Geographical variation and factors associated with gastric cancer in Manitoba.

OBJECTIVES: We investigated the spatial disparities and factors associated with gastric cancer (GC) Incidence in Manitoba. METHODS: We combined information from Manitoba Cancer registry and Census data to obtain an age-sex adjusted relative risk (IRR) of GC incidence. We geocoded the IRR to the 96 regional health authority districts (RHADs) using the postal code conversion file (PCCF). Bayesian spatial and spatio-temporal Poisson regression models were used for the analysis. RESULTS: Adjusting for the effect of socio-economic score index (SESI), Indigenous, and immigrant population, 25 districts with high overall GC risk were identified. One unit increase in SESI was associated with reduced risk of cardia GC (CGC) by 14% (IRR = 0.859; 95% CI: 0.780-0.947) and the risk of non-cardia GC (NCGC) by approximately 10% (IRR = 0.898; 95% CI: 0.812-0.995); 1% increase in regional Indigenous population proportion reduced the risk of CGC by 1.4% (IRR = 0.986; 95% CI: 0.978-0.994). In the analysis stratified by sex, one unit increase in SESI reduced the risk of CGC among women by 26.2% (IRR = 0.738; 95% CI: 0.618-0.879), and a 1% increase in Indigenous population proportion reduced the risk of CGC among women by 1.9% (IRR = 0.981; 95% CI: 0.966-0.996). CONCLUSION: Our results support a significant association between SESI and NCGC. We report regional variation of GC IRR and a varying temporal pattern across the RHADs. These results could be used to prioritize interventions for regions with high and progressive risk of GC.

Geographical Variation and Factors Associated With Inflammatory Bowel Disease in a Central Canadian Province.

BACKGROUND: We investigated temporal trends, geographical variation, and geographical risk factors for incidence of inflammatory bowel disease (IBD). METHODS: We used the University of Manitoba IBD Epidemiology Database to identify incident IBD cases diagnosed between 1990 and 2012, which were then geocoded to 296 small geographic areas (SGAs). Sociodemographic characteristics of the SGAs (proportions of immigrants, visible minorities, Indigenous people, and average household income) were obtained from the 2006 Canadian Census. The geographical variation of IBD incidence was modeled using a Bayesian spatial Poisson model. Time trends of IBD incidence were plotted using Joinpoint regression. RESULTS: The incidence of IBD decreased over the study years from 23.6 (per 100,000 population) in 1990 to 16.3 (per 100,000 population) in 2012. For both Crohn's disease (CD) and ulcerative colitis (UC), the highest incidence was in Winnipeg and the southern and central regions of Manitoba, whereas most of northern Manitoba had lower incidence. There was no effect of sociodemographic characteristics of SGAs, other than the proportion of Indigenous people, which was associated with lower IBD incidence. CONCLUSIONS: Although the incidence of IBD in Manitoba is decreasing over time, we have identified geographic areas with persistently higher IBD incidence that warrant further study for etiologic clues.

Health-related quality of life and economic burden to smoking behaviour among Canadians.

OBJECTIVES: The objectives of this study were to: (1) examine whether the smoking status of the Canadian population is associated with a reduction in health-related quality of life (HRQoL); (2) calculate the overall economic burden of loss in HRQoL using a commonly accepted $100,000 willingness-to-pay (WTP) threshold to gain one quality-adjusted life year (QALY); and (3) calculate the loss of HRQoL over a lifetime. METHODS: We used the 2015 Canadian Community Health Survey. The variations in HRQoL were estimated using a multivariable generalized linear model. Total expected lifetime QALYs lost due to smoking were calculated by compounding the annual adjusted health utility loss associated with smoking across a respondent's remaining years of life expectancy stratified by age. A discount rate of 1.5% was applied to the analysis based on recent analysis of the costs of borrowing in Canada. RESULTS: Smoking is significantly associated with HRQoL loss. This study demonstrated that smoking is associated with a 0.05 and 0.01 reduction in Health Utilities Index Mark 3 (HUI3) score for current and former smokers, which also corresponds to a loss of 0.66 quality-adjusted life years in average, and also is associated with substantial individual and societal economic cost. The total lifetime economic burden of HUI3 loss per smoker was $65,935, yielding in the aggregate a societal burden of $1068.88 billion in the study population. CONCLUSION: Tobacco control, prevention and intervention not only will improve HRQoL but also will generate social returns on investment.

The effects of cigarette price and the amount of pocket money on youth smoking initiation and intensity in Canada.

OBJECTIVES: To investigate the price and income elasticities of adolescent smoking initiation and intensity to determine the extent to which increased pocket money leads to greater smoking among youth, and whether higher taxes can mitigate this effect. METHODS: We used the 2012/2013 Canadian Youth Smoking Survey including students in grades 7-12. The multivariable logistic regression was used to examine the probability of smoking initiation, and a linear regression to examine the smoking intensity determined by province-level prices of cigarettes, pocket money, and a vector of individual characteristics, including age, sex, race, and school-related and psychosocial factors. RESULTS: Of respondents, 28.8% have tried cigarette smoking. More than 90% of these initiated smoking between age 9 and 17. Male smokers consumed a higher average number of whole cigarettes daily than did females. The price elasticity of smoking initiation and intensity for youth in the full sample were - 1.13 and - 1.02, respectively, which means that a 10% increase in price leads to an 11.3% reduction in initiation and a 10.2% reduction in intensity. The income elasticity of smoking initiation and intensity for youth in the full sample were 0.07 and 0.06, respectively, which means that a 10% increase in income leads to a 0.7% increase in initiation and a 0.6% increase in intensity. CONCLUSION: Economic measures such as taxation that raise the price of cigarettes may be a useful policy tool to limit smoking initiation and intensity.

Geographical Variation and Factors Associated with Non-Small Cell Lung Cancer in Manitoba.

BACKGROUND: Screening decreases non-small cell lung cancer (NSCLC) deaths and is recommended by the Canadian Task Force on Preventive Health Care. We investigated risk factor prevalence and NSCLC incidence at a small region level to inform resource allocation for lung cancer screening. METHODS: NSCLC diagnoses were obtained from the Canadian Cancer Registry, then geocoded to 283 small geographic areas (SGAs) in Manitoba. Sociodemographic characteristics of SGAs were obtained from the 2006 Canadian Census and Canadian Community Health Survey. Geographical variation was modelled using a Bayesian spatial Poisson model. RESULTS: NSCLC incidence in SGAs ranged from 1 to 343 cases per 100,000 population per year. The highest incidence rates were in the Southeastern, Southwestern, and Central regions of Manitoba, while most of Northern Manitoba had lower rates. Poisson regression suggested areas with higher proportions of Aboriginal people and higher average income, and immigrants had lower NSCLC incidence whereas areas with higher proportions of smokers had higher incidence. CONCLUSION: On an SGA level, smoking rates remain the most significant factor driving NSCLC incidence. Socioeconomic status and proportions of immigrants or Aboriginal peoples independently impact NSCLC rates. We have identified SGAs in Manitoba to target in policy and infrastructure planning for lung cancer screening.

Time and spatial trends in lymphoid leukemia and lymphoma incidence and survival among children and adolescents in Manitoba, Canada: 1984-2013.

OBJECTIVES: To test for time and spatial trends in lymphoid malignancies, including lymphoid leukemia (LL), Hodgkin lymphoma (HL), and non-Hodgkin lymphoma (NHL), in children and adolescents in the province of Manitoba, Canada. METHODS: Incident cases diagnosed between 1984 and 2013 were identified from the Manitoba Cancer Registry. We assessed time trends in age-standardized incidence rates using joinpoint regression and in 5-year relative survival using Poisson regression model. Kulldorff's scan method was used to assess spatial variation and clustering. RESULTS: Age-standardized incidence rates (per million person-years) in males and females were 34.0 (95% confidence interval [CI] 28.9-39.1) and 26.2 (95% CI 21.5-30.7) for LL, 10.5 (95% CI 7.7-13.3) and 12.5 (95% CI 9.4-15.7) for HL, 12.5 (95% CI 9.3-15.4) and 7.7 (95% CI 5.2-10.2) for NHL (except for Burkitt lymphomas), and 3.2 (95% CI 1.6-4.7) and 1.5 (95% CI 0.4-2.5) for Burkitt lymphomas. Age- and sex- standardized LL incidence rate increased 1.4% (95% CI 0.3%-2.5%) per year, while the changes for HL and NHL incidence rates were not statistically significant. There were geographic differences in age-standardized incidence rates for LL, HL, and NHL and spatial clusters were detected in southern part of the province. Five-year relative survival has improved over time and there was no difference between rural and urban areas. CONCLUSIONS: Lymphoid leukemia incidence rate increased over time and varied by geographic area. Further research should examine the factors contributing to these trends.

Geographic variation and factors associated with colorectal cancer incidence in Manitoba.

OBJECTIVES: Although individuals living in areas with lower household income have been shown to have higher rates of mortality from colorectal cancer (CRC), findings on the effect of income on CRC incidence in countries with universal health care have been inconsistent. There are limited data from Canada. We investigated the geographic variation and factors associated with CRC incidence in Manitoba, a central Canadian province. METHODS: The Manitoba Cancer Registry and Manitoba Health population registry were used to determine age-sex-standardized CRC incidence rates between 1985 and 2012, which were geocoded to 498 small geographic areas (SGAs). The 2001 Canadian Census was used to determine the socio-demographic characteristics of the SGAs. Bayesian spatial Poisson modelling was used to assess geographic variation and factors associated with CRC incidence. RESULTS: CRC incidence in SGAs ranged from 11 to 1026 per 100 000 population per year. Importantly, in the fully adjusted model there was no significant association between either average household income or proportion of recent immigrants in the SGAs and CRC incidence. Individuals living in urban areas had an overall lower CRC incidence (incidence rate ratio: 0.76; 95% credible interval: 0.58-0.98). CONCLUSIONS: In a province with a universal health care system, our study suggests there are no disparities in CRC incidence by socio-economic level of the areas of residence. Rural areas should be a focus of CRC reduction initiatives in Manitoba. Similar analysis in other jurisdictions should be performed to evaluate the effect of the characteristics of SGAs on CRC incidence in different settings and target some of the efforts to reduce CRC burden.

Hierarchical multivariate mixture generalized linear models for the analysis of spatial data: An application to disease mapping.

Disease mapping of a single disease has been widely studied in the public health setup. Simultaneous modeling of related diseases can also be a valuable tool both from the epidemiological and from the statistical point of view. In particular, when we have several measurements recorded at each spatial location, we need to consider multivariate models in order to handle the dependence among the multivariate components as well as the spatial dependence between locations. It is then customary to use multivariate spatial models assuming the same distribution through the entire population density. However, in many circumstances, it is a very strong assumption to have the same distribution for all the areas of population density. To overcome this issue, we propose a hierarchical multivariate mixture generalized linear model to simultaneously analyze spatial Normal and non-Normal outcomes. As an application of our proposed approach, esophageal and lung cancer deaths in Minnesota are used to show the outperformance of assuming different distributions for different counties of Minnesota rather than assuming a single distribution for the population density. Performance of the proposed approach is also evaluated through a simulation study.

Geographical variation in the incidence of childhood leukaemia in Manitoba.

BACKGROUND: Identification of geographical areas and ecological factors associated with higher incidence of childhood leukaemias can direct further study for preventable factors and location of health services to manage such individuals. AIM: The aim of this study was to describe the geographical variation and the socio-demographic factors associated with childhood leukaemia in Manitoba. METHODS: Information on childhood leukaemia incidence between 1992 and 2008 was obtained from the Canadian Cancer Registry and the socio-demographic characteristics for the area of residence from the 2006 Canadian Census. Bayesian spatial Poisson mixed models were used to describe the geographical variation of childhood leukaemia and to determine the association between childhood leukaemia and socio-demographic factors. RESULTS: The south-eastern part of the province had a higher incidence of childhood leukaemia than other parts of the province. In the age and sex-adjusted Poisson regression models, areas with higher proportions of visible minorities and immigrant residents had higher childhood leukaemia incidence rate ratios. In the saturated Poisson regression model, the childhood leukaemia rates were higher in areas with higher proportions of immigrant residents. Unemployment rates were not a significant factor in leukaemia incidence. CONCLUSION: In Manitoba, areas with higher proportions of immigrants experience higher incidence rates of childhood leukaemia. We have identified geographical areas with higher incidence, which require further study and attention.

Geographical variation and factors associated with colorectal cancer mortality in a universal health care system.

OBJECTIVE: To investigate the geographical variation and small geographical area level factors associated with colorectal cancer (CRC) mortality. METHODS: Information regarding CRC mortality was obtained from the population-based Manitoba Cancer Registry, population counts were obtained from Manitoba's universal health care plan Registry and characteristics of the area of residence were obtained from the 2001 Canadian census. Bayesian spatial Poisson mixed models were used to evaluate the geographical variation of CRC mortality and Poisson regression models for determining associations with CRC mortality. Time trends of CRC mortality according to income group were plotted using joinpoint regression. RESULTS: The southeast (mortality rate ratio [MRR] 1.31 [95% CI 1.12 to 1.54) and southcentral (MRR 1.62 [95% CI 1.35 to 1.92]) regions of Manitoba had higher CRC mortality rates than suburban Winnipeg (Manitoba's capital city). Between 1985 and 1996, CRC mortality did not vary according to household income; however, between 1997 and 2009, individuals residing in the highest-income areas were less likely to die from CRC (MRR 0.77 [95% CI 0.65 to 0.89]). Divergence in CRC mortality among individuals residing in different income areas increased over time, with rising CRC mortality observed in the lowest income areas and declining CRC mortality observed in the higher income areas. CONCLUSIONS: Individuals residing in lower income neighbourhoods experienced rising CRC mortality despite residing in a jurisdiction with universal health care and should receive increased efforts to reduce CRC mortality. These findings should be of particular interest to the provincial CRC screening programs, which may be able to reduce the disparities in CRC mortality by reducing the disparities in CRC screening participation.

Bowel disorders and its spatial trend in Manitoba, Canada.

BACKGROUND: Bowel disorders have destructive impacts on the patients social and mental aspects of life and can cause emotional distress. The risk of developing bowel incontinence also increases with age. The rate of incidence of inflammatory bowel disease in Manitoba, Canada, has been unusually raised. Therefore, it is important to identify trends in the incidence of bowel disorders that may suggest further epidemiological studies to identify risk factors and identify any changes in important factors. METHODS: An important part of spatial epidemiology is cluster detection as it has the potential to identify possible risk factors associated with disease, which in turn may lead to further investigations into the nature of diseases. To test for potential disease clusters many methods have been proposed. The focused detection methods including the circular spatial scan statistic (CSS), flexible spatial scan statistic (FSS), and Bayesian disease mapping (BYM) are among the most popular disease detection procedures. A frequentist approach based on maximum likelihood estimation (MLE) has been recently used to identify potential focused clusters as well. The aforementioned approaches are studied by analyzing a dataset of bowel disorders in the province of Manitoba, Canada, from 2001 to 2010. RESULTS: The CSS method identified less regions than the FSS method in the south part of the province as potential clusters. The same regions were identified by the BYM and MLE methods as being potential clusters of bowel disorders with a slightly different order of significance. Most of these regions were also detected by the CSS or FSS methods. CONCLUSIONS: Overall, we recommend using the methods BYM and MLE for cluster detection with the similar population and structure of regions as in Manitoba. The potential clusters of bowel disorders are generally located in the southern part of the province including the eastern part of the city of Winnipeg. These results may represent real increases in bowel disorders or they may be an indication of other covariates that were not adjusted for in the model used here. Further investigation is needed to examine these findings, and also to explore the cause of these increases.