Rural surgeons are often uneasy when their outcomes are compared with those of urban surgeons because they perceive that rural patients typically present with worse disease. Rural patients with cancer are commonly thought to present at a later stage of disease, although this is based largely on anecdotal evidence.
Retrospective, descriptive analysis of cancer stage at presentation of rural versus urban patients with two common cancers (lung, colorectal) using the Surveillance, Epidemiology, and End Results database from the National Cancer Institute. Rural versus urban designations were based on rural-urban continuum codes from the US Department of Agriculture. We constructed an ordinal logistic regression model to compare stage at presentation between rural and urban colorectal and lung cancer patients, while controlling for other factors that might be associated with late stage at presentation, including age, race, gender, marital status, income level, and level of education.
In univariate and multivariate analyses, patients with colorectal and lung cancer from rural areas were not more likely to present at later stage. The ordinal logistic regression model indicated that urban patients are more likely to present with late-stage colorectal and lung cancer, compared with rural patients (p < 0.001). For colon cancer, other factors notably associated with stage IV disease were low-income, African-American race, age younger than 65 years, divorce, male gender, and language isolation. For lung cancer, factors notably associated with stage IV disease were African-American race, divorce, male gender, and language isolation.
Urban rather than rural residence appears to be associated with later stages of lung and colorectal cancer at presentation. This finding is contrary to the common assumption that rural patients present at later stages of disease.
"There is also interest in urban–rural differences and spatial variation in stage at diagnosis. For example a study using SEER data reports that urban as opposed to rural residence is associated with stage at diagnosis for lung and colorectal cancer  and there is also substantial geographic variation late stage breast and colorectal cancer diagnosis [27,28]. Access to care and the distribution of race-ethnic groups are associated with county level variation in stage at diagnosis identified in some of these studies, but considerable unaccounted for variation between counties remains. "
[Show abstract][Hide abstract] ABSTRACT: Urban sprawl has the potential to influence cancer mortality via direct and indirect effects on obesity, access to health services, physical activity, transportation choices and other correlates of sprawl and urbanization.
This paper presents a cross-sectional analysis of associations between urban sprawl and cancer mortality in urban and suburban counties of the United States. This ecological analysis was designed to examine whether urban sprawl is associated with total and obesity-related cancer mortality and to what extent these associations differed in different regions of the US. A major focus of our analyses was to adequately account for spatial heterogeneity in mortality. Therefore, we fit a series of regression models, stratified by gender, successively testing for the presence of spatial heterogeneity. Our resulting models included county level variables related to race, smoking, obesity, access to health services, insurance status, socioeconomic position, and broad geographic region as well as a measure of urban sprawl and several interactions. Our most complex models also included random effects to account for any county-level spatial autocorrelation that remained unexplained by these variables.
Total cancer mortality rates were higher in less sprawling areas and contrary to our initial hypothesis; this was also true of obesity related cancers in six of seven U.S. regions (census divisions) where there were statistically significant associations between the sprawl index and mortality. We also found significant interactions (p < 0.05) between region and urban sprawl for total and obesity related cancer mortality in both sexes. Thus, the association between urban sprawl and cancer mortality differs in different regions of the US.
Despite higher levels of obesity in more sprawling counties in the US, mortality from obesity related cancer was not greater in such counties. Identification of disparities in cancer mortality within and between geographic regions is an ongoing public health challenge and an opportunity for further analytical work identifying potential causes of these disparities. Future analyses of urban sprawl and health outcomes should consider exploring regional and international variation in associations between sprawl and health.
International Journal of Health Geographics 01/2014; 13(1):3. DOI:10.1186/1476-072X-13-3 · 2.62 Impact Factor
"In Australia however rural inequalities in colorectal cancer survival have remained even after adjusting for spread of disease . While it may be logical to suggest that rural people are diagnosed with more advanced cancers, a US study found that the opposite was true, in that urban patients were more likely to present with later stage colorectal cancer than rural patients . So although disease stage could potentially explain a portion of the observed rural inequalities in colorectal cancer survival, it is unlikely to be the sole explanation. "
[Show abstract][Hide abstract] ABSTRACT: In Australia, associations between geographic remoteness, socioeconomic disadvantage, and colorectal cancer (CRC) survival show that survival rates are lowest among residents of geographically remote regions and those living in disadvantaged areas. At present we know very little about the reasons for these inequalities, hence our capacity to intervene to reduce the inequalities is limited.
This study, the first of its type in Australia, examines the association between CRC survival and key area- and individual-level factors. Specifically, we will use a multilevel framework to investigate the possible determinants of area- and individual-level inequalities in CRC survival and quantify the relative contribution of geographic remoteness, socioeconomic and demographic factors, disease stage, and access to diagnostic and treatment services, to these inequalities. The multilevel analysis will be based on survival data relating to people diagnosed with CRC in Queensland between 1996 and 2005 (n = 22,723) from the Queensland Cancer Registry (QCR), area-level data from other data custodians such as the Australian Bureau of Statistics, and individual-level data from the QCR (including extracting stage from pathology records) and Queensland Hospitals. For a subset of this period (2003 and 2004) we will utilise more detailed, individual-level data (n = 1,966) covering a greater range of risk factors from a concurrent research study. Geo-coding and spatial technology will be used to calculate road travel distances from patients' residence to treatment centres. The analyses will be conducted using a multilevel Cox proportional hazards model with Level 1 comprising individual-level factors (e.g. occupation) and level 2 area-level indicators of remoteness and area socioeconomic disadvantage.
This study focuses on the health inequalities for rural and disadvantaged populations that have often been documented but poorly understood, hence limiting our capacity to intervene. This study utilises and develops emerging statistical and spatial technologies that can then be applied to other cancers and health outcomes. The findings of this study will have direct implications for the targeting and resourcing of cancer control programs designed to reduce the burden of colorectal cancer, and for the provision of diagnostic and treatment services.
BMC Cancer 01/2010; 10(1):24. DOI:10.1186/1471-2407-10-24 · 3.36 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: IGBT PWM inverter has been concerned that insulation breakdown and irregular voltage distribution on stator winding due to high rate of voltage rise (dv/dt) caused by high-frequency switching and impedance mismatch between inverter and motor. In this paper, voltage distribution in stator windings of induction motor driven by IGBT PWM inverter is studied. To analyze the irregular voltage of stator winding, high frequency parameter is computed by using finite element method (FEM). An equivalent circuit composed by distributed capacitances, inductance, and resistance is derived from these parameters. This equivalent circuit is then used for simulation in order to predict the voltage distribution among the turns and coils. The variable effect on rising time of the inverter and cable length on the voltage distribution is also presented. In order to experiment, an induction motor, 50 [HP], with taps from one phase and a switching surge generator were built to consider the voltage distribution.
Electrical Machines and Systems, 2003. ICEMS 2003. Sixth International Conference on; 12/2003
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