Elsevier

Journal of Autoimmunity

Volume 60, June 2015, Pages 80-85
Journal of Autoimmunity

Primary Sjögren's syndrome and occupational risk factors: A case–control study

https://doi.org/10.1016/j.jaut.2015.04.004Get rights and content

Highlights

  • A case–control study was performed to evaluate associations between primary Sjögren's syndrome (pSS) and occupational risk factors.

  • One hundred seventy five cases and 350 age and gender matched control were included.

  • Significant associations with pSS were observed for white spirit or chlorinated or aromatic solvents exposure.

  • No significant association withpSS was observed for silica.

  • This work suggests the influence of environment and occupational risk factors in the occurrence of pSS.

Abstract

Objectives

A case–control study was carried out to investigate the relation between primary Sjögren's syndrome (pSS) and occupational exposure.

Methods

One hundred seventy five cases of pSS followed up into the internal medicine departments of three French university hospitals from 2010 to 2013 were included. For each case, two age and gender matched controls were selected during the same period in the same departments. Occupational exposure was assessed retrospectively by industrial hygienists and occupational practitioners. Exposure to occupational factors such as organic solvents or silica was investigated using semiquantitative estimates of exposure. An exposure score was calculated for each subject based on probability, intensity, daily frequency, and duration of exposure for each period of employment. The final cumulative exposure score was obtained, taking into account all periods of employment.

Results

Significant associations with pSS were observed for dichloromethane (OR 9.28, 95%CI 2.60–33.03), perchlorethylene (OR 2.64, 95%CI 1.20–5.77) chlorinated solvents (OR 2.95, 95%CI 1.77–4.93), benzene (OR 3.30, 95%CI 1.07–10.26), toluene (OR 4.18 95%CI 1.41–12.43), white spirit (OR 3.60, 95%CI 1.39–9.33), aromatic solvents (OR 3.03, 95%CI 1.41–6.50) and any types of solvents (OR 2.76, 95%CI 1.70–4.47). Risk of pSS was significantly associated with a high cumulative exposure score of occupational exposure to toluene (OR 4.69, 95%CI 1.42–15.45), white spirit (OR 3.30, 95%CI 1.07–10.26), aromatic solvents (OR 2.50, 95%CI 1.06–5.91) and any types of solvents (OR 2.25, 95%CI 1.20–4.22).

Conclusion

This work suggests the influence of occupational risk factors in the occurrence of pSS.

Introduction

Sjögren's syndrome (pSS) is a systemic disease that was originally described in 1956 by Bloch et al. [1] Its prevalence is of 0–5% with a female preponderance (9 female to one male) [2], [3]. It is an autoimmune epithelitis characterized by eye and mouth dryness and lymphocytic infiltration of the salivary glands [3], [4], [5]. Apart from dryness, clinical presentation generally comprises asthenia and arthralgia [6], [7]. Moreover, the disease can extend beyond the exocrine glands and systemic manifestations including vasculitis, lung, renal or neurological involvement can potentially occur. In addition patients with pSS have an increased risk of lymphoma [8], [9]. As for other autoimmune diseases, it is associated with specific genetic background, impaired immune response and environmental factors [10]. Such factors are believed to trigger an innate immune response which leads to an activation of glandular cells and an alteration of glandular vascular endothelium [3], [11]. These phenomenon are followed by an activation of B and T lymphocytes within the glands which leads to cell destruction, cytokine production such as type I and II interferon [12], and autoantibodies secretion [3], [10]. Impaired salivary and lachrymal secretions are the consequence of the glandular dysfunction. To date, only a few environmental factors have been identified in pSS. Only weak associations with viruses have been reported and less than ten cases of patients with pSS exposed to silica were reported [13], [14], [15]. Occupational exposure to silica is known to be associated with autoimmune diseases such as systemic sclerosis and systemic lupus erythematosus [16], [17]. Therefore we hypothesized that occupational risks factors are associated with pSS. Herein we report a multicentric French case–control study that investigated the relationship between pSS and occupational exposure.

Section snippets

Patients

One hundred seventy five patients with pSS followed up in departments of Internal Medicine of the University Hospitals of Tours (France), Rouen (France), and Angers (France), from 2010 to 2013 were included in the study. pSS was defined according to the American-European Consensus Group (AECG) criteria [18].

Two age (±5 years) and gender matched controls were selected for each case. Controls were selected during the same period of time in the same departments. Subjects with connective tissue

Results

Between January 2010 and December 2013, 175 pSS patients and 350 matched controls were included in the study. Table 1 shows socioeconomic data of cases and controls. There was no difference between cases and controls for smoking habit and socio-economic levels and socio-professional categories were similar.

One hundred sixty eight patients (96%) reported ocular and oral symptoms. One hundred fifty patients (85.7%) had ocular signs and 50 patients (28.6%) had salivary gland involvement. Anti-SSA

Discussion

This case–control study shows that occupational exposure to certain organic solvents (chlorinated, aromatic) is associated with an increased risk of pSS. Our work is the first case–control study to evaluate occupational exposure in pSS. As our population was homogeneous because we only included patients with pSS and excluded patients with other autoimmune disease, we estimate that our results are highly specific for pSS.

As for other autoimmune diseases, environmental factors are believed to

Conclusion

In conclusion, this case–control study suggests the influence of occupational exposure in the development of pSS, especially exposure to white spirit or chlorinated or aromatic solvents, whereas exposure to crystalline silica is not associated with pSS. Further studies are needed to confirm a causative role in the development of the disease.

Competing interests

None.

Funding

None.

Contributorship statement

All authors have contributed to the planning, the conduct, and the reporting of the work described in the study.

Acknowledgments

The authors are grateful to Mrs. Penelope Hodges for her precious help all along the study and to Mr. Benjamin Schwartz for his precious comments on the manuscript.

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