Diabetes medications and cancer risk associations: a systematic review and meta-analysis of evidence over the past 10 years

Diabetes medications may modify the risk of certain cancers. We systematically searched MEDLINE, Embase, Web of Science, and Cochrane CENTRAL from 2011 to March 2021 for studies evaluating associations between diabetes medications and the risk of breast, lung, colorectal, prostate, liver, and pancreatic cancers. A total of 92 studies (3 randomized controlled trials, 64 cohort studies, and 25 case-control studies) were identified in the systematic review, involving 171 million participants. Inverse relationships with colorectal (n = 18; RR = 0.85; 95% CI = 0.78-0.92) and liver cancers (n = 10; RR = 0.55; 95% CI = 0.46-0.66) were observed in biguanide users. Thiazolidinediones were associated with lower risks of breast (n = 6; RR = 0.87; 95% CI = 0.80-0.95), lung (n = 6; RR = 0.77; 95% CI = 0.61-0.96) and liver (n = 8; RR = 0.83; 95% CI = 0.72-0.95) cancers. Insulins were negatively associated with breast (n = 15; RR = 0.90; 95% CI = 0.82-0.98) and prostate cancer risks (n = 7; RR = 0.74; 95% CI = 0.56-0.98). Positive associations were found between insulin secretagogues and pancreatic cancer (n = 5; RR = 1.26; 95% CI = 1.01-1.57), and between insulins and liver (n = 7; RR = 1.74; 95% CI = 1.08-2.80) and pancreatic cancers (n = 8; RR = 2.41; 95% CI = 1.08-5.36). Overall, biguanide and thiazolidinedione use carried no risk, or potentially lower risk of some cancers, while insulin secretagogue and insulin use were associated with increased pancreatic cancer risk.

Mental health, cancer risk, and the mediating role of lifestyle factors in the CARTaGENE cohort study

BACKGROUND

Evidence on the association between mental health disorders and cancer risk is inconclusive, despite well-established associations between mental health disorders and lifestyle factors such as smoking. This study examines the relationships between depression, anxiety and cancer risk, and the potential mediating effects of lifestyle factors.

METHODS

A study of 34,571 participants aged 40-69 years in the CARTaGENE cohort was conducted. Depression was defined by questionnaire (PHQ-9), antidepressant use, and a composite of questionnaire, antidepressant use, or lifetime self-reported physician diagnosis. Anxiety was defined by questionnaire (GAD-7). Co-morbid depression and anxiety was also assessed. Cox regression models were used to investigate associations between mental health and risk of prostate, lung, and all cancers combined. Mediating effects of lifestyle factors were assessed using Baron and Kenny mediation criteria.

RESULTS

There were positive associations between mental health disorders, all cancers and lung cancer risk, however with the exception of anxiety and lung cancer in women (Hazard Ratio [HR] = 1.67, 95% CI: 1.01-2.76), associations were attenuated with adjustment for sociodemographics, health status and lifestyle factors. In the mediation analysis, smoking accounted for 27%, 18%, and 26%, of the total effect between depression (PHQ-9), anxiety, and co-morbidity and lung cancer, respectively in women. In men, smoking accounted for 17% of the total effect between depression (PHQ-9, antidepressant, or lifetime self-report of physician diagnosis) and all cancers.

CONCLUSIONS

Positive associations were observed between mental health disorders, all cancer and lung cancer risk, however most relationships were attenuated with adjustment for lifestyle factors. Smoking status mediated a significant proportion of the relationships between mental health disorders and cancer risk.

Arsenic Speciation and Metallomics Profiling of Human Toenails as a Biomarker to Assess Prostate Cancer Cases: Atlantic PATH Cohort Study

Chronic exposure to inorganic arsenic and trace metals has been linked to prostate cancer, and altered arsenic methylation capacity may have an important role in arsenic carcinogenesis. Biomarkers may be able to elucidate this role. Our objectives were to characterize profiles of arsenic species and metallome in toenails and urine samples, compare profiles between prostate cancer cases and controls, and determine the discriminant ability of toenail and urine biomarkers. Toenail samples (n = 576), urine samples (n = 152), and questionnaire data were sourced from the Atlantic Partnership for Tomorrow's Health (PATH) cohort study. Healthy controls were matched to prostate cancer cases (3:1 ratio) on sex, age, smoking status, and the province of residence. Metallome profiles and proportions of arsenic species were measured in toenail and urine samples. Analysis of covariance (ANCOVA) was used to compare the mean percent monomethylarsonic acid (%MMA), dimethylarsonic acid (%DMA), inorganic arsenic (%iAs), primary methylation index (PMI, MMA/iAs), and secondary methylation index (SMI, DMA/MMA). Multivariate analysis of covariance (MANCOVA) was used to compare selected metal concentrations. Mean %MMA was significantly lower and SMI was significantly higher in toenails from prostate cancer cases compared to controls in unadjusted and adjusted models. Proportions of arsenic species were correlated with total arsenic in toenails. Arsenic speciation in urine was not different between cases and controls, nor were metallome profiles in toenails and urine. Our results indicate that toenails are a viable biomarker for altered arsenic speciation in prostate cancer cases and may have greater utility than urine in this context.

The BC Generations Project as a tumor tissue resource for cancer research

e22512

Background: Population-based cohort studies can be a resource for tumor specimens, annotated with demographic, lifestyle, and health history data, that support innovative studies of cancer. These data are increasingly important for clinical studies as they can be useful predictors of prognosis and treatment response (1,2) Our aim was to establish and test a process for accessing tumor samples, held at pathology laboratories around British Columbia (BC), for participants of the BC Generations Project (BCGP). Methods: Through the BC Cancer Registry, pathology reports linked with each BCGP solid cancer case were manually reviewed to extract information (e.g., location of pathology laboratory, sample type (i.e., biopsy or excision), and accession number) needed to request tumor samples. From among the successfully abstracted pathology reports, we randomly selected a total of 200 breast, lung, bladder, and pancreatic cancer cases for which to attempt retrieval of formalin-fixed, paraffin-embedded (FFPE) blocks from pathology laboratories across BC. We selected these cancer sites as they capture a representative range of cancer characteristics (e.g., tumor sizes) with which to evaluate the effectiveness of our access process. Results: We successfully identified pathology reports for 1,100 (93%) of the 1,180 incident solid cancer cases diagnosed in BCGP as of 2019 and we successfully retrieved 183 (92%) of the 200 FFPE that we requested from pathology laboratories. No important differences in retrieval rates by cancer site, sample location (Greater Vancouver vs. Outside Greater Vancouver), sample type (biopsy vs. excision) or year of diagnosis were identified. Conclusions: This linkage exercise demonstrates the tremendous potential for BCGP to serve as a population-based resource for highly annotated tumor tissue samples. A text mining solution recently implemented by the Registry will allow us to automate the process for data abstraction and should capture pathology reports for 100% of all newly diagnosed BCGP cancer cases moving forward. This will further enhance the utility of BCGP as a high-quality tumor tissue research resource. References: Lugo D, Pulido AL, Mihos CG, Issa O, Cusnir M, Horvath SA, Lin J, Santana O. The effects of physical activity on cancer prevention, treatment and prognosis: A review of the literature. Complement Ther Med 2019; 44:9–13. Peppone LJ, Mustian KM, Morrow GR, Dozier AM, Ossip DJ, Janelsins MC, Sprod LK, McIntosh S. The Effect of Cigarette Smoking on Cancer Treatment–Related Side Effects. The Oncologist 2011; 16:1784–92.

Evaluation of Adiposity and Cognitive Function in Adults

IMPORTANCE

Excess adipose tissue increases other cardiovascular risk factors, which may be associated with vascular brain injury and cognitive impairment. However, the extent to which the amount and distribution of adipose tissue may be associated with lower cognitive scores, independent of its association with cardiovascular risk factors, is not well characterized.

OBJECTIVE

To investigate the association of adiposity on vascular brain injury and cognitive scores.

DESIGN, SETTING, AND PARTICIPANTS

A total of 9189 participants from the Canadian Alliance for Healthy Hearts and Minds (CAHHM) and the Prospective Urban Rural Epidemiological-Mind (PURE-MIND) cohort studies were included in this cross-sectional analysis. Of these adults, 9166 underwent bioelectrical impedance analysis to assess body fat (BF) percentage, and 6773 underwent magnetic resonance imaging to assess vascular brain injury and measure visceral adipose tissue (VAT) volume. Participants from CAHHM were recruited from January 1, 2014, to December 31, 2018, and PURE-MIND participants were recruited from January 1, 2010, to December 31, 2018. Both CAHHM and PURE-MIND comprise multisite, population-based cohorts. Participants from CAHHM are from Canada, and PURE-MIND participants are from Canada or Poland. Data analysis was performed from May 3 to November 24, 2021.

EXPOSURES

The percentage of BF and VAT were modeled as sex-specific quartiles. Vascular brain injury was defined as high white matter hyperintensities or silent brain infarction. Multivariable mixed models were used to examine factors associated with reduced cognitive scores.

MAIN OUTCOMES AND MEASURES

Cognitive function was assessed using the Digital Symbol Substitution Test (DSST; scores range from 0 to 133, with lower scores indicating lower cognitive function) and Montreal Cognitive Assessment (scores range from 0 to 30, with a score of ≥26 denoting normal cognitive function). Reduced cognition was defined as a DSST score less than 1 SD below the mean. Cardiovascular risk was assessed using the INTERHEART Risk Score (IHRS; scores range from 0 to 48; low risk is defined as a score of 0 to 9, moderate risk as 10 to 16, and high risk as 17 or higher).

RESULTS

A total of 9189 adults (mean [SD] age, 57.8 [8.8] years; 5179 [56.4%] women; and 1013 [11.0%] East and Southeast Asian; 295 [3.2%] South Asian; 7702 [83.8%] White European; and 179 [1.9%] other, including Black, Indigenous, mixed, and unknown ethnicity) participated in the study. Visceral adipose tissue was highly correlated with body adiposity measured by BF percentage (r = 0.76 in women; r = 0.70 in men). Cardiovascular risk factors increased with increasing BF percentage with the fourth quartile IHRS at 13.8 (95% CI, 13.5-14.0; P < .001 for trend) and with VAT with the fourth quartile IHRS at 13.3 (95% CI, 13.0-13.5; P < .001 for trend). Vascular brain injury increased with increasing BF percentage with the fourth quartile value at 8.6% (95% CI, 7.5%-9.8%; P = .007 for trend) and with increasing VAT with fourth quartile value at 7.2% (95% CI, 6.0-8.4; P = .05 for trend). Cognitive scores were lower with increasing BF percentage with the fourth quartile score of 70.9 (95% CI, 70.4-71.5; P < .001 for trend) and for VAT with the fourth quartile score of 72.8 (95% CI, 72.1-73.4; P < .001 for trend). For every 1-SD increase in BF percentage (9.2%) or VAT (36 mL), the DSST score was lower by 0.8 points (95% CI, 0.4-1.1; P < .001) for BF percentage and lower by 0.8 points (95% CI, 0.4-1.2; P < .001) for VAT, adjusted for cardiovascular risk factors and vascular brain injury. The population attributable risk for reduced DSST score for higher BF percentage was 20.5% (95% CI, 7.0%-33.2%) and for VAT was 19.6% (95% CI, 2.0%-36.0%). Higher BF percentage and VAT were not associated with Montreal Cognitive Assessment scores.

CONCLUSIONS AND RELEVANCE

In this cross-sectional study, generalized and visceral adiposity were associated with reduced cognitive scores, after adjustment for cardiovascular risk factors, educational level, and vascular brain injury. These results suggest that strategies to prevent or reduce adiposity may preserve cognitive function.

Patterns and determinants of adherence to colorectal cancer primary and secondary prevention recommendations in the BC Generations Project

INTRODUCTION

Adherence to cancer prevention recommendations can greatly reduce colorectal cancer risk. This study explored patterns and determinants of adherence to these recommendations by participants (n = 26 074) at baseline in a cohort study in British Columbia, Canada.

METHODS

Adherence to five colorectal cancer primary prevention behaviours derived from Canadian Cancer Society/World Cancer Research Fund recommendations (nonsmoking, body mass index (BMI), physical activity, alcohol consumption and fruit and vegetable consumption) was measured, and a composite score constructed based on their sum. The definition of secondary prevention adherence was based on the Canadian Task Force on Preventive Health Care recommendations for colorectal cancer screening.

RESULTS

Adherence to primary prevention guidelines ranged from 94.8% (nonsmoking) to 44.2% (healthy BMI). Median composite score was 4. Higher composite scores were associated with being female, being married and with a higher educational attainment. Colorectal cancer screening adherence was 62.4%. Older age, chronic conditions, a recent medical examination and higher income were associated with greater odds of adherence to screening.

CONCLUSION

Adherence to some colorectal cancer prevention behaviours was high, consistent with findings that British Columbia has low rates of many risky health behaviours. However, there was a clustering of poorer adherence to prevention behaviours with each other and with other risk factors. Screening adherence was high but varied with some sociodemographic and health factors. Future work should evaluate targeted interventions to improve adherence among those in the lowest socioeconomic status and health groups. A better understanding is also needed of the barriers to access and engagement with colorectal cancer screening that persist even in the Canadian public health care system.

Normal sex and age-specific parameters in a multi-ethnic population: a cardiovascular magnetic resonance study of the Canadian Alliance for Healthy Hearts and Minds cohort

BACKGROUND

Despite the growing utility of cardiovascular magnetic resonance (CMR) for cardiac morphology and function, sex and age-specific normal reference values derived from large, multi-ethnic data sets are lacking. Furthermore, most available studies use a simplified tracing methodology. Using a large cohort of participants without history of cardiovascular disease (CVD) or risk factors from the Canadian Alliance for Healthy Heart and Minds, we sought to establish a robust set of reference values for ventricular and atrial parameters using an anatomically correct contouring method, and to determine the influence of age and sex on ventricular parameters.

METHODS AND RESULTS

Participants (n = 3206, 65% females; age 55.2 ± 8.4 years for females and 55.1 ± 8.8 years for men) underwent CMR using standard methods for quantitative measurements of cardiac parameters. Normal ventricular and atrial reference values are provided: (1) for males and females, (2) stratified by four age categories, and (3) for different races/ethnicities. Values are reported as absolute, indexed to body surface area, or height. Ventricular volumes and mass were significantly larger for males than females (p < 0.001). Ventricular ejection fraction was significantly diminished in males as compared to females (p < 0.001). Indexed left ventricular (LV) end-systolic, end-diastolic volumes, mass and right ventricular (RV) parameters significantly decreased as age increased for both sexes (p < 0.001). For females, but not men, mean LV and RVEF significantly increased with age (p < 0.001).

CONCLUSION

Using anatomically correct contouring methodology, we provide accurate sex and age-specific normal reference values for CMR parameters derived from the largest, multi-ethnic population free of CVD to date.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT02220582. Registered 20 August 2014-Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT02220582 .

Chronic disease and where you live: Built and natural environment relationships with physical activity, obesity, and diabetes

BACKGROUND

Diabetes is among the most prevalent non-communicable diseases causing significant morbidity and mortality globally. The aetiology and disease development of diabetes are influenced by genetic, lifestyle, and environmental factors. Due to an increasing number of cases each year, it is imperative to improve the understanding of modifiable environmental risk and protective factors. In this study we aimed to analyse associations between built and natural environment features and diabetes prevalence; and two major risk factors: physical activity and obesity and their mediation effects.

METHODS

We analysed relationships between walkability and park availability with physical activity, obesity, and diabetes, using self-reported data from a large cross-sectional survey in British Columbia, Canada (n = 22,418). We validated results with an independent cohort (n = 11,972) in a subset of the analyses. The outcome measures included walking, moderate to vigorous physical activity (MVPA), body mass index (BMI), and diabetes. Built and natural environment features within a 1 km road network buffer around residential postal code centroids were assessed using validated indicators of walkability and park availability. We used general linear multivariable models (GLM) to examine the direct relationship between environmental features, physical activity, obesity, and diabetes respectively. Path models were developed to analyse mediation effects of physical activity and obesity on the association between environmental indicators and diabetes. The relative contribution of direct versus indirect effects was assessed. All models were adjusted for age, gender, income. ethnicity, years lived in neighbourhood and regional accessibility.

RESULTS

Walkable neighbourhoods and areas with greater park availability were associated with lower rates of diabetes. There was a direct association of walkability and park availability on physical activity (highest vs. lowest quintile OR = 1.15; 95% CI: 1.00, 1.33 and OR = 1.28, 95% CI: 1.13, 1.45 respectively), obesity (highest vs. lowest quintile OR = 0.58, 95% CI: 0.49, 0.70 and OR = 0.57, 95% CI: 0.48, 0.68 respectively) and diabetes (highest vs. lowest quintile OR = 0.62, 95% CI: 0.45, 0.85, and OR = 0.63, 95% CI: 0.47, 0.84 respectively). Results were similar in the independent cohort. The associations between diabetes and walkability and park availability respectively were partly mediated by obesity (41% of total association for walkability and 53% of total association for park availability). The mediating effect of physical activity was negligible.

CONCLUSION

Results support investments in walkability through active transportation and transit infrastructure. Changes in zoning and subdivision regulations governing land use actions are required to enable compact mixed-use environments with access to parks and high quality transit service. Future studies including cost-benefit analyses of health-related economic impacts of such investments can contribute to evidence-based decisions for healthier cities.

Effect of Cognitive Reserve on the Association of Vascular Brain Injury With Cognition: Analysis of the PURE and CAHHM Studies

BACKGROUND AND OBJECTIVES

To determine whether cognitive reserve attenuates the association of vascular brain injury with cognition.

METHODS

Cross-sectional data were analyzed from 2 harmonized studies: the Canadian Alliance for Healthy Hearts and Healthy Minds (CAHHM) and the Prospective Urban and Rural Epidemiology (PURE) study. Markers of cognitive reserve were education, involvement in social activities, marital status, height, and leisure physical activity, which were combined into a composite score. Vascular brain injury was defined as nonlacunar brain infarcts or high white matter hyperintensity (WMH) burden on MRI. Cognition was assessed using the Montreal Cognitive Assessment Tool (MoCA) and the Digit Symbol Substitution Test (DSST).

RESULTS

There were 10,916 participants age 35-81. Mean age was 58.8 years (range 35-81) and 55.8% were female. Education, moderate leisure physical activity, being in a marital partnership, being taller, and participating in social groups were each independently associated with higher cognition, as was the composite cognitive reserve score. Vascular brain injury was associated with lower cognition (β -0.35 [95% confidence interval [CI] -0.53 to -0.17] for MoCA and β -2.19 [95% CI -3.22 to -1.15] for DSST) but the association was not modified by the composite cognitive reserve variable (interaction p = 0.59 for MoCA and p = 0.72 for DSST).

CONCLUSIONS

Both vascular brain injury and markers of cognitive reserve are associated with cognition. However, the effects were independent such that the adverse effects of covert vascular brain injury were not attenuated by higher cognitive reserve. To improve cognitive brain health, interventions to both prevent cerebrovascular disease and promote positive lifestyles are needed.

Community design and hypertension: Walkability and park access relationships with cardiovascular health

BACKGROUND

There is an increased literature focusing on the role of the built and natural environments in preventing hypertension. However, very few studies have quantitively analyzed specific pathways through which urban form affects blood pressure levels.

OBJECTIVES

To examine how features of the built and natural environments relate to hypertension and the mediating role of transportation and leisure walking and body mass index in this relationship.

METHODS

We examined the association between neighbourhood walkability and park availability with hypertension through generalized linear models in two independent population cohorts. One Cohort was 22,418 adults (My Health My Community) and the other cohort was 11,972 adults (BC Generations Project). We employed a path analysis modelling approach to explore the presence and significance of mediating factors that may contribute to any association between walkability or park availability and hypertension. This study intentionally employed walkability measures enforced through municipal zoning and subdivision regulations legally underpinned by health, safety, and welfare. All models were adjusted for socioeconomic and other characteristics where data were available.

RESULTS

Our analysis of two population-based Canadian cohorts consistently found that higher levels of walkability and park accessibility were both associated with significantly lower odds of self-reported hypertension, especially for lower income individuals. Mediation analysis showed that obesity accounted for 50% and 52.9% of the total effect of walkability and park accessibility on hypertension, respectively.

DISCUSSION

We suggest an integrated population health approach that considers multimorbidity as a result of exposure to car-dependent areas and the lack of green spaces. Longitudinal research is needed to document causal effects of built and natural environments on hypertension.

Cardiovascular risk scoring and magnetic resonance imaging detected subclinical cerebrovascular disease

Aims 

Cardiovascular risk factors are used for risk stratification in primary prevention. We sought to determine if simple cardiac risk scores are associated with magnetic resonance imaging (MRI)-detected subclinical cerebrovascular disease including carotid wall volume (CWV), carotid intraplaque haemorrhage (IPH), and silent brain infarction (SBI).

Methods and results

A total of 7594 adults with no history of cardiovascular disease (CVD) underwent risk factor assessment and a non-contrast enhanced MRI of the carotid arteries and brain using a standardized protocol in a population-based cohort recruited between 2014 and 2018. The non-lab-based INTERHEART risk score (IHRS) was calculated in all participants; the Framingham Risk Score was calculated in a subset who provided blood samples (n = 3889). The association between these risk scores and MRI measures of CWV, carotid IPH, and SBI was determined. The mean age of the cohort was 58 (8.9) years, 55% were women. Each 5-point increase (∼1 SD) in the IHRS was associated with a 9 mm³ increase in CWV, adjusted for sex (P < 0.0001), a 23% increase in IPH [95% confidence interval (CI) 9–38%], and a 32% (95% CI 20–45%) increase in SBI. These associations were consistent for lacunar and non-lacunar brain infarction. The Framingham Risk Score was also significantly associated with CWV, IPH, and SBI. CWV was additive and independent to the risk scores in its association with IPH and SBI.

Conclusion 

Simple cardiovascular risk scores are significantly associated with the presence of MRI-detected subclinical cerebrovascular disease, including CWV, IPH, and SBI in an adult population without known clinical CVD.

Childhood exposure to ionizing radiation from computed tomography imaging in Nova Scotia

BACKGROUND

Examining radiation dose in the paediatric population is particularly important due to the vulnerability of paediatric patients (increased radiosensitive tissues and postexposure life-years) and risk for future radiogenic malignancy.

OBJECTIVES

To evaluate trends in paediatric computed tomography (CT) use and ionizing radiation exposure using population-based data from Nova Scotia.

METHODS

A retrospective, population-based cohort study of CT use in patients <20 years of age, from January 1, 2004 to December 31, 2011, was performed in Nova Scotia. CT examination data were retrieved from a provincial imaging repository. Trends in CT use were described, and both annual and cumulative effective dose exposures were calculated.

RESULTS

In total, 29,452 CT events, involving up to 22,867 individuals were retrieved. Overall annual paediatric CT examination rates remained static (range 17.4 to 18.8 per 1000 per year). However, use in children <10 years of age decreased by >50% (P<0.001); this was counterbalanced by a steady increase among 15- to 19-year-olds (P<0.0001). Overall, 15.4% of scanned patients underwent ≥2 examinations, of which 58 patients (1.6%) exceeded 50 mSv of exposure.

CONCLUSIONS

Despite a static rate in CT imaging among the entire cohort, children <15 years of age and, particularly, those <10 years of age displayed marked reductions in CT use. This may reflect increased awareness of campaigns emphasizing judicious CT use, revised clinical practice guidelines and increased availability of alternative modalities. A small subgroup demonstrated high-dose exposure (>50 mSv), and rates in individuals >15 years of age steadily increased, suggesting further exposure reduction efforts are necessary.

Physical activity and nutrition among youth in rural, suburban and urban neighbourhood types

OBJECTIVES

Physical activity and nutrition are essential to healthy living and particularly important during youth, when growth and development are key. This study examined rates of physical activity (PA) and diet quality (DQ) among youth in grades 7 to 9 in Halifax, Nova Scotia, during the 2008/09 school year and tested differences among students in rural, urban and suburban neighbourhood types of high and low socio-economic status (SES).

METHODS

Youth in grades 7 through 9 (aged 12-16; 53% male) from six schools (N=380), stratified by neighbourhood type (urban, suburban, rural) and SES, wore accelerometers for up to 7 days (mean=4.14, standard deviation=1.49) and completed a nutritional survey.

RESULTS

The findings suggest important differences in PA and DQ across SES and neighbourhood type. Specifically, rates of moderate to vigorous physical activity among youth from schools in lower socio-economic areas were higher in urban than in suburban or rural settings. Furthermore, DQ was better among youth in higher than in lower socio-economic urban settings.

CONCLUSIONS

Understanding these differences in PA and DQ across rural, urban and suburban environments of high and low SES may highlight subgroups and targeted geographic areas for the design of interventions to improve rates of PA and health nutrition.

Physical activity and nutrition among youth in rural, suburban and urban neighbourhood types

OBJECTIVES

Physical activity and nutrition are essential to healthy living and particularly important during youth, when growth and development are key. This study examined rates of physical activity (PA) and diet quality (DQ) among youth in grades 7 to 9 in Halifax, Nova Scotia, during the 2008/09 school year and tested differences among students in rural, urban and suburban neighbourhood types of high and low socio-economic status (SES).

METHODS

Youth in grades 7 through 9 (aged 12-16; 53% male) from six schools (N=380), stratified by neighbourhood type (urban, suburban, rural) and SES, wore accelerometers for up to 7 days (mean=4.14, standard deviation=1.49) and completed a nutritional survey.

RESULTS

The findings suggest important differences in PA and DQ across SES and neighbourhood type. Specifically, rates of moderate to vigorous physical activity among youth from schools in lower socio-economic areas were higher in urban than in suburban or rural settings. Furthermore, DQ was better among youth in higher than in lower socio-economic urban settings.

CONCLUSIONS

Understanding these differences in PA and DQ across rural, urban and suburban environments of high and low SES may highlight subgroups and targeted geographic areas for the design of interventions to improve rates of PA and health nutrition.

A composite epidemic curve for seasonal influenza in Canada with an international comparison

BACKGROUND

Empirical data on laboratory-confirmed seasonal influenza is limited by very low and possibly non-systematic case ascertainment as well as geographical variation.

OBJECTIVE

To provide a visual representation of an influenza epidemic at the community and regional level using empirical data and to describe the epidemic characteristics.

METHODS

Weekly influenza A confirmations were obtained from the Canadian FluWatch program and American FluView program for the 1997/1998-2006/2007 seasons; 1- year data were also available for Europe (FluNet, WHO). For seasons where at least 80% of the influenza A strains were antigenically similar, a composite epidemic curve was created by centring the local epidemics relative to their epidemic midpoint.

RESULTS

The range in timing of the regional peaks varied from 5 to 13 weeks. Once the epidemic curves were centred relative to their peak, the composite epidemic curves were similar for Canada, the United States and Europe, and the epidemic growth rates were similar for most subgroups (city size; regions; H1N1 versus H3N2 seasons). During the exponential growth period, the number of cases increased by a factor of 1.5-2.0 per week, averaging 1.8. Exponential growth was evident approximately 10 weeks before the peak. Evidence of sustained transmission occurred from mid-September to early June.

DISCUSSION

The shape of the composite curve created in this study clearly demonstrates a consistency in the epidemic pattern across geographically disparate locales. Laboratory confirmation will likely play an increasing role in the development of better methods for early detection and summary measures of influenza activity.