Exploring lifetime occupational exposure and SLE flare: a patient-focussed pilot study

Our plain-English summary of Exploring lifetime occupational exposure and SLE flare: a patient-focussed pilot study, by M.L. Squance, M. Guest, G. Reeves, et al (Lupus Science & Medicine, 2014).

The study

• Authors: M.L. Squance, M. Guest, G. Reeves, J. Attia, H. Bridgman
• Journal: Lupus Science & Medicine
• Published: 2014;1(1):e000023
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Introduction: Environmental effectors, such as ultraviolet radiation exposure, infection and stress, have been established as having a role in exacerbating lupus symptoms. However, unpredictable patterns of flare events still remain a mystery. Occupational effectors have also been suggested as having a contributing role; however, they are not widely researched. In this paper we report a pilot study designed to generate focus areas for future research regarding occupational exposures and systemic lupus erythematosus (SLE).

Methods: The study explored potential links between exposures and the occurrence of patient-reported flare events in 80 Australian women with SLE (American College of Rheumatology (ACR) criteria classified). Specifically, the study assessed the hypothesis that occupational exposure is associated with significant changes in the likelihood of lupus flares. Lifetime employment history was analysed with the Finnish Job Exposure Matrix (FINJEM), 40 different semiquantified exposure class estimates for a wide number of occupations based on probability of exposure (p≥5%=exposed) were analysed with the construction of negative binomial regression models to test relationships between occupational agents and flare days. A backward stepwise elimination was used to generate a parsimonious model.

Results: Significant associations were noted for exposure classes of manual handling burden, (p=0.02, incidence rate ratio (IRR) 1.01), Iron (p=0.00, IRR 1.37), wood dust (p=0.00, IRR 3.34) and asbestos (p=0.03, IRR 2.48).

Conclusion: Exposure assessment results indicated that occupations, such as nursing, with a high manual handling burden, posed increased risk to patients with SLE, however, the greatest risk was associated with wood dust and iron exposure with teachers and specialist labourers.

In plain English

This pilot study retrospectively analysed 80 Australian women with systemic lupus erythematosus (SLE) from New South Wales clinics. The outcome was lupus flares, not asbestos-related disease. Lifetime job histories were converted into likely exposures using the Finnish Job Exposure Matrix, based on job titles. Researchers calculated flare days from each woman's reported number and length of flares over the previous 12 months. Statistically significant associations with more flare days were found for manual handling (incidence rate ratio 1.01, 95% CI 1.00 to 1.02), iron (1.37, 1.2 to 1.5), wood dust (3.34, 2.1 to 5.3) and asbestos. The 12 asbestos-exposed women (15%) had an incidence rate ratio of 2.48 (95% CI 1.2 to 5.4). Of these, seven (58.3%) had worked as warehouse storepersons or shelf stackers. Solvents, heavy metals and pesticides showed no increased risk. The authors concluded the greatest risk was associated with wood dust and iron among teachers and specialist labourers. They stated results were not adjusted for multiple comparisons and must be seen as hypothesis generating. They noted widespread past asbestos use in Australia would indicate more widespread exposure.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Retrospective analysis of a patient cohort (pilot study), using questionnaires, a clinical interview, self-reported flare history and a job exposure matrix, analysed with negative binomial regression
• Who was studied: 80 women aged 18 to 80 with SLE (American College of Rheumatology criteria, diagnosed at least 2 years), from the Autoimmune Resource and Research Centre and Immunology clinics in New South Wales, Australia. Mean age was 48 and 97.5% were Caucasian. Men were excluded because few responded. Study dates are not stated.
• Exposure: Lifetime occupational exposures estimated from job titles with the Finnish Job Exposure Matrix (FINJEM), covering chemical, physical and ergonomic agents, including asbestos. Asbestos fiber type is not specified. A probability of exposure of 5% or more counted as exposed.
• Main results:
  • Flare days were not reported directly by the women: the researchers calculated a total from each woman's self-reported length of flare events and estimated number of flares in the preceding 12 months.
  • Asbestos, dichotomised (exposed vs not): the 12 exposed participants (15%) had an incidence rate ratio of 2.48 for flare days (95% CI 1.2 to 5.4, p=0.03). As a semiquantified exposure, asbestos had an incidence rate ratio of 1.08 (95% CI 1.01 to 1.2, p=0.03).
  • Of the asbestos-exposed participants, 7 (58.3%) had nominated jobs as warehouse storepersons or shelf stackers. The table lists the asbestos-exposed jobs as fitter-assemblers, electricians, carpenters, painters, manufacturing and warehouseman (7).
  • Iron exposure (11 participants, 13.8%): incidence rate ratio 1.37 (95% CI 1.2 to 1.5, p printed as 0.00). Wood dust (12 participants, 15%): incidence rate ratio 3.34 (95% CI 2.1 to 5.3, p printed as 0.00). Both associations were driven mainly by 11 participants in teaching occupations.
  • The authors reported that the teachers' job records showed no individual documented sources of iron or wood dust.
  • Manual handling burden (69 participants, 86.3%): incidence rate ratio 1.01 (95% CI 1.00 to 1.02, p=0.02).
  • Solvents, aromatic hydrocarbons, heavy metals, pesticides, ultraviolet radiation and hot environments did not show increased risk.
• The authors' conclusion: The authors concluded that occupations such as nursing, with a high manual handling burden, posed increased risk to patients with SLE. They concluded that the greatest risk was associated with wood dust and iron exposure among teachers and specialist labourers. They called for replication in other populations.
• Limitations the authors state:
  • FINJEM gives 40 exposure classes, so false positives from multiple comparisons are possible. There was no adjustment for this, and the authors said the results must be seen as hypothesis generating.
  • Exposures were estimates based on job titles, without weighting for individual tasks or work environment, so exposure classification may be wrong.
  • Flares were self-reported from the patient perspective, without traditional disease activity tools. Individual symptoms could not be matched to each reported flare event.
  • Standard clinical disease activity tools were not used.
  • The cohort was all female and almost entirely Caucasian, which limits how far the findings apply to other populations.
  • Because asbestos was used so widely in Australia, exposure was likely more widespread than the job-based estimates captured, which the authors said makes the asbestos finding difficult to interpret.

Topics

Medical terms in this study, explained in our Lexicon: Occupational Exposure, Incidence.

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