Does Location Matter? a Population-Based Analysis of Survival after Blood and Marrow Transplantation in Rural Versus Urban Manitobans
Authors: Paulson Kristjan , Lambert Pascal , Szwajcer David , Nowatzki Janet , Bredeson Christopher , Richardson Erin , Rubinger Morel , Seftel Matthew D. 
Published: April 2020

Abstract
Objective: Specialized health services such as blood and marrow transplantation (BMT) are based in large urban centres. A previous study suggested that rural patients may have inferior outcomes after BMT. We hypothesized that rural Manitobans have reduced access to BMT and higher mortality rates after BMT than urban Manitobans.
Methods: This population-based historical cohort study was based in Manitoba, Canada, a province of 1.2 million people that is served by a single, publicly funded BMT program. We utilized data from both the Manitoba BMT Program and the provincial Cancer Registry. Consecutive adult Manitobans who underwent BMT at Health Sciences Centre, Winnipeg between 01/1990 and 12/2006 were assessed. We analyzed distance of residence from the BMT centre, disease and BMT characteristics, and calculated overall survival (OS). Secondly, to measure access to BMT, we evaluated all patients with newly diagnosed Hodgkin Lymphoma (HL) during this same period. We compared the proportion of rural and urban Manitobans diagnosed with HL to those who received a BMT for HL.
Results: 464 Manitobans underwent BMT (179 rural, 285 urban). Rural Manitobans had inferior 5 year OS (45% vs. 37%, p&lt;0.05). A gradient was apparent; patients who lived &lt; 20 km from the BMT centre had superior 5 year OS, while those furthest away (&gt;200km) had the poorest OS (p&lt;0.05). In a univariate Cox regression model, rural patients had a mortality ratio of 1.18 (p &lt;0.05), and those living 200km or more from Winnipeg had a mortality ratio of 1.40 (p = NS). When adjusted for gender, age at BMT, year of BMT, and graft type, distance from HSC was not a significant predictor of mortality. Only period of BMT and graft type were significant predictors. A relative survival analysis was also conducted. This model included only those variables available in population data (age at BMT, gender, distance from Winnipeg, year of BMT). In univariate analysis, rural patients had an excess mortality ratio of 1.35 (p &lt;0.05), and those living more than 200 km from Winnipeg had had an excess mortality ratio of 1.52 (p = NS). However, in the adjusted relative survival analysis, distance from Winnipeg was not a significant predictor. Again, period of BMT was a significant predictor. 432 Manitobans were diagnosed with HL. 182 (42%) were rural, and 250 (58%) were urban. This was similar to 2006 Canadian census data for Manitoba, (54% urban). In contrast, 69% of patients undergoing transplant for HL were urban.
Conclusions: Previous research has suggested that rural patients undergoing BMT have a higher risk of death. Using population-based data from a Canadian province, we were unable to demonstrate this finding. Both the Cox regression model and the relative survival analysis demonstrated non-significant associations between location and mortality after controlling for other variables. This may be due to relatively small number of patients residing 200 or more km from Winnipeg in our study. However, the non-significant relationship may also be due to more comprehensive long-term follow-up of patients within the BMT program. Lastly, there may be under-utilization of BMT in rural populations; this is an area that deserves further study.