Mechanisms accounting for gendered differences in mental health status among young Canadians: A novel quantitative analysis.

Adolescent girls consistently report worse mental health than boys. This study used reports from a 2018 national health promotion survey (n = 11,373) to quantitatively explore why such gender-based differences exist among young Canadians. Using mediation analyses and contemporary social theory, we explored mechanisms that may explain differences in mental health between adolescents who identify as boys versus girls. The potential mediators tested were social supports within family and friends, engagement in addictive social media use, and overt risk-taking. Analyses were performed with the full sample and in specific high-risk groups, such as adolescents who report lower family affluence. Higher levels of addictive social media use and lower perceived levels of family support among girls mediated a significant proportion of the difference between boys and girls for each of the three mental health outcomes (depressive symptoms, frequent health complaints, and diagnosis of mental illness). Observed mediation effects were similar in high-risk subgroups; however, among those with low affluence, effects of family support were somewhat more pronounced. Study findings point to deeper, root causes of gender-based mental health inequalities that emerge during childhood. Interventions designed to reduce girls' addictive social media use or increase their perceived family support, to be more in line with their male peers, could help to reduce differences in mental health between boys and girls. Contemporary focus on social media use and social supports among girls, especially those with low affluence, warrant study as the basis for public health and clinical interventions.

A novel application of a data mining technique to study intersections in the social determinants of mental health among young Canadians.

OBJECTIVES: Adolescent mental health is an emergent clinical and public health priority in Canada. Gender-based differences in mental health are well established. The objective of this study was to evaluate a new data mining technique to identify social locations of young Canadians where differences in mental health between adolescent males and females were most pronounced. METHODS: We examined reports from 21,221 young Canadians aged 11-15 years (10,349 males, 10,872 females) who had responded to a 2018 national health and health behaviours survey. Using recursive partitioning for subgroup identification (SIDES), we identified social locations that were associated with the strongest differences between males and females for three reported mental health outcomes: positive psychosomatic health, symptoms of depression, and having a diagnosed mental illness. RESULTS: The SIDES algorithm identified both established and new intersections of social factors that were associated with gender-based differences in mental health experiences, most favouring males. DISCUSSION: This analysis represents a novel proof-of-concept to demonstrate the utility of a subgroup identification algorithm to reveal important differences in mental health experiences between adolescent males and females. The algorithm detected new social locations (i.e., where gender intersected with other characteristics) associated with poor mental health outcomes. These findings set the stage for further intersectional research, involving both quantitative and qualitative analyses, to explore how axes of discrimination may intersect to shape potential gender-based health inequalities that emerge during childhood.

Imputing accelerometer nonwear time in children influences estimates of sedentary time and its associations with cardiometabolic risk.

BACKGROUND: A limitation of measuring sedentary time with an accelerometer is device removal. The resulting nonwear time is typically deleted from the data prior to calculating sedentary time. This could impact estimates of sedentary time and its associations with health indicators. We evaluated whether using multiple imputation to replace nonwear accelerometer epochs influences such estimates in children. METHODS: 452 children (50% male) aged 10-13 were tasked with wearing an accelerometer (15 s epochs) for 7 days. On average, 8% of waking time was classified as nonwear time. Sedentary time was derived from a "nonimputed" dataset using the typical approach of deleting epochs that occurred during nonwear time, as well as from an "imputed" dataset. In the imputed dataset, each nonwear epoch was re-classified as being as sedentary or not using multiple imputation (5 iterations) which was informed by the likelihood of a wear time epoch being classified as sedentary or not using parameter estimates from a logistic regression model. Estimates of sedentary time and associations between sedentary time and health indicators (cardiometabolic risk factor and internalizing mental health symptoms Z-scores) were compared between the nonimputed and imputed datasets. RESULTS: On average, sedentary time was 33 min/day higher in the imputed dataset than in the nonimputed dataset (632 vs. 599 min/day). The association between sedentary time and the cardiometabolic risk factor Z-score was stronger in the imputed vs. the nonimputed dataset (ß = 0.137 vs. ß = 0.092 per 60 min/day change, respectively). These findings were more pronounced among children who had < 7 days with ≥10 h of wear time. CONCLUSION: Researchers should consider using multiple imputation to address accelerometer nonwear time, rather than deleting it, in order to derive more unbiased estimates of sedentary time and its associations with health indicators.

Masking in reports of "most serious" events: bias in estimators of sports injury incidence in Canadian children. / Le phénomène du masquage dans le signalement des événements « les plus graves ¼ : biais influant sur les estimations des taux d'incidence des blessures sportives chez les enfants canadiens.

INTRODUCTION: Surveys that collect information on injuries often focus on the single "most serious" event to help limit recall error and reduce survey length. However, this can mask less serious injuries and result in biased incidence estimates for specific injury subcategories. METHODS: Data from the 2002 Health Behaviour in School-aged Children (HBSC) survey and from the Canadian Hospitals Injury Reporting and Prevention Program (CHIRPP) were used to compare estimates of sports injury incidence in Canadian children. RESULTS: HBSC data indicate that 6.7% of children report sustaining a sports injury that required an emergency department (ED) visit. However, details were only collected on a child's "most serious" injury, so children who had multiple injuries requiring an ED visit may have had sports injuries that went unreported. The rate of 6.7% can be seen to be an underestimate by as much as 4.3%. Corresponding CHIRPP surveillance data indicate an incidence of 9.9%. Potential masking bias is also highlighted in our analysis of injuries attended by other health care providers. CONCLUSION: The "one most serious injury" line of questioning induces potentially substantial masking bias in the estimation of sports injury incidence, which limits researchers' ability to quantify the burden of sports injury. Longer survey recall periods naturally lead to greater masking. The design of future surveys should take these issues into account. In order to accurately inform policy decisions and the direction of future research, researchers must be aware of these limitations.

INTRODUCTION: Les enquêtes sur la cueillette de données sur les blessures ciblent souvent « l'événement le plus grave ¼ dans le but de limiter les erreurs de mémoire et de réduire la longueur des questionnaires. Cela risque cependant de masquer des blessures moins graves et d'entraîner un biais dans les estimations des taux d'incidence de certaines sous-catégories de traumatismes. MÉTHODOLOGIE: Nous avons utilisé des données tirées de l'Enquête sur les comportements liés à la santé des enfants d'âge scolaire (ECSEAS) et du Système canadien hospitalier d'information et de recherche en prévention des traumatismes (SCHIRPT) pour comparer les estimations des taux d'incidence des blessures sportives chez les enfants canadiens. RÉSULTATS: D'après les données de l'ECSEAS, 6,7 % des enfants déclarent avoir subi une blessure sportive ayant nécessité une consultation à un service des urgences. N'ont cependant été recueillies que les données sur la blessure « la plus grave ¼ subie par l'enfant, ce qui fait qu'un enfant ayant subi de multiples blessures justifiant une consultation à un service des urgences est susceptible d'avoir subi des blessures sportives passées sous silence. La sous-estimation de ce taux de 6,7 % pourrait atteindre 4,3 %. D'après les données de surveillance du SCHIRPT correspondantes, le taux d'incidence de ces blessures est de 9,9 %. Nous mettons également en lumière dans notre analyse le biais potentiel de masquage lié aux blessures traitées par d'autres prestataires de soins de santé. CONCLUSION: Poser une question sur « la blessure la plus grave ¼ risque d'induire un biais de masquage considérable du taux d'incidence des blessures sportives, limitant ainsi la capacité des chercheurs à estimer l'ampleur réelle du phénomène. Des périodes de rappel plus longues entraînent inévitablement un phénomène de masquage plus important. La conception des enquêtes à venir devrait tenir compte de ces réalités. Si l'on veut faciliter une prise de décisions éclairées et orienter correctement les futures recherches, il faut que les chercheurs soient conscients de ces limitations.

Toll like receptor-4 expression in lipopolysaccharide induced lung inflammation.

Bacterial lipopolysaccharides (LPS) initiate immune response through Toll-like receptor 4 (TLR4). Because many a times host is confronted with secondary bacterial challenges, it is critical to understand TLR4 expression following initial provocation. We studied TLR4 expression in rats at various times after intra-tracheal instillation of LPS. Although TLR4 mRNA was undetectable in normal lungs, it increased at 6h and 12h and declined at 36h post-LPS treatment. Western blots showed TLR4 protein at all time points. Immunohistochemistry localized TLR4 in alveolar septal cells, bronchial epithelium, macrophages and endothelium of large and peribronchial blood vessels. Dual label immunoelectron microscopy showed co-localization of TLR4 and LPS in the cytoplasm and nucleus of various lung and inflammatory cells. Nuclear localization of TLR4 was confirmed with Western blots on lung nuclear extracts. We conclude that TLR4 expression in lung is sustained up to 36 hours and that TLR4 and LPS are localized in the cytoplasm and nuclei of lung cells.

Experimental infection of emus (Dromaiius novaehollandiae) with avian influenza viruses of varying virulence: clinical signs, virus shedding and serology.

Two groups of emus were experimentally inoculated with a low and high pathogenic strain of avian influenza virus (AIV), type A to determine the virus susceptibility, pathogenicity, shedding and seroconversion. Emus were found susceptible to infection with AIV, with virus shedding detectable in tracheal and cloacal swabs between 3 and 10 days post-infection. Only the birds infected with the highly pathogenic viral isolate showed a brief period of mild clinical signs associated with infection. Virus recovered from the infected emus was found to be of similar pathogenicity to that of the virus inoculum. All the birds seroconverted by 10 days post-infection, as determined by haemagglutination inhibition, agar gel immunodiffusion and competitive ELISA assays. This study suggests that emus are similar to wild waterfowl in their response to AIV infection, in that they are susceptible and will replicate and shed the virus, but do not show any marked clinical signs of infection.

Evaluation of antibody responses of emus (Dromaius novaehollandiae) to avian influenza virus infection.

Emu antibody responses to avian influenza virus (AIV) infection were evaluated by the competitive enzyme-linked immunosorbent assay (C-ELISA), agar gel immunodiffusion (AGID) and hemagglutination inhibition (HI) tests. All birds infected with AIV H5N1, H5N3, or H7N7 developed antinucleoprotein (NP) antibodies as early as 7 days postinfection as detected by the C-ELISA. The responses lasted 49 days for the emus receiving H5N3 and at least 56 days for emus receiving the other two viruses. By evaluating 50 emu field serum samples, the C-ELISA was found more sensitive than the AGID test for the detection of anti-NP antibodies. This study indicates that emus experimentally infected with AIV developed antibody responses that can be detected by C-ELISA, AGID, and HI tests. The results from this and our previous studies demonstrate the use of the C-ELISA as a substitute for the AGID test in a routine serodiagnostic screening for detection of antibodies to AIV infection in multiple avian species.