Understanding environmental risk factors associated with vasculitis in United Kingdom

Havyarimana, Enock (2023) Understanding environmental risk factors associated with vasculitis in United Kingdom. PhD thesis, University of Glasgow.

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Systemic vasculitis constitutes a range of multi-system disorders that affect small, to medium, and large blood vessels. These disorders affect 1 to 34 cases per million population each year with ANCA-Associated vasculitis (AAV) and Giant cell arteritis (GCA) being the most prevalent vasculitis in people over the age 50. The aetiology is still unknown. Recent evidence has suggested that occupation airborne exposures and serious infections may be an important risk factor for AAV. The extent to which this is true at population level is not yet clear.

The primary objectives of this thesis were (i) to investigate the long-term impact of outdoor air pollution on the onset of vasculitis, (ii) interrogate the role of geography in mediating the relationship between air pollution and vasculitis (iii) assess the temporal and seasonal variation of vasculitis onset and the possible links with environmental exposures. The method used in this thesis encompassed a systematised review, an environmental-wide association study (EWAS) approach using cross-sectional data from UK Biobank and the Scottish Morbidity Record. A series of multivariable analyses adjusted for important confounders were used to quantify the relationship between air pollution and vasculitis.

Findings from the systematised review indicated that the effects of air pollution on vasculitis are variable depending on geography. It also showed that occupation airborne exposures and farming were associated 2-fold risk of vasculitis, especially for AAV. Results from UK Biobank and SMR01 suggests that long-term exposure to sulphur dioxide (SO2) is associated with 6.4% and 6.9% increased odds of developing vasculitis, particularly AAV. Particulate matter (PM10 and PM2.5) was uniquely associated with GCA. Importantly, geography was seen to play an important role in vasculitis. Individuals from rural areas had 18% and 16% higher risk of vasculitis compared with individual from urban areas in UK Biobank and SMR01.

The temporal and seasonal analyses of AAV indicated that there are two major peaks in the incidence of AAV in Scotland. The first was seen between 1996-2000 after the introduction of antineutrophil cytoplasmic antibodies (ANCA) testing in clinical settings in the early 1990s. The second peak was between 2017-2018 (2nd peak) and could potentially be linked with environmental agent. Overall, there was no seasonal variation in the incidence of AAV.

This thesis introduces important novel and validated results that show that outdoor air pollution may be an important risk factor of vasculitis. There is scope to build on this work in other international cohorts through data linkage of routine health data and environmental data by means EWAS study design.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Supported by funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 813545.
Subjects: Q Science > QR Microbiology
Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Infection & Immunity
Supervisor's Name: Basu, Professor Neil, Cullen, Dr. Breda and Lee, Professor Duncan
Date of Award: 2023
Depositing User: Theses Team
Unique ID: glathesis:2023-83846
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 24 Oct 2023 12:45
Last Modified: 24 Oct 2023 12:46
Thesis DOI: 10.5525/gla.thesis.83846
URI: https://theses.gla.ac.uk/id/eprint/83846
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