Analytical performance of the FDA-cleared Parsortix® PC1 system.

Introduction: The Parsortix® PC1 system, Food and Drug Administration (FDA) cleared for use in metastatic breast cancer (MBC) patients, is an epitope-independent microfluidic device for the capture and harvest of circulating tumor cells from whole blood based on cell size and deformability. This report details the analytical characterization of linearity, detection limit, precision, and reproducibility for this device. Methods: System performance was determined using K2-EDTA blood samples collected from self-declared healthy female volunteers (HVs) and MBC patients spiked with prelabeled cultured breast cancer cell lines (SKBR3, MCF7, or Hs578T). Samples were processed on Parsortix® PC1 systems and captured cells were harvested and enumerated. Results: The system captured and harvested live SKBR3, MCF7, and Hs578T cells and fixed SKBR3 cells linearly between 2 and ~100 cells, with average harvest rates of 69%, 73%, 79%, and 90%, respectively. To harvest ≥1 cell ≥95% of the time, the system required 3, 5 or 4 live SKBR3, MCF7 or Hs578T cells, respectively. Average harvest rates from precision studies using 5, 10, and ~50 live cells spiked into blood for each cell line ranged from 63.5% to 76.2%, with repeatability and reproducibility percent coefficient of variation (%CV) estimates ranging from 12.3% to 32.4% and 13.3% to 34.1%, respectively. Average harvest rates using ~20 fixed SKBR3 cells spiked into HV and MBC patient blood samples were 75.0% ± 16.1% (%CV = 22.3%) and 68.4% ± 14.3% (%CV = 21.1%), respectively. Conclusions: These evaluations demonstrate the Parsortix® PC1 system linearly and reproducibly harvests tumor cells from blood over a range of 1 to ~100 cells.

Quantifying the contribution of modifiable risk factors to socio-economic inequities in cancer morbidity and mortality: a nationally representative population-based cohort study.

BACKGROUND: Compared with those with a higher socio-economic position (SEP), individuals with a lower SEP have higher cancer morbidity and mortality. However, the contribution of modifiable risk factors to these inequities is not known. This study aimed to quantify the mediating effects of modifiable risk factors to associations between SEP and cancer morbidity and mortality. METHODS: This study used a prospective observational cohort design. We combined eight cycles of the Canadian Community Health Survey (2000/2001-2011) as baseline data to identify a cohort of adults (≥35 years) without cancer at the time of survey administration (n = 309 800). The cohort was linked to the Discharge Abstract Database and the Canadian Mortality Database for cancer morbidity and mortality ascertainment. Individuals were followed from the date they completed the Canadian Community Health Survey until 31 March 2013. Dates of individual first hospitalizations for cancer and deaths due to cancer were captured during this time period. SEP was operationalized using a latent variable combining measures of education and household income. Self-reported modifiable risk factors, including smoking, excess alcohol consumption, low fruit-and-vegetable intake, physical inactivity and obesity, were considered as potential mediators. Generalized structural equation modelling was used to estimate the mediating effects of modifiable risk factors in associations between low SEP and cancer morbidity and mortality in the total population and stratified by sex. RESULTS: Modifiable risk factors together explained 45.6% of associations between low SEP and overall cancer morbidity and mortality. Smoking was the most important mediator in the total population and for males, accounting for 15.5% and 40.2% of the total effect, respectively. For females, obesity was the most important mediator. CONCLUSIONS: Modifiable risk factors are important mediators of socio-economic inequities in cancer morbidity and mortality. Nevertheless, more than half of the variance in these associations remained unexplained. Midstream interventions that target modifiable risk factors may help to alleviate inequities in cancer risk in the short term. However, ultimately, upstream interventions that target structural determinants of health are needed to reduce overall socio-economic inequities in cancer morbidity and mortality.

The association of household food security, household characteristics and school environment with obesity status among off-reserve First Nations and Métis children and youth in Canada: results from the 2012 Aboriginal Peoples Survey. / Relation entre l'obésité et la sécurité alimentaire des ménages, les caractéristiques des ménages et le milieu scolaire chez les enfants métis et des Premières Nations vivant hors réserve au Canada : résultats de l'Enquête auprès des peuples autochtones de 2012.

INTRODUCTION: Indigenous children are twice as likely to be classified as obese and three times as likely to experience household food insecurity when compared with non- Indigenous Canadian children. The purpose of this study was to explore the relationship between food insecurity and weight status among Métis and off-reserve First Nations children and youth across Canada. METHODS: We obtained data on children and youth aged 6 to 17 years (n = 6900) from the 2012 Aboriginal Peoples Survey. We tested bivariate relationships using Pearson chi-square tests and used nested binary logistic regressions to examine the food insecurity-weight status relationship, after controlling for geography, household and school characteristics and cultural factors. RESULTS: Approximately 22% of Métis and First Nations children and youth were overweight, and 15% were classified as obese. Over 80% of the sample was reported as food secure, 9% experienced low food security and 7% were severely food insecure. Off-reserve Indigenous children and youth from households with very low food security were at higher risk of overweight or obese status; however, this excess risk was not independent of household socioeconomic status, and was reduced by controlling for household income, adjusted for household size. Negative school environment was also a significant predictor of obesity risk, independent of demographic, household and geographic factors. CONCLUSION: Both food insecurity and obesity were prevalent among the Indigenous groups studied, and our results suggest that a large proportion of children and youth who are food insecure are also overweight or obese. This study reinforces the importance of including social determinants of health, such as income, school environment and geography, in programs or policies targeting child obesity.

INTRODUCTION: Les enfants autochtones sont deux fois plus susceptibles d'être classés comme obèses et trois fois plus susceptibles de vivre dans l'insécurité alimentaire que les autres enfants canadiens. Le but de cette étude est d'explorer la relation entre l'insécurité alimentaire et le poids chez les enfants et les jeunes métis et des Premières Nations vivant hors réserve à l'échelle du Canada. MÉTHODOLOGIE: Nous avons obtenu des données sur les enfants et les jeunes de 6 à 17 ans (n = 6 900) tirées de l'Enquête auprès des peuples autochtones de 2012. Nous avons testé les relations bivariées à l'aide des tests du chi carré de Pearson et utilisé des régressions logistiques binaires imbriquées pour examiner la relation entre l'insécurité alimentaire et le poids, en tenant compte de la dimension spatiale, des caractéristiques des ménages ainsi que de l'environnement scolaire et de facteurs culturels. RÉSULTATS: Environ 22 % des enfants et des jeunes métis et des Premières Nations souffraient d'embonpoint et 15 % étaient classés comme obèses. Plus de 80 % des répondants ont signalé ne pas souffrir d'insécurité alimentaire, 9 % ont fait état d'une sécurité alimentaire faible et 7 % d'insécurité alimentaire grave. Les enfants et les jeunes autochtones vivant hors réserve dans des ménages à très faible sécurité alimentaire présentaient un risque accru d'embonpoint ou d'obésité, quoique ce risque accru ne se soit pas révélé indépendant du statut socioéconomique du ménage et qu'il se soit trouvé réduit en tenant compte du revenu du ménage après ajustement en fonction de la taille de ce dernier. Un environnement scolaire négatif s'est révélé également être un prédicteur important du risque d'obésité, indépendamment des facteurs démographiques, spatiaux et liés aux ménages. CONCLUSION: L'insécurité alimentaire et l'obésité étaient répandues parmi les groupes autochtones étudiés, et nos résultats laissent penser que les enfants et les jeunes en situation d'insécurité alimentaire souffrent également en grande proportion d'embonpoint ou d'obésité. Cette étude renforce l'importance d'inclure les déterminants sociaux de la santé tels que le revenu, l'environnement scolaire et la dimension spatiale dans les programmes ou les politiques ciblant l'obésité infantile.

A cross-sectional examination of the correlates of current smoking among off-reserve First Nations and Métis adults: Evidence from the 2012 Aboriginal Peoples Survey.

INTRODUCTION: The purpose of this study was to examine the correlates of current smoking among off-reserve First Nations and Métis adults, two Aboriginal Canadian groups that are at higher risk to smoke and more likely to suffer from chronic health conditions relative to their non-Aboriginal counterparts. A particular focus was on culturally specific factors and their associations with current smoking. METHODS: We used data from Statistics Canada's, 2012 Aboriginal Peoples Survey to investigate the correlates of smoking among 12,720 First Nations and Métis adults. Sequential binary logistic regression models were estimated to examine associations between smoking and culturally specific, demographic, geographic, socioeconomic and health-related variables. RESULTS: Overall, 39.4% were current smokers. Multivariate results found that those who had hunted, fished or trapped within the last year were more likely to be smokers. In addition, respondents who were exposed to an Aboriginal language at home or outside the home were more likely to be smokers. Current smoking was significantly associated with being aged 35 to 49 years, living in a small population center, low income, low education, unemployment, being unmarried, low ratings of self-perceived health, heavy drinking and low body mass index. Respondents aged 65 years and older and those living in British Columbia were less likely to smoke. DISCUSSION: The results of this study suggest that it may be useful to consider cultural characteristics, particularly language in efforts to reduce the prevalence of manufactured tobacco use among First Nations and Métis adults. Interventions should also consider demographic, geographic and socioeconomic variables, in addition to co-occurring health-risk behaviors.

Community perspectives on food insecurity and obesity: Focus groups with caregivers of metis and Off-reserve first nations children.

INTRODUCTION: Aboriginal children in Canada are at a higher risk for overweight and obesity than other Canadian children. In Northern and remote areas, this has been linked to a lack of affordable nutritious food. However, the majority of Aboriginal children live in urban areas where food choices are more plentiful. This study aimed to explore the experiences of food insecurity among Métis and First Nations parents living in urban areas, including the predictors and perceived connections between food insecurity and obesity among Aboriginal children. METHODS: Factors influencing children's diets, families' experiences with food insecurity, and coping strategies were explored using focus group discussions with 32 parents and caregivers of Métis and off-reserve First Nations children from Midland-Penetanguishene and London, Ontario. Four focus groups were conducted and transcribed verbatim between July 2011 and March 2013. A thematic analysis was conducted using NVivo software, and second coders ensured reliability of the results. RESULTS: Caregivers identified low income as an underlying cause of food insecurity within their communities and as contributing to poor nutrition among their children. Families reported a reliance on energy-dense, nutrient-poor foods, as these tended to be more affordable and lasted longer than more nutritious, fresh food options. A lack of transportation also compromised families' ability to purchase healthful food. Aboriginal caregivers also mentioned a lack of access to traditional foods. Coping strategies such as food banks and community programming were not always seen as effective. In fact, some were reported as potentially exacerbating the problem of overweight and obesity among First Nations and Métis children. CONCLUSION: Food insecurity manifested itself in different ways, and coping strategies were often insufficient for addressing the lack of fruit and vegetable consumption in Aboriginal children's diets. Results suggest that obesity prevention strategies should take a family-targeted approach that considers the unique barriers facing urban Aboriginal populations. This study also reinforces the importance of low income as an important risk factor for obesity among Aboriginal peoples.

The correlates of current smoking among adult Métis: Evidence from the Aboriginal Peoples Survey and Métis Supplement.

OBJECTIVE: To examine the correlates of current smoking among Métis aged 18 years and older, with a particular focus on culturally-specific factors. Cultural factors included spirituality, knowledge of an Aboriginal language, membership in a Métis organization and attendance at Métis cultural events. Demographic, geographic, socio-economic and health-related variables were also considered. METHODS: Data from 6,610 adult Métis aged 18 years and older who responded to the 2006 Aboriginal Peoples Survey and Métis supplement were used to examine the correlates of current smoking using sequential binary logistic regression modelling. RESULTS: Overall, 39.9% of adult Métis respondents in the sample were current smokers. Adult Métis who reported a high level of spirituality were less likely to be current smokers. Those who spoke an Aboriginal language, or lived in a house where an Aboriginal language was spoken, were more likely to be current smokers. Being a member of a Métis organization and attending cultural events were not independently associated with current smoking. Métis with higher household income, greater education, higher self-perceived health, and greater physical activity participation were less likely to be current smokers, whereas those who reported heavy alcohol consumption were more likely to be current smokers. CONCLUSIONS: The results of this study suggest that interventions aimed at reducing smoking among adult Métis might be more successful if they include some connection to spirituality. It is also evident that co-occurring risk behaviours, in addition to demographic and socio-economic factors, are important considerations when developing interventions to reduce smoking among this population.

Predictors of obesity among Métis children: socio-economic, behavioural and cultural factors.

OBJECTIVES: To examine the socio-economic, behavioural and Métis-specific factors that predict obesity among Métis children aged 6 to 14 years. Socio-economic factors included household structure and income, parental education and food insecurity. Cultural factors included knowledge of an Aboriginal language, participation in cultural activities, time spent with Elders and parental residential school attendance. METHODS: The 2006 Aboriginal Peoples Survey, Children and Youth component collected data about Métis children, including child height and weight, reported by the person most knowledgeable about the child (PMK). Multivariate binary logistic regression was used to predict obesity, defined using IOTF BMI cut-offs. After testing for interactions, models were stratified by age (6-10, 11-14) and gender. RESULTS: An estimated 18.5% of Métis boys and 14.4% of girls were obese. The effects of socio-economic factors and region varied across age and gender groups, although living in a lone-parent family and rural residence had consistent effects. Many effects of cultural variables were unexpected. Although PMK residential schooling was positively associated with obesity generally, the effects were negative among older girls. As expected, children participating in frequent physical activity generally had lower risk, independent of other factors. CONCLUSIONS: Although socio-economic factors are related to risk of obesity among Métis children, the effects may not be the same across age groups and for boys and girls. There is some evidence of independent effects of Métis-specific cultural factors, including parental residential schooling, on the risk of child obesity, but further investigation and better data are needed to understand these relationships.