Background: Pulmonary blastomycosis is a lung infection caused by thermally dimorphic fungi Blastomyces spp. It is endemic to the Great Lakes area, especially Northwestern Ontario. Previous studies were mostly from the United States, which may not be able to represent the regional demographic where we observed several cases of previously healthy young patients experiencing ICU admission.
Purpose: We aimed to describe the epidemiology of ICU admission (severe disease) rates of pulmonary blastomycosis and further to identify risk factors associated with severe pulmonary blastomycosis in the Northwestern Ontario.
Methods: A retrospective cohort study was used to identify risk factors associated with severe disease, including ICU admission rates of blastomycosis in Thunder Bay from January 2015 to December 2024. Relative Risk with multivariate analysis and forest plots was calculated according to demographic information such as gender, age ≥ 65, ethnicity, time from onset to diagnosis, comorbidities (i.e., Prednisone ≥ 20 mg per day for more than four weeks, transplantation, active cancer (receiving tx or metastasis), hematologic malignancy, HIV, end-stage renal or hepatic disease, pregnancy, receiving biologics, intravenous drug use, Diabetes, COPD, asthma, cystic fibrosis), and multiple lobar disease. Data collection from 2015 to 2024 was completed at Thunder Bay Regional Health Sciences Centre, a tertiary hospital, and is ongoing from Sioux lookout Hospital and Kenora Hospital.
Results: Preliminary data on the Thunder Bay site included 105 hospitalized patients, of whom 62 (59%) required ICU admission. In multivariable analysis, the presence of multi-lobar disease on initial imaging on presentation was the strongest independent predictor of ICU admission (Relative Risk [RR] 2.72; 95% CI 1.18, 6.27; p = 0.019). Other analyzed variables, including age, male sex, comorbidities, and time from symptom onset to diagnosis, were not significantly associated with an increased risk for ICU admission.
Conclusions: Multi-lobar disease on presentation is the strongest independent predictor of severe pulmonary blastomycosis in the Thunder Bay cohort. On the other hand, no significant association was found between time from symptom onset to diagnosis and ICU admission. Further data collection and analysis may elucidate other risk factors of pulmonary blastomycosis associated with ICU admission in Northern Ontario.
Author Contributions
Conceptualization, M.S. and B.B.; methodology, M.S.; software, M.S.; validation, M.S., B.B. and Y.S.; formal analysis, M.S.; data curation, M.S.; writing—original draft preparation, M.S.; writing—review and editing, M.S., B.B. and Y.S.; supervision, B.B.; project administration, M.S., B.B. and Y.S.; funding acquisition, M.S. and Y.S. All authors have read and agreed to the published version of the manuscript.
Funding
This research was funded by Seed Funding TBRHSC, grant number RP-1091.
Institutional Review Board Statement
The study was conducted in accordance with the Declaration of Helsinki, and approved by the Institutional Review Board of Thunder Bay Regional Health Sciences Centre (protocol code 100291, approved on 8 November 2024).
Informed Consent Statement
Not applicable.
Data Availability Statement
The datasets presented in this article are not readily available because the data are part of an ongoing study. Requests to access the datasets should be directed to Minghan Shi.
Acknowledgments
We would like to thank Alexandra Stubbs and Kaylyn Dawydenko for data curation, Mansoureh Ebrahimi for grant application and management, and Sacha Dubois for statistical analysis support.
Conflicts of Interest
The authors declare no conflicts of interest.
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