Melanoma Diagnostic Processes and the Occurrence of Advanced Disease in Ontario
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Authors
Mavor, Meaghan
Date
Type
thesis
Language
eng
Keyword
Epidemiology , Melanoma , Diagnostic delay , Diagnostic interval , Diagnostic pathways , Health services research
Alternative Title
Abstract
Background: Reasons for the occurrence of advanced melanoma and an understanding of melanoma diagnostic processes and their relationship with advanced disease is understudied.
Methods: This thesis examined the melanoma diagnostic process in Ontario using abstracted pathology reports and administrative data held at ICES. Objective 1 described the occurrence of advanced melanoma using abstracted pathology reports on a 65% random sample of people diagnosed with melanoma in Ontario from 2007–2012. We used modified Poisson regression to identify factors associated with advanced melanoma, stratifying by ulceration, which is a marker of clinical appearance and prognosis. Objectives 2–4 used ICES data. Objective 2 described the melanoma diagnostic interval (DI) for all Ontario melanoma patients diagnosed from 2007–2019. We used quantile regression to evaluate the association between patient-, disease-, and system-level factors and the length of the DI and primary care (PCI) and specialist care (SCI) subintervals. Objective 3 used latent class cluster analysis to group patients who experienced similar diagnostic processes. Objective 4 used quantile regression with restricted cubic splines to examine the relationship between melanoma thickness and DI length, stratified by ulceration.
Results: Advanced melanoma was diagnosed in 26% of patients, and age, sex, socioeconomic status, and health region were associated with an increased risk of advanced disease. Ulceration attenuated these effects. Median DI was 36 days (Interquartile range [IQR]: 8–85 days), PCI was 22 days (IQR: 6–54 days) and SCI was 6 days (IQR: 1–42 days). Different factors were associated with the lengths of the DI, PCI, and SCI. We identified four diagnostic pathways: “primary care only”, “referred to specialist for immediate action”, “multiple visits and procedures in SCI”, and “specialist care only”. The distribution of patient-, disease-, and system-level factors, along with the lengths of the DI, PCI, and SCI varied across pathways. Finally, we found a complex relationship between thickness and DI duration, which differed by ulceration.
Conclusions: We found independent risk factors for advanced melanoma in Ontario. This research identified variation in the melanoma diagnostic process within, and across, Ontario. We did not find a significant association between a longer DI and thicker melanomas.
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ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.