Does core area theory apply to sexually transmitted diseases in rural environments?

BACKGROUND: Our objective was to determine the extent to which geographical core areas for gonorrhea and syphilis are located in rural areas as compared with urban areas. METHODS: Incident gonorrhea (January 1, 2005-December 31, 2010) and syphilis (January 1, 1999-December 31, 2010) rates were estimated and mapped by census tract and quarter. Rurality was measured using percent rural and rural-urban commuting area (rural, small town, micropolitan, or urban). SaTScan was used to identify spatiotemporal clusters of significantly elevated rates of infection. Clusters lasting 5 years or longer were considered core areas; clusters of shorter duration were considered outbreaks. Clusters were overlaid on maps of rurality and qualitatively assessed for correlation. RESULTS: Twenty gonorrhea core areas were identified: 65% were in urban centers, 25% were in micropolitan areas, and the remaining 10% were geographically large capturing combinations of urban, micropolitan, small town, and rural environments. Ten syphilis core areas were identified with 80% in urban centers and 20% capturing 2 or more rural-urban commuting areas. All 10 (100%) of the syphilis core areas overlapped with gonorrhea core areas. CONCLUSIONS: Gonorrhea and syphilis rates were high for rural parts of North Carolina; however, no core areas were identified exclusively for small towns or rural areas. The main pathway of rural sexually transmitted disease (STI) transmission may be through the interconnectedness of urban, micropolitan, small town, and rural areas. Directly addressing STIs in urban and micropolitan communities may also indirectly help address STI rates in rural and small town communities.

Access to diagnostic imaging and incidental detection of differentiated thyroid cancer in Ontario: A population-based retrospective cohort study.

Global increases in thyroid cancer incidence (≥90% differentiated thyroid cancers; DTC) are hypothesized to be related to increased use of pre-diagnostic imaging. These procedures can detect DTC during imaging for conditions unrelated to the thyroid (incidental detection). The objectives were to evaluate incidental detection of DTC associated with standardized, regional imaging capacity and drivetime from patient residence to imaging facility (the exposures). We conducted a population-based retrospective cohort study of 32,097 DTC patients in Ontario, 2003-2017. We employed sex-specific spatial Bayesian hierarchical models to evaluate the exposures and examine the adjusted odds of incidental detection by administrative regions. Regional capacities of computed tomography and magnetic resonance imaging scanners are positively associated with incidental detection, but vary by sex. Contrary to hypothesis, drivetimes in urban areas are positively associated with incidental detection. Access to primary care may play a role in several administrative regions with higher adjusted odds of incidental detection.

Feasibility and utility of mapping disease risk at the neighbourhood level within a Canadian public health unit: an ecological study.

BACKGROUND: We conducted spatial analyses to determine the geographic variation of cancer at the neighbourhood level (dissemination areas or DAs) within the area of a single Ontario public health unit, Wellington-Dufferin-Guelph, covering a population of 238,326 inhabitants. Cancer incidence data between 1999 and 2003 were obtained from the Ontario Cancer Registry and were geocoded down to the level of DA using the enhanced Postal Code Conversion File. The 2001 Census of Canada provided information on the size and age-sex structure of the population at the DA level, in addition to information about selected census covariates, such as average neighbourhood income. RESULTS: Age standardized incidence ratios for cancer and the prevalence of census covariates were calculated for each of 331 dissemination areas in Wellington-Dufferin-Guelph. The standardized incidence ratios (SIR) for cancer varied dramatically across the dissemination areas. However, application of the Moran's I statistic, a popular index of spatial autocorrelation, suggested significant spatial patterns for only two cancers, lung and prostate, both in males (p < 0.001 and p = 0.002, respectively). Employing Bayesian hierarchical models, areas in the urban core of the City of Guelph had significantly higher SIRs for male lung cancer than the remainder of Wellington-Dufferin-Guelph; and, neighbourhoods in the urban and surrounding rural areas of Orangeville exhibited significantly higher SIRs for prostate cancer. After adjustment for age and spatial dependence, average household income attenuated much of the spatial pattern of lung cancer, but not of prostate cancer. CONCLUSION: This paper demonstrates the feasibility and utility of a systematic approach to identifying neighbourhoods, within the area served by a public health unit, that have significantly higher risks of cancer. This exploratory, ecologic study suggests several hypotheses for these spatial patterns that warrant further investigations. To the best of our knowledge, this is the first Canadian study published in the peer-reviewed literature estimating the risk of relatively rare public health outcomes at a very small areal level, namely dissemination areas.

Incidental detection, imaging modalities and temporal trends of differentiated thyroid cancer in Ontario: a population-based retrospective cohort study.

BACKGROUND: Incidence rates of thyroid cancer in Ontario have increased more rapidly than those of any other cancer, whereas mortality rates have remained relatively stable. We evaluated the extent to which incidental detection of differentiated thyroid cancer during unrelated prediagnostic imaging procedures contributed to Ontario's incidence rates. METHODS: We conducted a retrospective cohort study involving Ontarians who received a diagnosis of differentiated thyroid cancer from 1998 to 2017 using linked health care administrative databases. We classified cases as incidentally detected if a nonthyroid diagnostic imaging test (e.g., computed tomography [CT]) preceded an index event (e.g., prediagnostic fine-needle aspiration biopsy); all other cases were nonincidentally detected cases. We used Joinpoint and negative binomial regressions to characterize sex-specific rates of differentiated thyroid cancer by incidentally detected status and to quantify potential age, diagnosis period and birth cohort effects. RESULTS: The study included 36 531 patients with differentiated thyroid cancer, of which 78.7% were female. Incidentally detected cases increased from 7.0% to 11.0% of female patients and from 13.5% to 18.2% of male patients over the study period. Age-standardized incidence rates increased more rapidly for incidentally detected cases (4.2-fold for female and 3.7-fold for male patients) than for nonincidentally detected cases (2.6-fold for female and 3.0-fold for male patients; p < 0.001). Diagnosis period was the primary factor associated with increased incidence rates of differentiated thyroid cancer, adjusting for other factors. Within each period, incidentally detected rates increased faster than nonincidentally detected rates, adjusting for age. Our results showed that CT was the most common imaging procedure preceding incidentally detected diagnoses. INTERPRETATION: Incidentally detected cases represent a large and increasing component of the observed increases in differentiated thyroid cancer in Ontario over the past 20 years, and CT scans are primarily associated with these cases despite the modality having similar, increasing rates of use compared with magnetic resonance imaging (1993-2004). Recent increases in rates of differentiated thyroid cancer among males and incidentally detected cases among females in Ontario appear to be unrelated to birth cohort effects.

A Bayesian shared components modeling approach to develop small area indicators of social determinants of health with measures of uncertainty.

OBJECTIVES: Existing Canadian social determinants of health (SDOH) indicators do not quantify uncertainty to identify priority areas. The objectives of this methodologic study were: (1) to estimate and map small area (dissemination area) shared and variable-specific SDOH indicators with measures of uncertainty using a Bayesian model that accounts for spatial dependence; (2) to quantify geographic variation in the SDOH indicators and their contribution to a shared indicator; and (3) to assess the SDOH indicators' associations with behavioural risk factors and their consistency with the Ontario Marginalization Index (ON-Marg). METHODS: Lower education-, income-, unemployment-, living alone- and visible minority-related variables used in existing Canadian SDOH indices were fit as dependent variables to a Bayesian model to produce area-based SDOH indicators that were mapped with measures of uncertainty in two study areas. The fractions of spatial variation explained by the model components were computed. Bayesian analysis of variance was used to examine the SDOH indicator associations with behavioural risk factors and their consistency with ON-Marg examined using Pearson's correlation coefficient. RESULTS: The shared component was strongly associated with material deprivation (i.e., income) in each study area; however, variable-specific SDOH indicators were important too. The SDOH indicators were associated with behavioural risk factors for chronic disease, particularly alcohol consumption and smoking, and the shared component estimates were consistent with the ON-Marg material deprivation. CONCLUSIONS: The Bayesian approach to produce SDOH indicators met the three study objectives and as such provides a new approach to prioritize areas that may experience health inequalities.

Cancer screening barriers and facilitators for under and never screened populations: A mixed methods study.

BACKGROUND: Cancer screening is below targets in Ontario, Canada. Our objective was to identify and quantify the barriers and facilitators for breast, cervical and colorectal cancer screening for under and never screened (UNS) residents living in Ontario between 2011 and 2013. METHODS: We used a multi-phased mixed methods study design. Results from thematic analysis of focus group discussions with health care providers and UNS community members were used to develop an on-line, province-wide, cross-sectional survey to estimate the prevalence of barriers and facilitators for the provincial population. Adjusted prevalence odds ratios and 95% confidence intervals were estimated for UNS compared to regularly screened participants using logistic regression. RESULTS: Four focus groups were held with health service providers and sixteen with UNS community members. Top barriers and facilitators themed around provider-patient communication, fear and embarrassment, history of physical or sexual abuse, social determinants of health (including low literacy, lack of awareness, and health insurance), symptoms appearing, and family and friends. 3075 participants completed the online survey. Compared to regularly screened participants, UNS had significantly higher odds of reporting: no regular health care provider; not feeling comfortable talking about screening; or the Doctor or Nurse Practitioner not suggesting screening. UNS also had significantly higher odds of reporting the facilitators: the test being less scary/painful or uncomfortable; friend/family insisting on getting screened; starting to have symptoms; or an easier test that could be done at home. CONCLUSIONS: Interventions addressing fear through individual, interpersonal and structural facilitators may increase cancer screening.