Independent association between occupational exposure and decline of forced vital capacity in systemic sclerosis (SSc): a multicenter recruitment retrospective cohort study

Job-exposure matrix (JEM) validity on crystalline silica among systemic sclerosis patients

BACKGROUND

Systemic sclerosis (SSc) is the connective tissue disease with the highest individual mortality. Crystalline silica is known to be an occupational risk factor for SSc. To assess past crystalline silica exposure, we aimed to study the validity of a job exposure matrix (JEM) to assess occupational exposure to crystalline silica compared to specific occupational interviews in two populations of SSc patients.

AIMS

To demonstrate the reliability of JEM for the assessment of occupational exposure to hazards such as silica, in severe rare disorders like SSc.

METHODS

Patients from two university hospital centres underwent standardized assessment of occupational silica exposure and collected job histories through face-to-face interviews. A JEM from the French program Matgéné was used to assess silica exposure and compared to the standardized interview results. Standard metrics were computed for evaluate the accuracy of JEM.

RESULTS

67 participants from Rennes, and 119 from Tours were included, with respectively 10.5% and 18.0% of patients with silica exposure based on the results of the interview. The JEM with 50% probability cut-off had a good performance when compared with the classic assessment method. A cumulative exposure index from JEM over 250 had an area under the curve between 0.76 and 0.79 and also a very high positive likelihood ratio (17.14 and 10.29).

CONCLUSIONS

Despite limitations inherent to JEMs and associated validation methods, the JEM used in this setting provided accurate results to assess occupational exposure to crystalline silica for clinical purposes such as in SSc patients, especially to detect positive cases.

Occupational dust and chemical exposures and the development of autoimmune rheumatic diseases

Although the association between certain occupational exposures and the development of autoimmune rheumatic disease was first described over a century ago, this association has only become more widely recognized in the past 10 years because of the use of high-silica-content engineered stone in construction and home renovation. There is now a substantial and growing body of evidence that occupational dust and chemical exposure, be it through mining, stonemasonry, building or other trades, increases the risk of various systemic autoimmune rheumatic diseases (SARDs) including rheumatoid arthritis and systemic sclerosis. Although the pathogenic mechanisms of silica-induced autoimmunity are not fully elucidated, it is thought that alveolar macrophage ingestion of silica and the ensuing phagosomal damage is an initiating event that ultimately leads to production of autoantibodies and immune-mediated tissue injury. The purportedly causal association between occupational exposure to chemicals, such as organic solvents, and an increased risk of SARDs is less frequently recognized compared with silica dust, and its immunopathogenesis is less well understood. An appreciation of the importance of occupational dust and chemical exposures in the development of SARDs has implications for workplace health and safety regulations and offers a unique opportunity to better understand autoimmune disease pathogenesis and implement preventative strategies.

Occupational quantitative exposure to crystalline silica, solvents and pesticides and risk of clinical forms of systemic sclerosis

OBJECTIVES

To estimate the association between SSc clinical phenotypes and quantitative occupational exposure to crystalline silica, chlorinated solvents, trichloroethylene and pesticides using job-exposure matrices.

METHODS

In the VISS-EXPOSITION transversal study, data on declarative occupational exposure to crystalline silica, solvents and pesticides were retrieved. In parallel, the lifetime occupational history was evaluated using a questionnaire and cursus laboris for SSc patients followed at Bordeaux University Hospital (France). Using job-exposure matrices, we assessed patients' occupational exposure in relation to relevant clinical phenotypic forms of the disease.

RESULTS

Toxic exposure to crystalline silica and pesticides is underestimated by patients. Non-biased job-exposure matrices retrieved more exposed patients than the declarative assessment (10.1% of patients by job-exposure matrices vs 6.3% by declaration for crystalline silica and 25.9% vs 12.2% for pesticides). Patients overestimate their solvent exposure (7.9% for chlorinated solvents and 4.8% for trichlorethylene assessed by job-exposure matrices and 24.4% declarative exposure to solvents at large). Clinical form evaluation revealed a non-significant trend toward an increased risk of crystalline silica occupational exposure in the pulmonary fibrotic group of SSc patients [odds ratio (OR) 3.12 (95% CI 0.80, 12.15)]. We also observed a non-significant trend toward an elevated OR ([2.89 (95% CI 0.93, 8.95)] for chlorinated solvent occupational exposure and the vascular phenotype of SSc. Of note, pesticide occupational exposure evaluation represents one of the largest to date in SSc patients.

CONCLUSION

This study emphasizes that many exposed SSc patients are unaware of their occupational exposure. Job-exposure matrices allow better exposure screening for SSc secondary prevention and occupational exposure compensation.

CLINICAL TRIAL REGISTRATION

clinicaltrials.gov (https://www.clinicaltrials.gov), NCT03543956.

Interstitial Lung Disease Associated with Systemic Sclerosis

Systemic sclerosis (SSc) is a rare autoimmune disease characterized by a tripod combining vasculopathy, fibrosis, and immune-mediated inflammatory processes. The prevalence of interstitial lung disease (ILD) in SSc varies according to the methods used to detect it, ranging from 25 to 95%. The fibrotic and vascular pulmonary manifestations of SSc, particularly ILD, are the main causes of morbidity and mortality, contributing to 35% of deaths. Although early trials were conducted with cyclophosphamide, more recent randomized controlled trials have been performed to assess the efficacy and tolerability of several medications, mostly mycophenolate, rituximab, tocilizumab, and nintedanib. Although many uncertainties remain, expert consensus is emerging to optimize the therapeutic management and to provide clinicians with evidence-based clinical practice guidelines for patients with SSc-ILD. This article provides an overview, in the light of the latest advances, of the available evidence for the diagnosis and management of SSc-ILD.

High Prevalence of the Lung Ultrasound Interstitial Syndrome in Systemic Sclerosis Patients with Normal HRCT and Lung Function-A Pilot Study

Objective: High-resolution computed tomography (HRCT) may lack sensitivity for the early detection of interstitial lung disease associated with systemic sclerosis (SSc-ILD). Lung ultrasound is an emerging technique for the diagnosis of SSc-ILD. This cross-sectional study aimed to describe the prevalence of ultrasound interstitial syndrome in SSc patients with normal HRCT and pulmonary function tests (PFT). Methods: Thirty SSc patients with normal HRCT, FVC > 80% predicted and DLCO > 70% predicted were included. Echocardiography and PFT including impulse oscillometry and cardiopulmonary exercise testing were performed. Lung ultrasound was analyzed by two blinded operators. Patients were classified into two groups, according to the presence or absence of ultrasound interstitial syndrome, defined as the sum of B-lines in all thoracic areas ≥10 and/or pleural line thickness >3 mm on at least one thoracic area and/or a pleural line irregularity score >16%. Results: Ultrasound interstitial syndrome was present in 12 patients (40%). Inter-reader agreement for the diagnosis of ultrasound interstitial syndrome defined by the Kappa coefficient was 0.93 (95%CI 0.79-1.00). Patients with ultrasound interstitial syndrome were younger (37 years vs. 53 years, p = 0.009), more often had pitting scars (n = 7/12 vs. 3/18, p = 0.045) and had lower FVC (102 vs. 110% pred, p = 0.009), TLC (114 vs. 122% pred, p = 0.042) and low-frequency respiratory system reactance (Xrs5 Z-score 0.16 vs. 1.02, p = 0.018), while pulmonary gas exchange was similar. Conclusions: Ultrasound interstitial syndrome was detected in 12/30 SSc patients with normal HRCT and PFT. Patients with ultrasound interstitial syndrome had differences in lung function consistent with reduced respiratory compliance, suggesting minimal and/or early suspected SSc-ILD.

Contemporary Concise Review 2022: Interstitial lung disease

Novel genetic associations for idiopathic pulmonary fibrosis (IPF) risk have been identified. Common genetic variants associated with IPF are also associated with chronic hypersensitivity pneumonitis. The characterization of underlying mechanisms, such as pathways involved in myofibroblast differentiation, may reveal targets for future treatments. Newly identified circulating biomarkers are associated with disease progression and mortality. Deep learning and machine learning may increase accuracy in the interpretation of CT scans. Novel treatments have shown benefit in phase 2 clinical trials. Hospitalization with COVID-19 is associated with residual lung abnormalities in a substantial number of patients. Inequalities exist in delivering and accessing interstitial lung disease specialist care.

Sex differences in clinical outcomes and biological profiles in systemic sclerosis-associated interstitial lung disease: a post-hoc analysis of two randomised controlled trials

Background

Observational studies have shown that men with systemic sclerosis have an increased risk of interstitial lung disease (ILD) and mortality compared with women. However, previous studies have not controlled for treatment effect or evaluated the biological mechanism or mechanisms underlying this sex difference. We aimed to compare ILD progression and long-term morbidity and mortality outcomes in male and female participants of two randomised controlled trials for systemic sclerosis-associated ILD.

Methods

For this post-hoc analysis, data from all participants in the Scleroderma Lung Study (SLS) I and SLS II were analysed. The primary objective was to explore the effect of sex on the course of the percentage predicted forced vital capacity (FVC) during and after active treatment over the 24-month study periods. In SLS I, 158 participants (111 women, 47 men) were randomly assigned to receive oral cyclophosphamide (cyclophosphamide; ≤2 mg/kg daily) or placebo; in SLS II, 142 participants (105 women, 37 men) were randomly assigned to receive oral mycophenolate mofetil (1500 mg twice daily) or oral cyclophosphamide (≤2 mg/kg daily). Sex (ie, male or female) was self-reported in both studies by the participants. Changes in radiographic fibrosis and time to death and respiratory failure were secondary outcomes of the present analysis. Baseline levels of biomarkers implicated in the pathobiology of systemic sclerosis-associated ILD were measured in bronchoalveolar lavage fluid in SLS I.

Findings

In the SLS I placebo group, the rate of decline in percentage predicted FVC from 3 months to 12 months was greater in men than in women, but the difference was not significant (estimated effect -0·29 [95% CI -0·67 to 0·10]; p=0·14). In SLS II, the rate of decline in percentage predicted FVC from 3 months to 12 months was significantly worse in men treated with either cyclophosphamide (estimated effect -0·72; [95% CI -1·14 to -0·31]; p=0·00060) or mycophenolate mofetil (estimated effect -0·34 [-0·58 to -0·10]; p=0·0051) than in women. A greater proportion of men had a decline in percentage predicted FVC of 10% or greater compared with women for the pooled active treatment groups from SLS I and SLS II and the placebo group of SLS I. Men had worse radiographic outcomes at 2 years than women in SLS II, even after adjusting for baseline disease severity and treatment arm assignment. Long-term survival was worse in men in SLS I (log-rank test p=0·080) and SLS II (log-rank test p=0·030). In SLS II, male sex was independently associated with increased mortality (hazard ratio 2·42 [95% CI 1·16 to 5·04]; p=0·018). In bronchoalveolar lavage fluid, men had increased concentrations of pro-fibrotic mediators (eg, matrix metalloproteinase-13 and tissue inhibitor of metallopeptidase 1), whereas women had increased pro-inflammatory mediators (eg, interleukin [IL]-12, IL-7, and granulocyte-colony stimulating factor).

Interpretation

In two randomised controlled trials, men with systemic sclerosis-associated ILD had a less favourable course of ILD both with and without active treatment, as well as worse long-term survival. Sex differences in pro-fibrotic or inflammatory mediators of disease might account for these differences and warrant future study.

Funding

US National Institutes of Health; US National Heart, Lung, and Blood Institute; US National Institute of Arthritis and Musculoskeletal and Skin Diseases; Bristol Myers Squibb; and Hoffmann-LaRoche.