Christina Mair

A Review of Spatial Methods in Epidemiology, 2000–2010

Understanding the impact of place on health is a key element of epidemiologic investigation, and numerous tools are being employed for analysis of spatial health-related data. This review documents the huge growth in spatial epidemiology, summarizes the tools that have been employed, and provides in-depth discussion of several methods. Relevant research articles for 2000-2010 from seven epidemiology journals were included if the study utilized a spatial analysis method in primary analysis (n = 207). Results summarized frequency of spatial methods and substantive focus; graphs explored trends over time. The most common spatial methods were distance calculations, spatial aggregation, clustering, spatial smoothing and interpolation, and spatial regression. Proximity measures were predominant and were applied primarily to air quality and climate science and resource access studies. The review concludes by noting emerging areas that are likely to be important to future spatial analysis in public health.

Alcohol outlet density and intimate partner violence-related emergency department visits.

BACKGROUND Previous research has identified risk factors for intimate partner violence (IPV) severity, injury, and emergency department (ED) visits. These risk factors have been shown at both the individual level (heavy drinking and other substance use on the part of 1 or both partners) and the neighborhood level (residence in an area characterized by poverty and social disadvantage). Alcohol outlet density has been linked with assaultive violence in community settings, but has not been analyzed in relation to IPV-related ED visits. This study examined the effects of outlet densities on IPV-related ED visits throughout California between July 2005 and December 2008. METHODS Half-yearly counts of ED visits related to IPV (E-code 967.3) were computed for each zip code from patient-level public data sets. Alcohol outlet density measures, calculated separately for bars, off-premise outlets, and restaurants, were derived from California Alcohol Beverage Control records. Census-based neighborhood demographic characteristics previously shown to be related to health disparities and IPV (percent black, percent Hispanic, percentage below 150% of poverty line, percent unemployed) were included in models. This study used Bayesian space-time models that allow longitudinal analysis at the zip code level despite frequent boundary redefinitions. These spatial misalignment models control for spatial variation in geographic unit definitions over time and account for spatial autocorrelation using conditional autoregressive (CAR) priors. The model incorporated data from between 1,686 (2005) and 1,693 (2008) zip codes across California for 7 half-year time periods from 2005 through 2008 (n = 11,836). RESULTS Density of bars was positively associated with IPV-related ED visits. Density of off-premise outlets was negatively associated with IPV-related ED visits; this association was weaker and smaller than the bar association. There was no association between density of restaurants and IPV-related ED visits. CONCLUSIONS Further research is needed to understand the mechanisms by which environmental factors, such as alcohol outlet density, affect IPV behaviors resulting in ED visits.

The impacts of marijuana dispensary density and neighborhood ecology on marijuana abuse and dependence

BACKGROUND As an increasing number of states liberalize cannabis use and develop laws and local policies, it is essential to better understand the impacts of neighborhood ecology and marijuana dispensary density on marijuana use, abuse, and dependence. We investigated associations between marijuana abuse/dependence hospitalizations and community demographic and environmental conditions from 2001 to 2012 in California, as well as cross-sectional associations between local and adjacent marijuana dispensary densities and marijuana hospitalizations. METHODS We analyzed panel population data relating hospitalizations coded for marijuana abuse or dependence and assigned to residential ZIP codes in California from 2001 through 2012 (20,219 space-time units) to ZIP code demographic and ecological characteristics. Bayesian space-time misalignment models were used to account for spatial variations in geographic unit definitions over time, while also accounting for spatial autocorrelation using conditional autoregressive priors. We also analyzed cross-sectional associations between marijuana abuse/dependence and the density of dispensaries in local and spatially adjacent ZIP codes in 2012. RESULTS An additional one dispensary per square mile in a ZIP code was cross-sectionally associated with a 6.8% increase in the number of marijuana hospitalizations (95% credible interval 1.033, 1.105) with a marijuana abuse/dependence code. Other local characteristics, such as the median household income and age and racial/ethnic distributions, were associated with marijuana hospitalizations in cross-sectional and panel analyses. CONCLUSIONS Prevention and intervention programs for marijuana abuse and dependence may be particularly essential in areas of concentrated disadvantage. Policy makers may want to consider regulations that limit the density of dispensaries.

Density and Proximity of Tobacco Outlets to Homes and Schools: Relations with Youth Cigarette Smoking

This study investigated the associations of youth cigarette smoking with tobacco outlet densities and proximity of tobacco outlets to youth homes and schools across different buffers in 45 midsized California communities. The sample comprised 832 youths who were surveyed about their smoking behaviors. Inclusion criteria included both home and school addresses within city boundaries. Observations in the 45 cities were conducted to document addresses of tobacco outlets. City- and buffer-level demographics were obtained and negative binomial regression analyses with cluster robust standard errors were conducted. All models were adjusted for youth gender, age, and race. Greater densities of tobacco outlets within both a 0.75 and 1-mile buffer of youth homes were associated with higher smoking frequency. Neither tobacco outlet densities around schools nor distance to the nearest tobacco outlet from home or school were associated with youths past-30-day smoking frequency. Lower population density and percent of African Americans in areas around homes and lower percent of unemployed in areas around schools were associated with greater smoking frequency. Results of this study suggest that restricting outlet density within at least 1-mile surrounding residential areas will help to reduce youth smoking.

Change in neighborhood environments and depressive symptoms in New York City: the multi-ethnic study of atherosclerosis

Physical and social features of neighborhoods, such as esthetic environments and social cohesion, change over time. The extent to which changes in neighborhood conditions are associated with changes in mental health outcomes has not been well-established. Using data from the MultiEthnic Study of Atherosclerosis, this study investigated the degree to which neighborhood social cohesion, stress, violence, safety and/or the esthetic environment changed between 2002 and 2007 in 103 New York City Census tracts and the associations of these changes with changes in depressive symptoms. Neighborhoods became less stressful, more socially cohesive, safer, and less violent. White, wealthy, highly educated individuals tended to live in neighborhoods with greater decreasing violence and stress and increasing social cohesion. Individuals living in neighborhoods with adverse changes were more likely to have increased CES-D scores, although due to limited sample size associations were imprecisely estimated (P>0.05). Changes in specific features of the neighborhood environment may be associated with changes in level of depressive symptoms among residents.

Prevalence of Past-Year Sexual Assault Victimization Among Undergraduate Students: Exploring Differences by and Intersections of Gender Identity, Sexual Identity, and Race/Ethnicity

A critical step in developing sexual assault prevention and treatment is identifying groups at high risk for sexual assault. We explored the independent and interaction effects of sexual identity, gender identity, and race/ethnicity on past-year sexual assault among college students. From 2011 to 2013, 71,421 undergraduate students from 120 US post-secondary education institutions completed cross-sectional surveys. We fit multilevel logistic regression models to examine differences in past-year sexual assault. Compared to cisgender (i.e., non-transgender) men, cisgender women (adjusted odds ratios [AOR] = 2.47; 95% confidence interval [CI] 2.29, 2.68) and transgender people (AOR = 3.93; 95% CI 2.68, 5.76) had higher odds of sexual assault. Among cisgender people, gays/lesbians had higher odds of sexual assault than heterosexuals for men (AOR = 3.50; 95% CI 2.81, 4.35) but not for women (AOR = 1.13; 95% CI 0.87, 1.46). People unsure of their sexual identity had higher odds of sexual assault than heterosexuals, but effects were larger among cisgender men (AOR = 2.92; 95% CI 2.10, 4.08) than cisgender women (AOR = 1.68; 95% CI 1.40, 2.02). Bisexuals had higher odds of sexual assault than heterosexuals with similar magnitude among cisgender men (AOR = 3.19; 95% CI 2.37, 4.27) and women (AOR = 2.31; 95% CI 2.05, 2.60). Among transgender people, Blacks had higher odds of sexual assault than Whites (AOR = 8.26; 95% CI 1.09, 62.82). Predicted probabilities of sexual assault ranged from 2.6 (API cisgender men) to 57.7% (Black transgender people). Epidemiologic research and interventions should consider intersections of gender identity, sexual identity, and race/ethnicity to better tailor sexual assault prevention and treatment for college students.

Who drinks where: youth selection of drinking contexts

BACKGROUND Different drinkers may experience specific risks depending on where they consume alcohol. This longitudinal study examined drinking patterns, and demographic and psychosocial characteristics associated with youth drinking in different contexts. METHODS We used survey data from 665 past-year alcohol-using youths (ages 13 to 16 at Wave 1) in 50 midsized California cities. Measures of drinking behaviors and drinking in 7 contexts were obtained at 3 annual time points. Other characteristics included gender, age, race, parental education, weekly disposable income, general deviance, and past-year cigarette smoking. RESULTS Results of multilevel regression analyses show that more frequent past-year alcohol use was associated with an increased likelihood of drinking at parties and at someone elses home. Greater continued volumes of alcohol (i.e., heavier drinking) was associated with increased likelihood of drinking at parking lots or street corners. Deviance was positively associated with drinking in most contexts, and past-year cigarette smoking was positively associated with drinking at beaches or parks and someone elses home. Age and deviance were positively associated with drinking in a greater number of contexts. The likelihood of youth drinking at parties and someone elses home increased over time, whereas the likelihood of drinking at parking lots/street corners decreased. Also, deviant youths progress to drinking in their own home, beaches or parks, and restaurants/bars/nightclubs more rapidly. CONCLUSIONS The contexts in which youths consume alcohol change over time. These changes vary by individual characteristics. The redistribution of drinking contexts over the early life course may contribute to specific risks associated with different drinking contexts.

Sexual-orientation differences in drinking patterns and use of drinking contexts among college students

BACKGROUND Evidence suggests there are important sexual-orientation differences in alcohol consumption, particularly among women. Little is known about where gay/lesbian and bisexual college students drink or differences in drinking patterns derived from graduated frequency measures between heterosexual, gay/lesbian, and bisexual students. The goal of this analysis was to examine patterns of alcohol consumption-including drinking prevalence, quantity, frequency, and contexts of use-by sexual orientation. METHODS Data on sexual identity, gender, drinking behaviors, and drinking contexts were examined from repeated cross-sectional samples of undergraduate students attending 14 public California universities from 2003-2011 (n=58,903). Multivariable statistical techniques were employed to examine sexual-orientation differences stratified by gender. RESULTS Gay males, lesbians, and bisexual females were significantly more likely to report drinking alcohol in the current semester than their same-gender heterosexual peers (relative risks ranged from 1.07 to 1.10, p-values <0.01). Among current drinkers, bisexual females consumed 7 or more drinks and lesbians consumed 10 or more drinks on significantly more days than heterosexual females. On the other hand, gay male drinkers consumed 8 or more drinks on significantly fewer days than heterosexual male drinkers. Compared to their same-gender heterosexual peers: lesbian/gay and bisexual students drank less frequently at Greek parties (incidence rate ratios [IRRs] ranged from 0.52 to 0.73, p-values <0.01); lesbians (IRR=0.84, p=0.043) and bisexual males (IRR=0.82, p=0.009) drank less frequently at off-campus parties; and gay males drank more frequently outdoors (IRR=1.63, p<0.001) and at bars/restaurants (IRR=1.21, p=0.013). CONCLUSIONS Alcohol prevention programs and future research should consider sexual-orientation differences in drinking patterns and use of drinking contexts.

Reducing Risky Sex Among College Students: Prospects for Context-Specific Interventions

Better understanding the contribution of specific drinking contexts to alcohol use and risky sexual behaviors can help target effective prevention programs to specific locations and types of drinkers. We used a sample of college students to investigate whether more frequent and heavier drinking in specific drinking contexts was associated with unplanned sex, unprotected sex, and number of sexual contacts. Greater frequencies of drinking in almost all contexts (Greek parties, off-campus parties, campus events, dorms, and bars) were associated with greater numbers of sexual partners, unplanned sex and unprotected sex; heavier drinking at bars increased risks related to all outcomes. Risks related to frequencies of use of contexts were similar for men and women, but heavier drinking at bars was associated with more unprotected sex among males only. We discuss these observations in light of their implications for developing context-specific interventions to reduce community viral load in high-risk populations.

Intimate partner violence among California couples: Multilevel analysis of environmental and partner risk factors

This study assessed the extent to which environmental (census block-group alcohol outlet density, neighborhood demographic characteristics) and partner risk factors (e.g., hazardous drinking, psychosocial characteristics) contribute to the likelihood of intimate partner violence (IPV) among 1,753 couples residing in 50 medium-to-large California cities. Multilevel logistic regression models were used to analyze the role of alcohol outlets (off-premise outlets, bars/pubs, and restaurants), neighborhood demographic characteristics, and partner risk factors in relation to male-to-female partner violence (MFPV) and female-to-male partner violence (FMPV) risk. Approximately 12% of couples reported past-year partner violence. Results showed that none of the environmental measures were related to MFPV or FMPV. Male partner’s impulsivity and each partner’s adverse childhood experiences were associated with MFPV risk. Risk factors for FMPV were male partner’s impulsivity and frequency of intoxication and female partner’s adverse childhood experiences. Individual/couple characteristics appear to be the most salient IPV risk factors. The male partner’s heavy drinking may lead to negative partner/spousal interactions that result in FMPV. The male partner’s impulsivity, and each partner’s adverse childhood experiences, may potentiate couple conflict and result in aggression. Interventions that target prevention of family dysfunction during childhood may help reduce interpersonal violence in adulthood.