESULTS

A significant association of the rs10516487 G and rs17266594 T alleles with SSc susceptibility was observed (pooled OR=1.12, 95% CI 1.03 to 1.22; p=0.01 and pooled OR=1.14, 95% CI 1.05 to 1.25; p=0.003, respectively), whereas the rs3733197 genetic variant showed no statistically significant deviation. Stratification for cutaneous SSc phenotype showed that the BANK1 rs10516487 G, rs17266594 T and rs3733197 G alleles were strongly associated with susceptibility to diffuse SSc (dcSSc) (pooled OR=1.20, 95% CI 1.05 to 1.37, p=0.005; pooled OR=1.23, 95% CI 1.08 to 1.41, p=0.001; pooled OR=1.15, 95% CI 1.02 to 1.31, p=0.02, respectively). Similarly, stratification for specific SSc autoantibodies showed that the association of BANK1 rs10516487, rs17266594 and rs3733197 polymorphisms was restricted to the subgroup of patients carrying anti-topoisomerase I antibodies (pooled OR=1.20, 95% CI 1.02 to 1.41, p=0.03; pooled OR=1.24, 95% CI 1.05 to 1.46, p=0.01; pooled OR=1.26, 95% CI 1.07 to 1.47, p=0.004, respectively).

CONCLUSION

The results suggest that the BANK1 gene confers susceptibility to SSc in general, and specifically to the dcSSc and anti-topoisomerase I antibody subsets.

Skin sclerosis is only of limited value to identify SSc patients with severe manifestations--an analysis of a distinct patient subgroup of the German Systemic Sclerosis Network (DNSS) Register

OBJECTIVES

In SSc, diagnosis and classification is based mainly on skin sclerosis. Herein, we investigated in a large multicentre cohort, to what extent skin sclerosis reflects organ involvement and additional clinical symptoms.

METHODS

A total of 1200 SSc patients from the register of the German Systemic Sclerosis Network (DNSS), classified as either lcSSc or dcSSc, were analysed for their serological characteristics, clinical symptoms and organ manifestations in relation to skin involvement measured by the modified Rodnan skin score (mRSS).

RESULTS

SSc patients with different mRSS did not differ significantly in their disease duration and in most of the clinical symptoms. They showed a similar distribution of most organ manifestations such as pulmonary arterial hypertension as well as cardiac, renal and nervous system involvement. More severe skin thickening was found to be associated with pulmonary fibrosis and gastrointestinal symptoms, as well as with digital ulcers and musculoskeletal involvement.

CONCLUSIONS

In patients with SSc, potentially life-threatening complications and clinical symptoms with high impact on the quality of life occur independently from the extent of skin sclerosis. The diagnosis in SSc patients with a low mRSS could be missed or they could be insufficiently treated.

Comparison of patients with and without digital ulcers in systemic sclerosis: detection of possible risk factors

BACKGROUND

Digital ulcers (DU) are a major complication in the course of systemic sclerosis (SSc). In recent years, efficacious, but expensive therapies (e.g. iloprost, sildenafil, bosentan) have been shown to improve healing or to reduce the recurrence of DU. For optimal management it would be useful to identify the risk factors for DU. Such statistical analyses have been rare because they require a high number of patients.

OBJECTIVES

To identify potential risk factors for DU in patients with SSc.

METHODS

We used the registry of the German Network for Systemic Scleroderma and evaluated the data of 1881 patients included by August 2007. We assessed potential risk factors for DU by comparing patients with (24.1%) and without active DU at time of entry (75.9%).

RESULTS

Multivariate analysis revealed that male sex, presence of pulmonary arterial hypertension (PAH), involvement of the oesophagus, diffuse skin sclerosis (only when PAH was present), anti-Scl70 antibodies, young age at onset of Raynaud's phenomenon (RP), and elevated erythrocyte sedimentation rate (ESR) significantly impacted on the appearance of DU. Certain combinations increased the patients' probability of presenting with DU, with the highest probability (88%) for male patients with early onset of RP, ESR>30 mm h(-1), anti-Scl70 antibodies and PAH. Patients with DU developed RP, skin sclerosis and organ involvement approximately 2-3 years earlier than patients without DU.

CONCLUSIONS

The results reveal possible risk factors for the occurrence of DU in SSc. As DU are prone to local complications, prophylactic vasoactive treatment for patients presenting with these factors may be justified.

The registry of the German Network for Systemic Scleroderma: frequency of disease subsets and patterns of organ involvement

Objective. Systemic sclerosis (SSc) is a rare, heterogeneous disease, which affects different organs and therefore requires interdisciplinary diagnostic and therapeutic management. To improve the detection and follow-up of patients presenting with different disease manifestations, an interdisciplinary registry was founded with contributions from different subspecialties involved in the care of patients with SSc.

Methods. A questionnaire was developed to collect a core set of clinical data to determine the current disease status. Patients were grouped into five descriptive disease subsets, i.e. lcSSc, dcSSc, SSc sine scleroderma, overlap-syndrome and UCTD with scleroderma features.

Results. Of the 1483 patients, 45.5% of patients had lcSSc and 32.7% dcSSc. Overlap syndrome was diagnosed in 10.9% of patients, while 8.8% had an undifferentiated form. SSc sine scleroderma was present in 1.5% of patients. Organ involvement was markedly different between subsets; pulmonary fibrosis for instance was significantly more frequent in dcSSc (56.1%) than in overlap syndrome (30.6%) or lcSSc (20.8%). Pulmonary hypertension was more common in dcSSc (18.5%) compared with lcSSc (14.9%), overlap syndrome (8.2%) and undifferentiated disease (4.1%). Musculoskeletal involvement was typical for overlap syndromes (67.6%). A family history of rheumatic disease was reported in 17.2% of patients and was associated with early disease onset (P < 0.005).

Conclusion. In this nationwide register, a descriptive classification of patients with disease manifestations characteristic of SSc in five groups allows to include a broader spectrum of patients with features of SSc.

[The German Network for Systemic Scleroderma]

Systemic scleroderma (SSc) is a rare, heterogenous, multisystem disease affecting different organ systems and therefore requires interdisciplinary management and patient care. The German Network for Systemic Scleroderma, funded by the country's Federal Ministry of Education and Research, was established 3 years ago and comprises dermatologists, rheumatologists, pulmonologists, and nephrologists from more than 40 medical centers. The registry contains data of more than 1800 patients. Analysis of the continually growing body of data will form the basis for the development of standardized recommendations for diagnosis and treatment of SSc.