BackgroundAir pollution in Beijing, especially PM2.5, has received increasing attention in the past years. Although exposure to PM2.5 has been linked to many health issues, few studies have quantified the impact of PM2.5 on the risk of influenza-like illness (ILI). The aim of our study is to investigate the association between daily PM2.5 and ILI risk in Beijing, by means of a generalized additive model.MethodsDaily PM2.5, meteorological factors, and influenza-like illness (ILI) counts during January 1, 2008 to December 31, 2014 were retrieved. An inverse Gaussian generalized additive model with log link function was used to flexibly model the nonlinear relationship between the PM2.5 (single- and multiday lagged exposure) and ILI risk, adjusted for the weather conditions, seasonal and year trends. We also assessed if the effect of PM2.5 differs during flu season versus non-flu season by including the interaction term between PM2.5 and flu season in the model. Furthermore, a stratified analysis by age groups was conducted to investigate how the effect of PM2.5 differs across age groups.ResultsOur findings suggested a strong positive relationships between PM2.5 and ILI risk at the flu season (October-April) (p-value < 0.001), after adjusting for the effects of ambient daily temperature and humidity, month and year; whereas no significant association was identified at the non-flu season (May-September) (p-value = 0.174). A short term delayed effect of PM2.5 was also identified with 2-day moving average (current day to the previous day) of PM2.5 yielding the best predictive power. Furthermore, PM2.5 was strongly associated with ILI risk across all age groups (p-value < 0.001) at the flu season, but the effect was the most pronounced among adults (age 25–59), followed by young adults (age 15–24), school children (age 5–14) and the elderly (age 60+) and the effect of PM2.5 was the least pronounced for children under 5 years of age (age < 5).ConclusionsAmbient PM2.5 concentrations were significantly associated with ILI risk in Beijing at the flu season and the effect of PM2.5 differed across age groups, in Beijing, China.

BackgroundRefugee women are almost five times more likely to develop postpartum depression than Canadian-born women. This can be attributed to various difficulties they faced before coming to Canada as well as during resettlement. Moreover, refugee women usually face many obstacles when accessing health services, including language and cultural barriers, as well as unique help-seeking behaviors that are influenced by various cultural and practical factors. There has been a recent, rapid influx of Syrian refugees to Canada, and many of them are childbearing women. However, little is known about the experiences that these women have encountered pre- and post-resettlement, and their perceptions of mental health issues. Thus, there is an urgent need to understand refugee women’s experiences of having a baby in Canada from a mental health perspective.MethodsA mixed methods research design included 12 Syrian refugee women who migrated to Saskatoon in 2015–16 and who were either pregnant or 1 year postpartum. The data were collected during a single focus group discussion and a structured questionnaire.ResultsOur results showed that more than half of participants have depressive symptoms, half of them have anxiety symptoms, and one sixth have PTSD symptoms. Three major themes emerged from the qualitative data: 1) Understanding of maternal depression; 2) Protective factors for mental health; and 3) Barriers to mental health services.ConclusionsMaternal depression is an important feature in Syrian refugee women recently resettled in Canada. Reuniting these women with their families and engaging them in culturally appropriate support programs may improve their mental health outcomes.Electronic supplementary materialThe online version of this article (doi:10.1186/s12884-017-1433-2) contains supplementary material, which is available to authorized users.

Background Many women still deliver outside a health facility in Ghana, often under unhygienic conditions and without skilled birth attendants. This study aims to examine the social determinants influencing the use of health facility delivery among reproductive-aged women in Ghana. Methods Nationally representative data from the 2014 Ghana Demographic and Health Survey was used to fit univariable and multivariable logistic regression models to estimate the influence of the social determinants on health facility delivery. Andresen’s health care utilization model was used as the conceptual framework guiding this study.. Results Only 72% of deliveries take place at a health facility in Ghana. The results of the adjusted model indicate that place of residence, financial status, education, religion, parity and perceived need were significantly associated with health facility delivery. First, urban women had a higher likelihood of health facility delivery than rural women (Adjusted Odds ratio [AOR] =2.21; 95% Confidence interval [CI] = 1.53–3.19). Second, middle-class and rich women were 1.57 (95%CI = 1.18–2.08) times and 6.91 (95%CI = 4.12–11.59) times, respectively more likely to deliver at health facility compared to the poor. Third, women with either at least secondary education (AOR = 2.04; 95%CI = 1.57–2.64) or primary education (AOR = 1.39, 95%CI = 1.02–1.92) were more likely to deliver at health facility than women with no education. In terms of parity, first time mothers were 1.58 (95% CI = 1.18–2.12) times more likely to deliver at health facility than those who had given birth three or more times before. Finally, regarding perceived need, women who were aware of pregnancy complications were 1.32 (95%CI = 1.02–1.70) times more likely to use health facility delivery than those who were not informed about pregnancy complications. Conclusions First, in spite of Ghana’s free maternal health services policy, poorer women were much less likely to have a health facility delivery, which points to the need to understand the indirect costs and other financial barriers preventing women from delivering at a health facility. Second, many of the identified variables influence the demand and not just the supply for health care services, and highlight the importance of the social determinants of health and investments in interventions that extend beyond improving physical access.

Purpose This longitudinal study examines the association between homelessness and injection drug use initiation among a cohort of street-involved youth in a setting of high prevalence crystal methamphetamine use. Methods Data were derived from the At-Risk Youth Study, a prospective cohort of street-involved youth aged 14 to 26 recruited between September 2005 and November 2011. Cox proportional hazards regression was used to identify factors independently associated with time to injection initiation. Results Among 422 street-youth who had never injected at baseline, 77 injection initiation events were observed during follow-up. Homelessness was independently associated with injection initiation in multivariate Cox regression (Relative Hazard: 1.80 [95% CI: 1.13–2.87]) after adjusting for crystal methamphetamine use and other potential confounders. Conclusions These findings highlight that homelessness is a key risk factor for injection initiation among street-involved youth. Supportive housing interventions for street-youth may help prevent injection drug use initiation among this high-risk population.

BackgroundMaternal depression and anxiety have distinct constellations of symptom trajectories, which are associated with factors that may vary between different groups of women. The aim of this study was to identify subgroups of women who exhibit unique longitudinal trajectory patterns of depressive and anxiety symptoms from pregnancy to 5 years postpartum and the antenatal predictors associated with these maternal groups.MethodsThe study used a longitudinal data collected from 615 women in Saskatchewan from pregnancy to 5 years postpartum. Semiparametric group-based models were used to identify latent maternal depressive and anxiety trajectory groups. Multinomial logit models were then used to assess the association between maternal characteristics and the identified latent trajectory groups.ResultsWe identified four trajectory groups of maternal depressive symptoms: low-stable (35%); moderate-stable (54%); moderate-increasing (5%); and high-decreasing (6%), and three trajectory groups of maternal anxiety symptoms: very low-stable (13%); low-stable (58%); and moderate-stable (29%). We also identified several risk factors, most notably history of depression and stress, that were significantly associated with these trajectories.ConclusionHistory of depression and increased stress are significant risk factors that can be identified during regular perinatal visits; therefore, clinicians should inquire about these risk factors to identify women at high risk of ongoing depression or anxiety.Electronic supplementary materialThe online version of this article (10.1186/s12884-019-2177-y) contains supplementary material, which is available to authorized users.

Despite evidence globally of the heavy HIV burden among sex workers (SWs), as well as other poor health outcomes, including violence, SWs are often excluded from accessing voluntary, confidential and non-coercive health services, including HIV prevention, treatment, care and support. This study therefore assessed the prevalence and associations with regular HIV testing among street- and off-street sex workers (SWs) in Vancouver, Canada. Cross-sectional baseline data were used from a longitudinal cohort known as ‘An Evaluation of Sex Worker's Health Access’ (‘AESHA’) (January 2010-July 2012). This cohort included youth and adult sex workers (14 years+). We used multivariable logistic regression to assess the relationship between explanatory variables and having a recent HIV test (in the last year). Of the 435 sero-negative SWs included, 67.1% reported having a recent HIV test. In multivariable logistic regression analysis, having a recent HIV test remained significantly independently associated with elevated odds of inconsistent condom use with clients (AOR: 2.59, 95%CIs: 1.17-5.78), injecting drugs (AOR: 2.33, 95%CIs: 1.17-4.18) and contact with a mobile HIV prevention program (AOR: 1.76, 95%CIs: 1.09-2.84) within the last six months. Reduced odds of having a recent HIV test was also significantly associated with being a migrant/new immigrant to Canada (AOR: 0.33, 95%CIs: 0.19-0.56) and having a language barrier to health care access (AOR: 0.26, 95%CIs: 0.09-0.73). Our results highlight successes of reaching SWs at high risk for HIV through drug and sexual pathways. To maximize the effectiveness of including HIV testing as part of comprehensive HIV prevention and care to SWs, increased mobile outreach and safer-environment interventions that facilitate access to voluntary, confidential and non-coercive HIV testing remain a critical priority, in addition to culturally safe services with language support.

BackgroundFalls pose major health problems to the middle-aged and older adults and may potentially lead to various levels of injuries. Sleep duration and disturbances have been shown to be associated with falls in literature; however, studies of the joint and distinct effects of those sleep problems are still sparse. To fill this gap, we aimed to determine the association between sleep duration, sleep disturbances and falls among middle-aged and older adults in China controlling for psychosocial, lifestyle, socio-demographical factors and comorbidity.MethodsData were derived from the China Health and Retirement Longitudinal Study (CHARLS) based on multi-stage sampling designs, with respondents aged 50 and older. Associations were evaluated by using multiple logistic regression adjusting for confounders and complex survey design. To further determine if the association of sleep duration/disturbance and falls depends on age groups, the study data were divided into two samples (age 50–64 vs. age 65+) and comparison was made between the two age groups.ResultsOf the 12,759 respondents, 2172 (17%) had falls within the last 2 years. Our findings indicated that the participants who had nighttime sleep duration ≤5 were more likely to report falls than those who had nighttime sleep duration ≥6 h; whereas no association between nighttime sleep duration > 8 h and falls. Participants having sleep disturbances 1–2 days, or 3–4 days, and 5–7 days per week were also more likely to report falls than those who had no sleep disturbance. The nap sleep duration was not significantly associated with falls. Although the combined sample found both sleep duration and sleep disturbance to be strongly associated with falls after adjusting for various confounders, sleep disturbance was not significantly related to falls among participants aged 65 + .ConclusionsOur study suggested that there is an independent association between falls and short sleep duration and disturbed sleep among middle-aged and older adults in China. Findings underscore the need for evidence-based prevention and interventions targeting sleep duration and disturbance among this study population.

Counts data with excessive zeros are frequently encountered in practice. For example, the number of health services visits often includes many zeros representing the patients with no utilization during a follow-up time. A common feature of this type of data is that the count measure tends to have excessive zero beyond a common count distribution can accommodate, such as Poisson or negative binomial. Zero-inflated or hurdle models are often used to fit such data. Despite the increasing popularity of ZI and hurdle models, there is still a lack of investigation of the fundamental differences between these two types of models. In this article, we reviewed the zero-inflated and hurdle models and highlighted their differences in terms of their data generating processes. We also conducted simulation studies to evaluate the performances of both types of models. The final choice of regression model should be made after a careful assessment of goodness of fit and should be tailored to a particular data in question.