Using geographically weighted regression (GWR) to explore spatial varying relationships of immature mosquitoes and human densities with the incidence of dengue

The only way for dengue to spread in the human population is through the human-mosquito-human cycle. Most research in this field discusses the dengue-mosquito or dengue-human relationships over a particular study area, but few have explored the local spatial variations of dengue-mosquito and dengue-human relationships within a study area. This study examined whether spatial heterogeneity exists in these relationships. We used Ordinary Least Squares (OLS) and Geographically Weighted Regression (GWR) models to analyze spatial relationships and identify the geographical heterogeneities by using the information of entomology and dengue cases in the cities of Kaohsiung and Fengshan in 2002. Our findings indicate that dengue-mosquito and dengue-human relationships were significantly spatially non-stationary. This means that in some areas higher dengue incidences were associated with higher vector/host densities, but in some areas higher incidences were related to lower vector/host densities. We demonstrated that a GWR model can be used to geographically differentiate the relationships of dengue incidence with immature mosquito and human densities. This study provides more insights into spatial targeting of intervention and control programs against dengue outbreaks within the study areas.     

Exploring racial disparities in CHD mortality between blacks and whites across the United States: A geographically weighted regression approach

Coronary heart disease (CHD) mortality is one of the major contributors to racial disparities in health in the United States (US). We examined spatial heterogeneity in black-white differences in CHD mortality across the US and assessed the contributions of poverty and segregation. We used county-level, age-adjusted CHD mortality rates for blacks and whites in the continental US between 1996 and 2006. Geographically weighted regression was employed to assess spatial heterogeneity. There was significant spatial heterogeneity in black-white differences in CHD mortality (median black-white difference 17.7 per 100,000, 25th-75th percentile (IQR): 4.0, 34.0, P value for spatial non-stationarity <0.0001) before controlling for poverty and segregation. This heterogeneity was no longer present after accounting for county differences in race-specific poverty and segregation and interactions of these variables with race (median black-white difference -13.5 per 100,000, IQR: -41.3, 15.7,P value for spatial non-stationarity=0.4346). The results demonstrate the importance of spatial heterogeneity in understanding and eliminating racial disparities in CHD mortality. Additional research to identify the individual and contextual factors that explain the local variations in racial disparities is warranted.     

Understanding the non-stationary associations between distrust of the health care system, health conditions, and self-rated health in the elderly: a geographically weighted regression approach

The goals of this study are to explore whether health condition is an antecedent extraneous factor for the relationship between health care system distrust and self-rated health among the elderly, and to investigate if the associations among these variables are place-specific. We used logistic geographically weighted regression to analyze data on an elderly sample residents in the Philadelphia metropolitan area. We found that the health conditions of the elderly account for the association between high distrust and poor/fair self-rated health and that the distrust/self-rated health relationship varied spatially. This finding suggests that a place-centered perspective can inform distrust/self-rated health research.     

Social capital and rates of gonorrhea and syphilis in the United States: spatial regression analyses of state-level associations

We conducted spatial regression analysis to account for spatial clustering of sexually transmitted diseases (STDs) and to examine the state-level association between social capital (using Putnam's public use data set) and rates of gonorrhea and syphilis. We conducted the analysis for the 48 contiguous states of the United States for 1990, 1995, and 2000 and controlled for the effects of regional variation in STD rates, and for state variation in poverty, income inequality, racial composition, and percentage aged 15-34 years. We compared the results of the spatial regression analysis with those of ordinary least squares (OLS) regression. Controlling for all population-level variables, the percentage of variation explained by the OLS regression and by the spatial regression were similar (mid-90s for gonorrhea and low-70s for syphilis), the standardized parameter estimates were similar, and the spatial lag parameter was not statistically significant. Social capital was not associated with STD rates when state variation in racial composition was included in the regression analysis. In this analysis, states with a higher proportion of residents who were African-American had higher STD rates. When we did not control for racial composition, regression analysis showed that states with higher social capital had lower STD rates. We conjecture that sexual networks and sexual mixing drive the association between social capital and STD rates and highlight important measurement and research questions that need elucidation to understand fully the relationship between social capital and STDs.     

Introduction of a HIV vaccine in developing countries: social and cultural dimensions

Using insights from studies on social and cultural aspects of immunization in Africa and Asia the paper discusses the introduction of a HIV vaccine from three perspectives. Firstly, it shows how at the side of public health programs local differences will impact on the introduction of a new vaccine. Secondly, it elaborates how at the side of the users of vaccinations acceptance, non-acceptance and demand of and for a new vaccine are related to local vaccination cultures, images of the HIV/AIDS epidemic, and perceptions of vaccine potency and efficacy. Thirdly, it points out socio-cultural aspects of the introductory process. Tailoring health education and social marketing to local conditions and local interpretations of globally provided information will be decisive for a successful introduction. Strong public health programs with highly motivated and appropriately supported staff are another necessary condition.     

Geography of suicide in Taiwan: spatial patterning and socioeconomic correlates

In industrialised Western nations suicide rates tend to be high in inner city areas and socially fragmented neighbourhoods. Few studies have investigated spatial variations in suicide in non-Western settings. We estimated smoothed standardised mortality ratios (1999-2007) for suicide for each of the 358 Taiwanese districts (median population aged 15+: 27,000) and investigated their associations with area characteristics using Bayesian hierarchical models. The geographic distribution of suicide was similar in men and women; young people showed the greatest spatial variation in rates. Rates were highest in East Taiwan, a mostly mountainous rural area. There was no evidence of above average rates in large cities. Spatial patterns of method-specific suicide rates varied markedly, with solids/liquids poisonings showing the greatest geographic variation and hangings the least. Factors most strongly associated with area suicide rates were median household income, population density and lone-parent households. Spatial patterning of suicide in Taiwan differed from that observed in Western nations. Suicide prevention strategies should take into account unique local patterns.     

The geography of self-injury: spatial patterns in attempted and completed suicide

This study uses hospital discharge data, death certificates and medical examiner data for New Jersey for 1999-2001 to investigate whether fatal and non-fatal self-injury exhibit similar geographic patterns. Findings show that the demographic characteristics of individuals committing fatal and non-fatal self-injury are quite different. Furthermore, attempted and completed suicides have a somewhat different geographical pattern. Municipality-level determinants of suicide and non-fatal self-injury were estimated in two separate models. While measures of isolation such as low population density and high proportions of households with only one member were predictive of completed suicides, non-fatal self-injury was related to unemployment and median age. Both types of self-injury were more common in municipalities which lost population between 1990 and 2000, and where divorce rates were high. Population-based suicide prevention efforts should be aided by the knowledge that although there are some similarities in the spatial pattern of completed and attempted suicides, there are some important differences in significant determinants.     

Using geographically weighted regression for social inequality analysis: association between mentally unhealthy days (MUDs) and socioeconomic status (SES) in U.S. counties

This research explores geographic variability of factors on social inequality related to mental health in the United States using county-level data in 2014. First, we account for complex design factors in Behavioural Risk Factor Surveillance System (BRFSS) data such as clustering, stratification, and sample weight using Complex Samples General Linear Model (CSGLM). Then, three variables are used in the model as indicators of social inequality, low socioeconomic status (SES): unemployment, education status, and social association status. A geographically weighted regression analysis is applied to examine the spatial variations in the associations of mentally unhealthy days (MUDs) with the indicators of SES in the United States. The results demonstrate that unemployment and education level show global positive and negative influences respectively on MUDs. Social association status ranged from positive to negative across the United States, implying some geographic clustering. These findings suggest that social and health policies should be adjusted to address the different effects of indicators of social inequality on mental health across different social characteristics of communities to more effectively manage mental health problems.     

Effectiveness of brief intervention and contact for suicide attempters: a randomized controlled trial in five countries

OBJECTIVE: To determine whether brief intervention and contact is effective in reducing subsequent suicide mortality among suicide attempters in low and middle-income countries. METHODS: Suicide attempters (n = 1867) identified by medical staff in the emergency units of eight collaborating hospitals in five culturally different sites (Campinas, Brazil; Chennai, India; Colombo, Sri Lanka; Karaj, Islamic Republic of Iran; and Yuncheng, China) participated, from January 2002 to October 2005, in a randomized controlled trial to receive either treatment as usual, or treatment as usual plus brief intervention and contact (BIC), which included patient education and follow-up. Overall, 91% completed the study. The primary study outcome measurement was death from suicide at 18-month follow-up. FINDINGS: Significantly fewer deaths from suicide occurred in the BIC than in the treatment-as-usual group (0.2% versus 2.2%, respectively; chi2 = 13.83, P < 0.001). CONCLUSION: This low-cost brief intervention may be an important part of suicide prevention programmes for underresourced low- and middle-income countries.     

Assessing HIV resistance in developing countries: Brazil as a case study.

Increased transmission of resistant HIV has been raised as a potential consequence of expanded access to antiretroviral therapy. We review how limitations in resources and health care infrastructure may impact the transmission of resistant HIV, and we examine data from Brazil as a case study. We introduce a biological and clinical framework to identify the major determinants of transmitted resistance and to discuss how these determinants may be affected by a lack of infrastructure. We then use our framework to examine HIV resistance data from Brazil. This country was chosen as a case study due to its extensive experience delivering antiretroviral drugs and because of the availability of data on the prevalence of resistant HIV there. The data from Brazil show that antiretroviral therapy can be delivered in a resource-limited setting without resulting in widespread transmission of resistant virus. While the Brazilian experience does not necessarily generalize to countries with less health care infrastructure, neither theory nor data support a foregone conclusion that resistance will necessarily dominate HIV epidemics in the developing world to a greater extent than it does in the developed world.     

Neighborhood social capital and crime victimization: Comparison of spatial regression analysis and hierarchical regression analysis

Crime is an important determinant of public health outcomes, including quality of life, mental well-being, and health behavior. A body of research has documented the association between community social capital and crime victimization. The association between social capital and crime victimization has been examined at multiple levels of spatial aggregation, ranging from entire countries, to states, metropolitan areas, counties, and neighborhoods. In multilevel analysis, the spatial boundaries at level 2 are most often drawn from administrative boundaries (e.g. Census tracts in the U.S.). One problem with adopting administrative definitions of neighborhoods is that it ignores spatial spillover. We conducted a study of social capital and crime victimization in one ward of Tokyo city, using a Spatial Durbin Model with an inverse-distance weighting matrix that assigned each respondent a unique level of "exposure" to social capital based on all other residents' perceptions. The study is based on a postal questionnaire sent to 20-69 years old residents of Arakawa Ward, Tokyo. The response rate was 43.7%. We examined the contextual influence of generalized trust, perceptions of reciprocity, two types of social network variables, as well as two principal components of social capital (constructed from the above four variables). Our outcome measure was self-reported crime victimization in the last five years. In the Spatial Durbin Model, we found that neighborhood generalized trust, reciprocity, supportive networks and two principal components of social capital were each inversely associated with crime victimization. By contrast, a multilevel regression performed with the same data (using administrative neighborhood boundaries) found generally null associations between neighborhood social capital and crime. Spatial regression methods may be more appropriate for investigating the contextual influence of social capital in homogeneous cultural settings such as Japan.     

Behavioural interventions for HIV positive prevention in developing countries: a systematic review and meta-analysis

Objective

To assess the evidence for a differential effect of positive prevention interventions among individuals infected and not infected with human immunodeficiency virus (HIV) in developing countries, and to assess the effectiveness of interventions targeted specifically at people living with HIV.

Methods

We conducted a systematic review and meta-analysis of papers on positive prevention behavioural interventions in developing countries published between January 1990 and December 2006. Standardized methods of searching and data abstraction were used. Pooled effect sizes were calculated using random effects models.

Findings

Nineteen studies met the inclusion criteria. In meta-analysis, behavioural interventions had a stronger impact on condom use among HIV-positive (HIV+) individuals (odds ratio, OR: 3.61; 95% confidence interval, CI: 2.61–4.99) than among HIV-negative individuals (OR: 1.32; 95% CI: 0.77–2.26). Interventions specifically targeting HIV+ individuals also showed a positive effect on condom use (OR: 7.84; 95% CI: 2.82–21.79), which was particularly strong among HIV-serodiscordant couples (OR: 67.38; 95% CI: 36.17–125.52). Interventions included in this review were limited both in scope (most were HIV counselling and testing interventions) and in target populations (most were conducted among heterosexual adults or HIV-serodiscordant couples).

Conclusion

Current evidence suggests that interventions targeting people living with HIV in developing countries increase condom use, especially among HIV-serodiscordant couples. Comprehensive positive prevention interventions targeting diverse populations and covering a range of intervention modalities are needed to keep HIV+ individuals physically and mentally healthy, prevent transmission of HIV infection and increase the agency and involvement of people living with HIV.     

The role of firearm and alcohol availability in firearm suicide: A population-based weighted case-control study

Firearm availability has been linked to firearm self-harm, but the joint relationship with alcohol availability, while supported by theory, has not been examined. This study sought to quantify the separate and joint relations of community firearm and alcohol availability with individual-level risk of (fatal and nonfatal) firearm self-harm. We conducted a case-control study of California residents, 2005–2015, using statewide mortality, hospital, firearm transfer, and alcohol license data. We estimated monthly marginal risk differences per 100,000 in the overall population and in white men aged 50+ under various hypothetical changes to firearm and alcohol availability and assessed additive interactions using case-control-weighted g-computation. In the overall population, non-pawn shop firearm dealer density was associated with firearm self-harm (RD: 0.02, 95% CI: 0.003, 0.04) but pawn shop firearm dealer and alcohol outlet densities were not. Secondary analyses revealed a relationship between firearm sales density and firearm self-harm (RD: 0.07, 95% CI: 0.04, 0.10). There were no additive interactions between measures of firearm and alcohol availability. Among older white men, generally the same exposures were related to self-harm as in the overall population, but point estimates were substantially larger. Findings suggest community-level approaches to reducing firearm sales may help mitigate suicide risk.     

Simultaneous and iterative weighted regression analysis of toxicity tests using a microplate reader.

A system is described for determination of LC50 or IC50 by an iterative process based on data obtained from a plate reader using a marine unicellular alga as a target species. The esterase activity of Tetraselmis suesica on fluorescein diacetate as a substrate was measured using a fluorescence titerplate. Simultaneous analysis of results was performed using an iterative process adopting the sigmoid function Y = y/1 (dose of toxicant/IC50)slope for dose-response relationships. IC50 (+/- SEM) was estimated (P less than 0.05). An application with phosalone as a toxicant is presented.     

Cost-effectiveness of HIV screening in high-income countries: A systematic review

IntroductionOver 2 million people in high-income countries live with HIV. Early diagnosis and treatment present benefits for infected subjects and reduce secondary transmissions. Cost-effectiveness analyses are important to effectively inform policy makers and consequently implement the most cost-effective programmes. Therefore, we conducted a systematic review regarding the cost-effectiveness of HIV screening in high-income countries.MethodsWe followed PRISMA statements and included all papers evaluating the cost-effectiveness of HIV screening in the general population or in specific subgroups.ResultsThirteen studies considered routine HIV testing in the general population. The most cost-effective option appeared to be associating one-time testing of the general population with annual screening of high-risk groups, such as injecting-drug users. Thirteen studies assessed the cost-effectiveness of HIV screening in specific settings, outlining the attractiveness of similar programmes in emergency departments, primary care, sexually transmitted disease clinics and substance abuse treatment programmes.DiscussionEvidence regarding the health benefits and cost-effectiveness of HIV screening is growing, even in low-prevalence countries. One-time screenings offered to the adult population appear to be a valuable choice, associated with repeated testing in high-risk populations. The evidence regarding the benefits of using a rapid test, even in terms of cost-effectiveness, is growing. Finally, HIV screening seems useful in specific settings, such as emergency departments and STD clinics.