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Past Projects – Selected work

Health Service Access

Access to health care services is a key feature in shaping population health and is impacted by a variety of different factors, including spatial and aspatial factors.  It is also an overarching theme in the research conducted by the CHaSE lab.  Utilizing spatial analysis in combination with statistical methods, the lab conducts specialized research examining the impact of spatial access on healthcare outcomes.   The findings of such research can be used to  identify underserved communities where changes in the provision of health care services could have the greatest impact.


Assessing the relationship between physician availability and viral load suppression in British Columbia


Different areas of physician availability across BC (poor, intermediate and good) as a result of overlapping individual catchments. Depicted in yellow are one hour catchments around population centers which are located within areas of poor physician availability and how many individuals reside within each yellow catchment.
Note: blue lines represent roads in catchments classified according to physician availability as follows: light blue lines for poor availability, medium blue lines for intermediate availability, and dark blue lines for good availability.

Click here to see an interactive map showing changes in viral load supression in BC from 2003 to 2015.


Assessing access to paediatric trauma centres in Canada, and the impact of the golden hour on length of stay at the hospital: an observational study


The above map of Canadian pediatric trauma centres (PTCs) calculates a one-hour driving time catchment (also known as the golden hour) around each PTC, indicating the proportion of children aged 0–19 years within each catchment.



A comparative analysis of potential spatio-temporal access to palliative care services in two Canadian provinces


The above figure highlights patterns of palliative service within the province of Saskatchewan. As indicated, services are more concentrated in the Southern areas, but are spread throughout this relatively rural region. This pattern of service provision is related to the topography of the prairies, as well to the support for small rural hospitals (as opposed to the centralization of services).


Spatial Epidemiology


Hospitalizations due to unintentional transport injuries among Aboriginal population of British Columbia, Canada: Incidence, changes over time and ecological analysis of risk markers

Background: Worldwide, Indigenous people have disproportionately higher rates of transport injuries. We examined disparities in injury-related hospitalizations resulting from transport incidents for three population groups in British Columbia (BC): total population, Aboriginal off-reserve, and Aboriginal on-reserve populations. We also examined sociodemographic, geographic and ethnic risk markers for disparities. Methods:
We identified Aboriginal people through BC’s universal health care insurance plan insurance premium group and birth and death record notations. We calculated crude incidence rate and Standardized Relative Risk (SRR) of hospitalization for unintentional transport injury, standardized for age, gender and Health Service Delivery Area (HSDA), relative to the total population of BC. We tested hypothesized associations of geographic, socio-economic, and employment-related characteristics of Aboriginal communities with SRR of transport injury by multivariable linear regression. Results: During the period 1991–2010, the SRR for the off-reserve Aboriginal population was 1.77 (95% CI: 1.71 to 1.83); and 2.00 (95% CI: 1.93 to 2.07) among those living on-reserve. Decline in crude rate and SRRs was observed over this period among both the Aboriginal and total populations of BC, but was proportionally greater among the Aboriginal population. The best-fitting multivariable risk marker model was an excellent fit (R2 = 0.912, p<0.001), predicted SRRs very close to observed values, and retained the following terms: urban residence, population per room, proportion of the population with a high school certificate, proportion of the population employed; and multiplicative interactions of Aboriginal ethnicity with population per room and proportion of the population employed. Conclusions:
Disparities in risk of hospitalization due to unintentional transport injury have narrowed. Aboriginal ethnicity modifies the effects of socioeconomic risk factors. Continued improvement of socioeconomic conditions and implementation of culturally relevant injury prevention interventions are needed.

Standardized Rate Ratio of hospital separations due to unintentional transport injuries by HSDA, British Columbia, 1991–2010.


Click here to see an interactive map showing unintentional transport injuries in BC 1991 – 2010.

A geospatial analysis of the relationship between neighbourhood socioeconomic status and adult severe injury in Greater Vancouver

Injuries are a leading cause of death among children 14 years of age and younger, as well as one of the main causes of morbidity. Within this population, Traumatic Brain Injuries (TBI) are the most common cause of mortality, responsible for approximately 75% of injury-related deaths. Injury rates are particularly high for children of lower socio economic status. Using spatial analysis techniques, this project examines the social and environmental factors influencing rates of injury and identifies areas where rates are particularly high.  The results of this analysis can be used to implement injury prevention programs for those populations most affected.

This map identifies clusters of high injury rates (all causes) overlapped by high social deprivation within metro Vancouver (Canada). Policies and programs aimed at reducing the rates of severe injury by augmenting the social environment would have the greatest benefit in these areas.


Multiple Sclerosis

The Use of Satellite Data to Measure Ultraviolet-B Penetrance and Its Potential Association with Age of Multiple Sclerosis Onset

Background: Studies have indicated an association between low Ultraviolet B (UVB) exposure and an increased risk of developing multiple sclerosis (MS). Few studies, however, have explored whether UVB exposure is associated with the age at MS symptom onset. Objective: We investigated the potential association between cumulative early life ambient UVB exposure and age at MS onset, using satellite data to measure ambient UVB exposure. Methods: Adult onset MS patients were selected from the University of British Columbia’s MS genetic database (1980–2005). Patients’ places of residence from birth to age 18 years were geocoded (latitude and longitude) and assigned UVB values using NASA’s Total Ozone Mapping Spectrometer (TOMS) dataset. Linear regression was used to explore the relationship between cumulative UVB exposure (measured for age periods 0–6, 7–12, 13–18, 0–12, and 0–18) and age at MS onset. Results: 3226 patients were included in the analysis. Of these, 74% were female, with an overall mean symptom onset age of 33.3 years. At onset, a total of 2944 (91%) had a relapsing-remitting disease course, 254 (8%) had primary progressive and the disease course for 28 (1%) was unknown. No significant associations between cumulative early life ambient UVB exposure and age at MS onset were observed. Patient sex, MS phenotype, and immigration to Canada after age 18 were significantly associated with age of onset (p < 0.01). Conclusions: Early life ambient UVB, as measured by satellite imagery, was not significantly associated with the age at MS onset.


Multiple Sclerosis

A proposed methodology to estimate the cumulative life-time UVB exposure using geographic information systems: An application to multiple sclerosis

Several studies have indicated that the development of Multiple Sclerosis (MS) is directly correlated to Ultraviolet B radiation (UVB) exposure. It is widely hypothesized that reduced Vitamin D (which is attributed to lack of exposure to UVB), especially during the first fifteen years of life, may be associated with an increased risk of MS. Earlier studies, indicating that the frequency of MS was greater between latitudes of 45 and 64 degrees than it was at lower latitudes, had two primary shortcomings: first, the use of a single latitude for the assignation of UV-B exposure, and second, the disregard  for the role of life history, and particularly, the role of UV-B exposure at key points in the patient’s history. The results depicted below use a novel methodology to derive UVB exposure using satellite data, thereby overcoming these shortcomings.

The above figure indicates patterns of cumulative UVB exposure for Multiple Sclerosis patients. Increased sun exposure is shown as a gradient from yellow to red with increases in age depicted by the height of the lines. The trajectories represent changes in the patient’s place of residence from birth to age of MS onset.