Faculty Bibliography

Recent interest by physicists in social networks and disease transmission factors has prompted debate over the topology of degree distributions in sexual networks. Social network researchers have been critical of "scale-free" Barabasi-Albert approaches, and largely rejected the preferential attachment, "rich-get-richer" assumptions that underlie that model. Instead, research on sexual networks has pointed to the importance of homophily and local sexual norms in dictating degree distributions, and thus disease transmission thresholds. Injecting Drug User (IDU) network topologies may differ from the emerging models of sexual networks, however. Degree distribution analysis of a Brooklyn, NY, IDU network indicates a different topology than the spanning tree configurations discussed for sexual networks, instead featuring comparatively short cycles and high concurrency. Our findings suggest that IDU networks do in some ways conform to a "scale-free" topology, and thus may represent "reservoirs" of potential infection despite seemingly low transmission thresholds.

Patterns of risk in injecting drug user (IDU) networks have been a key focus of network approaches to HIV transmission histories. New network modeling techniques allow for a reexamination of these patterns with greater statistical accuracy and the comparative weighting of model elements. This paper describes the results of a reexamination of network data from the SFHR and P90 data sets using Exponential Random Graph Modeling. The results show that "transitive closure" is an important feature of IDU network topologies, and provides relative importance measures for race/ethnicity, age, gender, and number of risk partners in predicting risk relationships.

BACKGROUND:During 2011, a dramatic increase (1600%) of reported HIV-1 infections among injecting drug users (IDUs) was noted in Athens, Greece. We herein assess the potential causal pathways associated with this outbreak. METHODS:Our study employed high resolution HIV-1 phylogenetic and phylogeographic analyses. We examined also longitudinal data of ecological variables such as the annual growth of gross domestic product (GDP) of Greece in association with HIV-1 and HCV sentinel prevalence in IDUs, unemployment and homelessness rates and HIV transmission networks in Athens IDUs before and during economic recession (2008-2012). RESULTS:IDU isolates sampled in 2011 and 2012 suggested transmission networks in 94.6% and 92.7% of the cases in striking contrast with the sporadic networking (5%) during 1998-2009. The geographic origin of most HIV-1 isolates was consistent with the recently documented migratory waves in Greece. The decline in GDP was inversely correlated with annual prevalence rates of HIV and HCV and with unemployment and homelessness rates in IDUs (all p<0.001). The slope of anti-HCV prevalence in the sentinel populations of IDUs and in "new" drug injectors was found 120 and 1.9-fold (p = 0.007, p = 0.08 respectively) higher in 2008-2012 (economic recession) compared with 2002-2006. The median (25th, 75th) size of transmission networks were 34 (12, 58) and 2 (2, 2) (p = 0.057) in 2008-2012 and 1998-2007, respectively. The coverage of harm reduction services was low throughout the study period. CONCLUSIONS:Scaling-up harm reduction services and addressing social and structural factors related to the current economic crisis should be urgently considered in environments where HIV-1 outbreaks may occur.

BACKGROUND:In HIV infection, initiation of treatment is associated with improved clinical outcom and reduced rate of sexual transmission. However, difficulty in detecting infection in early stages impairs those benefits. We determined the minimum testing rate that maximizes benefits derived from early diagnosis. METHODS:We developed a mathematical model of HIV infection, diagnosis and treatment that allows studying both diagnosed and undiagnosed populations, as well as determining the impact of modifying time to diagnosis and testing rates. The model's external consistency was assessed by estimating time to AIDS and death in absence of treatment as well as by estimating age-dependent mortality rates during treatment, and comparing them with data previously reported from CASCADE and DHCS cohorts. RESULTS:In our model, life expectancy of patients diagnosed before 8 years post infection is the same as HIV-negative population. After this time point, age at death is significantly dependent on diagnosis delay but initiation of treatment increases life expectancy to similar levels as HIV-negative population. Early mortality during HAART is dependent on treatment CD4 threshold until 6 years post infection and becomes dependent on diagnosis delay after 6 years post infection. By modifying testing rates, we estimate that an annual testing rate of 20% leads to diagnosis of 90% of infected individuals within the first 8.2 years of infection and that current testing rate in middle-high income settings stands close to 10%. In addition, many differences between low-income and middle-high incomes can be predicted by solely modifying the diagnosis delay. CONCLUSIONS:To increase testing rate of undiagnosed HIV population by two-fold in middle-high income settings will minimize early mortality during initiation of treatment and global mortality rate as well as maximize life expectancy. Our results highlight the impact of achieving early diagnosis and the importance of strongly work on improving HIV testing rates.

BACKGROUND:Based on a stress-coping framework, the present study investigates the relationship between discrimination and substance use, and the moderating effects of gender. METHODS:This cross-sectional study analyzes data from Latina/o young adults aged 18-25 (N = 401) from Brooklyn, New York. Multinomial logistic regression was used to test the association between discrimination and substance use. RESULTS:Discrimination was significantly associated with increased odds of substance use adjusting for covariates (e.g. age, education). Gender was a moderator. Discrimination was associated with increased risk of alcohol/cannabis and hard drug use among young Latina women. However, discrimination was associated with decreased risk of alcohol/cannabis use and increased risk of hard drug use among young Latino men. CONCLUSION/CONCLUSIONS:These findings suggest that discrimination is generally associated with risk for substance use, but further that the outcomes vary by gender. Future research should explore gender-specific dimensions of discrimination and their associations with other outcomes.

As they age, gay and bisexual men are embedded in multiple environments and communities. This article reanalyzes data collected as part of a larger qualitative study of crystal methamphetamine use in New York City. Focusing on the migration narratives of 30 racially/ethnically diverse men, age 40 years old and older, recruited from multiple venues several key areas emerged: ostracization, lack of affirmation as well as movement activities. Interactively they transformed social practices and increased spaces to explore sexuality, build community engagements and exchange resources. This study suggests that assessment of gay men (and other marginalized groups) may be enhanced through application of migration narratives.

BACKGROUND:Among the largest US metropolitan areas, trends in mortality rates for injection drug users (IDUs) with AIDS vary substantially. Ecosocial, risk environment and dialectical theories suggest many metropolitan areas characteristics that might drive this variation. We assess metropolitan area characteristics associated with decline in mortality rates among IDUs living with AIDS (per 10,000 adult MSA residents) after highly active antiretroviral therapy (HAART) was developed. METHODS:This is an ecological cohort study of 86 large US metropolitan areas from 1993-2006. The proportional rate of decline in mortality among IDUs diagnosed with AIDS (as a proportion of adult residents) from 1993-1995 to 2004-2006 was the outcome of interest. This rate of decline was modeled as a function of MSA-level variables suggested by ecosocial, risk environment and dialectical theories. In multiple regression analyses, we used 1993-1995 mortality rates to (partially) control for pre-HAART epidemic history and study how other independent variables affected the outcomes. RESULTS:In multivariable models, pre-HAART to HAART era increases in 'hard drug' arrest rates and higher pre-HAART income inequality were associated with lower relative declines in mortality rates. Pre-HAART per capita health expenditure and drug abuse treatment rates, and pre- to HAART-era increases in HIV counseling and testing rates, were weakly associated with greater decline in AIDS mortality. CONCLUSIONS:Mortality among IDUs living with AIDS might be decreased by reducing metropolitan income inequality, increasing public health expenditures, and perhaps increasing drug abuse treatment and HIV testing services. Given prior evidence that drug-related arrest rates are associated with higher HIV prevalence rates among IDUs and do not seem to decrease IDU population prevalence, changes in laws and policing practices to reduce such arrests while still protecting public order should be considered.

Cigarette smoking is influenced both by genetic and environmental factors. Until this year, all large-scale gene identification studies on smoking were conducted in populations of European ancestry. Consequently, the genetic architecture of smoking is not well described in other populations. Further, despite a rich epidemiologic literature focused on the social determinants of smoking, few studies have examined the moderation of genetic influences (for example, gene-environment interactions) on smoking in African Americans. In the Detroit Neighborhood Health Study (DNHS), a sample of randomly selected majority African American residents of Detroit, we constructed a genetic risk score (GRS), in which we combined top (P-value <5 × 10(-7)) genetic variants from a recent meta-analysis conducted in a large sample of African Americans. Using regression (effective n=399), we first tested for association between the GRS and cigarettes per day, attempting to replicate the findings from the meta-analysis. Second, we examined interactions with three social contexts that may moderate the genetic association with smoking: traumatic events, neighborhood social cohesion and neighborhood physical disorder. Among individuals who had ever smoked cigarettes, the GRS significantly predicted the number of cigarettes smoked per day and accounted for ~3% of the overall variance in the trait. Significant interactions were observed between the GRS and number of traumatic events experienced, as well as between the GRS and average neighborhood social cohesion; the association between genetic risk and smoking was greater among individuals who had experienced an increased number of traumatic events in their lifetimes, and diminished among individuals who lived in a neighborhood characterized by greater social cohesion. This study provides support for the utility of the GRS as an alternative approach to replication of common polygenic variation, and in gene-environment interaction, for smoking behaviors. In addition, this study indicates that environmental determinants have the potential to both exacerbate (traumatic events) and diminish (neighborhood social cohesion) genetic influences on smoking behaviors.

PURPOSE/OBJECTIVE:Ongoing traumatic events and stressors, rather than acute sources of trauma, may shape long-term post-disaster mental health. The purpose of this study was to compare the influence of acute hurricane-related exposures and ongoing post-hurricane exposures on the short- and long-term course of posttraumatic stress symptoms (PTSS) and functional impairment (FI). METHODS:A random sample of adults (n = 658) in Galveston and Chambers Counties, Texas, was selected 2-6 months after Hurricane Ike and interviewed 3 times over 18 months. Hurricane-related exposures included traumatic events such as death of a family member due to the hurricane and stressors such as loss/damage to personal property due to the hurricane. Post-hurricane exposures included traumatic events such as sexual assault and stressors such as divorce or serious financial problems. RESULTS:Experiencing an acute hurricane-related traumatic event or stressor was associated with initial post-hurricane PTSS [RR = 1.92 (95% CI = 1.13-3.26) and RR = 1.62 (1.36-1.94), respectively] and FI [RR = 1.76; (1.05-2.97) and RR = 1.74 (1.46-2.08)], respectively, and acute hurricane-related stressors were associated with a higher rate of increase in FI over time [RR = 1.09; (1.01-1.19)]. In contrast, ongoing post-hurricane daily stressors were not associated within initial PTSS and FI, but were associated with PTSS and FI at the second and third interviews. CONCLUSIONS:While immediate postdisaster interventions may influence short-term mental health, investment in the prevention of ongoing stressors may be instrumental to manage long-term mental health status.