Sheri A. Lippman

To GEE or not to GEE: comparing population average and mixed models for estimating the associations between neighborhood risk factors and health.

Two modeling approaches are commonly used to estimate the associations between neighborhood characteristics and individual-level health outcomes in multilevel studies (subjects within neighborhoods). Random effects models (or mixed models) use maximum likelihood estimation. Population average models typically use a generalized estimating equation (GEE) approach. These methods are used in place of basic regression approaches because the health of residents in the same neighborhood may be correlated, thus violating independence assumptions made by traditional regression procedures. This violation is particularly relevant to estimates of the variability of estimates. Though the literature appears to favor the mixed-model approach, little theoretical guidance has been offered to justify this choice. In this paper, we review the assumptions behind the estimates and inference provided by these 2 approaches. We propose a perspective that treats regression models for what they are in most circumstances: reasonable approximations of some true underlying relationship. We argue in general that mixed models involve unverifiable assumptions on the data-generating distribution, which lead to potentially misleading estimates and biased inference. We conclude that the estimation-equation approach of population average models provides a more useful approximation of the truth.

Uterine fibroids and gynecologic pain symptoms in a population-based study.

OBJECTIVE To determine the association between dyspareunia, dysmenorrhea, and noncyclic pelvic pain and the presence and characteristics of uterine fibroids. DESIGN Population-based cross-sectional study. SETTING Desio, Italy. PATIENT(S) Six hundred thirty-five non-care-seeking participants of the Seveso Womens Health Study with an intact uterus who underwent transvaginal ultrasound. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Ultrasound-detected presence of uterine fibroids and fibroid characteristics including volume, number, location, and position. Current dyspareunia, dysmenorrhea, and noncyclic pelvic pain was measured by self-report on a visual analog scale. RESULT(S) Uterine fibroids were detected in 96 women (15%). Women with fibroids were more likely to report moderate or severe dyspareunia (adjusted odds ratio [OR] = 2.8, 95% confidence interval [CI] = 0.9-8.3, statistically significant trend) and moderate or severe noncyclic pelvic pain (adjusted OR = 2.6, 95% CI = 0.9-7.6, statistically significant trend) than women without fibroids. Moderate or severe dysmenorrhea was not associated with the presence of fibroids (adjusted OR = 1.1, 95% CI = 0.5-2.6). Number and total volume of fibroids were not related to pain. CONCLUSION(S) This is the first population-based study of gynecologic pain symptoms and fibroids. Dyspareunia and noncyclic pelvic pain, but not dysmenorrhea, increased in severity with the presence of uterine fibroids. Fibroid-associated pain symptomatology in a non-care-seeking population may be different from that of a clinic population.

Gender-Transformative Interventions to Reduce HIV Risks and Violence with Heterosexually-Active Men: A Review of the Global Evidence

Emerging out of increased attention to gender equality within HIV and violence prevention programming has been an intensified focus on masculinities. A new generation of health interventions has attempted to shift norms of masculinity to be more gender equitable and has been termed “gender-transformative.” We carried out a systematic review of gender-transformative HIV and violence prevention programs with heterosexually-active men in order to assess the efficacy of this programming. After reviewing over 2,500 abstracts in a systematic search, a total of 15 articles matched review criteria. The evidence suggests that gender-transformative interventions can increase protective sexual behaviors, prevent partner violence, modify inequitable attitudes, and reduce STI/HIV, though further trials are warranted, particularly in establishing STI/HIV impacts. In the conclusion, we discuss the promises and limitations of gender-transformative work with men and make suggestions for future research focused on HIV and/or violence prevention.

Social-Environmental Factors and Protective Sexual Behavior Among Sex Workers: The Encontros Intervention in Brazil

OBJECTIVES We sought to determine the association of social-environmental factors with condom use and sexually transmitted infections (STIs) among 420 sex workers participating in an STI/HIV prevention study in Corumbá, Brazil, to inform future intervention efforts. METHODS Participants provided urine samples for polymerase chain reaction testing of chlamydia and gonorrhea and responded to multi-item scales addressing perceived social cohesion, participation in networks, and access to and management of resources. We conducted multivariate log-linear and negative binomial regression analyses of these data. RESULTS Increased social cohesion was inversely associated with number of unprotected sex acts in the preceding week among women (adjusted incidence rate ratio [IRR] = 0.80; P < .01), and there was a marginal association among men (adjusted IRR = 0.41; P = .08). Womens increased participation in social networks was associated with a decrease in frequency of unprotected sex acts (adjusted IRR = 0.83; P = .04), as was mens access to and management of social and material resources (IRR = 0.15; P = .01). Social-environmental factors were not associated with STIs. CONCLUSIONS The social context within which populations negotiate sexual behaviors is associated with condom use. Future efforts to prevent STI/HIV should incorporate strategies to modify the social environment.

Using Sexually Transmitted Infection Biomarkers to Validate Reporting of Sexual Behavior within a Randomized, Experimental Evaluation of Interviewing Methods

This paper examines the reporting of sexual and other risk behaviors within a randomized experiment using a computerized versus face-to-face interview mode. Biomarkers for sexually transmitted infection (STI) were used to validate self-reported behavior by interview mode. As part of a parent study evaluating home versus clinic screening and diagnosis for STIs, 818 women aged 18-40 years were recruited in 2004 at or near a primary care clinic in São Paulo, Brazil, and were randomized to a face-to-face interview or audio computer-assisted self-interviewing. Ninety-six percent of participants were tested for chlamydia, gonorrhea, and trichomoniasis. Reporting of STI risk behavior was consistently higher with the computerized mode of interview. Stronger associations between risk behaviors and STI were found with the computerized interview after controlling for sociodemographic factors. These results were obtained by using logistic regression approaches, as well as statistical methods that address potential residual confounding and covariate endogeneity. Furthermore, STI-positive participants were more likely than STI-negative participants to underreport risk behavior in the face-to-face interview. Results strongly suggest that computerized interviewing provides more accurate and reliable behavioral data. The analyses also confirm the benefits of using data on prevalent STIs for externally validating behavioral reporting.

Home-based self-sampling and self-testing for sexually transmitted infections: Acceptable and feasible alternatives to provider-based screening in low-income women in Sao Paulo Brazil.

Objective: The objective of this study was to determine whether home-based screening for sexually transmitted infections (STIs) is acceptable, feasible, and increases the proportion of women screened among low-income women in São Paulo, Brazil. Study Design: Eight hundred eighteen women were randomized to receive a clinic appointment or a kit for home-based STI self-collection and testing. All participants collected 2 vaginal swabs, one for polymerase chain reaction detection of chlamydia, gonorrhea, and trichomoniasis and another for a self-conducted rapid test for trichomoniasis. Results: Slightly more women responded to the initiative within 2 weeks in the home group (80%) than in the clinic group (76%) with younger women showing improved response to home-based screening. Ninety-four percent of home group participants successfully completed self-collection and self-testing on their first attempt. Conclusions: Home-based self-collection and self-testing was acceptable, feasible, and resulted in a slightly higher response rate. Home sampling and testing provide promising alternatives to clinic-based STI screening across diverse contexts.

HIV-related stigma, service utilization, and status disclosure among truck drivers crossing the Southern borders in Brazil

Abstract HIV-related stigma and discrimination (S&D) have been shown to impede prevention, care and treatment. Yet, few quantitative studies have tested the associations between stigma, service utilization and status disclosure, especially in countries with concentrated HIV epidemics. Surveys, administered to a random sample of 1,775 truck drivers crossing Southern borders in Brazil, included items on multiple conceptual domains of S&D, such as fear of casual contact and blame towards people living with HIV/AIDS. Pearsons chi-square tests and logistic regression were used to examine correlations. Less stigma (both individual items and grouped as a scale) was significantly correlated with VCT use (p≤0.001), knowing where to get tested (p≤0.001) and willingness to disclose HIV-positive test results (p=0.013). Findings indicate that stigma is an important barrier to HIV testing and disclosure among truck drivers in Southern Brazil. Learning more about stigma is important given the growing assertions that testing is a ‘critical gateway’ to HIV prevention and treatment. As access to HIV testing and treatment improves, providers increasingly need to understand and address how stigma acts as a barrier to services.

Findings from Encontros: a multilevel STI/HIV intervention to increase condom use, reduce STI, and change the social environment among sex workers in Brazil.

Background: Sexually transmitted infection (STI)/HIV prevention programs, which do not modify social structural contexts that contribute to risk of STI/HIV may fail to bring about improvements in health, particularly among groups who experience discrimination and exclusion from public life. We conducted a multilevel intervention with sex workers, including improved clinical care and community-mobilizing strategies to modify social structural factors that shape sexual behavior, to improve condom use and reduce incident STI. Methods: We followed 420 sex workers participating in the Encontros intervention in Corumbá, Brazil, between 2003 and 2005. We estimated the effect of the intervention on incident chlamydia and gonorrhea infections and condom use using generalized estimating equations and inverse probability weighting by comparing those who actively engaged in the intervention activities (exposed) with those who were less engaged (unexposed). We also determined the association of participation on reported social cohesion and participation in networks. Results: Exposed participants had significantly higher odds of reporting consistent condom use with regular clients (odds ratio [OR]: 1.9, 95% confidence interval:1.1–3.3) and nonsignificantly increased odds with both new clients (OR: 1.6, 0.9–2.8) and nonpaying partners (OR: 1.5, 0.9–1.5). The odds of an incident STI were nonsignificantly reduced for exposed participants compared with unexposed (OR: 0.46, 0.2–1.3). Participation was significantly associated with increased perceived cohesion and participation in networks. Conclusion: This prospective study provides evidence that multilevel interventions with mobilizing strategies to modify aspects of the social environment can improve condom use, reduce STIs, and increase social cohesion and participation in networks among sex workers.

Why increasing availability of ART is not enough: a rapid, community-based study on how HIV-related stigma impacts engagement to care in rural South Africa.

BackgroundStigma is a known barrier to HIV testing and care. Because access to antiretroviral therapy reduces overt illness and mortality, some scholars theorized that HIV-related stigma would decrease as treatment availability increased. However, the association between ART accessibility and stigma has not been as straightforward as originally predicted.MethodsWe conducted a “situational analysis”—a rapid, community-based qualitative assessment to inform a combination HIV prevention program in high prevalence communities. In the context of this community-based research, we conducted semi-structured interviews and focus groups with 684 individuals in four low-resource sub-districts in North West Province, South Africa. In addition to using this data to inform programming, we examined the impact of stigma on the uptake of services.ResultsFindings suggested that anticipated stigma remains a barrier to care. Although participants reported less enacted stigma, or hostility toward people living with HIV, they also felt that HIV remains synonymous with promiscuity and infidelity. Participants described community members taking steps to avoid being identified as HIV-positive, including avoiding healthcare facilities entirely, using traditional healers, or paying for private doctors. Such behaviors led to delays in testing and accessing care, and problems adhering to medications, especially for men and youth with no other health condition that could plausibly account for their utilization of medical services.ConclusionsWe conclude that providing access to ART alone will not end HIV-related stigma. Instead, individuals will remain hesitant to seek care as long as they fear that doing so will lead to prejudice and discrimination. It is critical to combat this trend by increasing cultural acceptance of being seropositive, integrating HIV care into general primary care and normalizing men and youths’ accessing health care.

Conceptualizing Community Mobilization for HIV Prevention: Implications for HIV Prevention Programming in the African Context

Introduction Community mobilizing strategies are essential to health promotion and uptake of HIV prevention. However, there has been little conceptual work conducted to establish the core components of community mobilization, which are needed to guide HIV prevention programming and evaluation. Objectives We aimed to identify the key domains of community mobilization (CM) essential to change health outcomes or behaviors, and to determine whether these hypothesized CM domains were relevant to a rural South African setting. Method We studied social movements and community capacity, empowerment and development literatures, assessing common elements needed to operationalize HIV programs at a community level. After synthesizing these elements into six essential CM domains, we explored the salience of these CM domains qualitatively, through analysis of 10 key informant in-depth-interviews and seven focus groups in three villages in Bushbuckridge. Results CM domains include: 1) shared concerns, 2) critical consciousness, 3) organizational structures/networks, 4) leadership (individual and/or institutional), 5) collective activities/actions, and 6) social cohesion. Qualitative data indicated that the proposed domains tapped into theoretically consistent constructs comprising aspects of CM processes. Some domains, extracted from largely Western theory, required little adaptation for the South African context; others translated less effortlessly. For example, critical consciousness to collectively question and resolve community challenges functioned as expected. However, organizations/networks, while essential, operated differently than originally hypothesized - not through formal organizations, but through diffuse family networks. Conclusions To date, few community mobilizing efforts in HIV prevention have clearly defined the meaning and domains of CM prior to intervention design. We distilled six CM domains from the literature; all were pertinent to mobilization in rural South Africa. While some adaptation of specific domains is required, they provide an extremely valuable organizational tool to guide CM programming and evaluation of critically needed mobilizing initiatives in Southern Africa.