Population Health: Behavioral and Social Science Insights

By David R. Holtgrave, Cathy Maulsby, Chris Adkins, and Laura W. Fuentes

Abstract

In July 2010, President Barack Obama released the first ever comprehensive HIV/AIDS strategy for the United States. The U.S. National HIV/AIDS Strategy (NHAS) contained goals to be achieved by 2015 in four major areas: (1) reduction of HIV incidence; (2) improved linkage to HIV care, treatment, and housing services; (3) reduction of health disparities; and enhanced service coordination. Here, we describe the contributions that the behavioral and social sciences have made in the past to these four broad domains, and we describe how the behavioral and social sciences can help monitor and achieve the 2015 NHAS goals, as well as help to plan for the next iteration of the NHAS for 2016 and beyond. It is clear from this review and analysis that behavioral and social science contributions are essential to achieving an AIDS-free generation in the near term.

Introduction

The human immunodeficiency virus (HIV) causes acquired immunodeficiency syndrome (AIDS) and has cumulatively infected over 75 million persons globally and 1.8 million persons in the United States since the late 1970s.^1-3 These infections have resulted in more than 39 million deaths worldwide and over 650,000 deaths in the United States alone.^2,3 HIV has been a part of the public discourse about health for over 30 years, and discussions about human sexual behavior, substance use, and social determinants of health have been forever altered by this epidemic.^4-6

Despite the widespread impact of the epidemic, and the U.S. investment of hundreds of billions of dollars in addressing HIV/AIDS,^2,7 it was not until 2010 that the United States had a truly comprehensive National HIV/AIDS Strategy (NHAS).⁸ Released in July 2010 by President Barack Obama, the NHAS sought to reduce the spread of HIV, help persons living with HIV obtain high quality medical care, decrease HIV/AIDS health disparities, and improve coordination of HIV-related activities in the public and private sectors.

In this chapter, we briefly describe the goals of the NHAS (which runs from 2010 through 2015) and then highlight the roles that the behavioral and social sciences can play in making the NHAS a success. To do so, we highlight key advances in behavioral epidemiology, prevention intervention development, social determinants and structural intervention development, and behavioral factors in care and treatment. Next, we discuss how emerging biomedical advances have changed the landscape and provided new opportunities for behavioral and social science contributions to HIV prevention and care in synergy with biomedical breakthroughs. We then discuss key economic analyses related to HIV prevention and care and describe how such analyses can help inform the setting of the next generation of national strategy goals for 2016 and beyond. We conclude by highlighting some key implications for practice and future research.

Overview of the National HIV/AIDS Strategy

The NHAS has four major sections with goals stated for the time period 2010 through 2015;⁸ all NHAS goals are quoted in Table 1. The first section calls for a reduction in new HIV infections, a decrease in the annual HIV transmission rate (defined as HIV incidence in a given year divided by HIV prevalence in that year, then multiplied by 100 for ease of exposition), and an increase in the level of awareness of seropositivity among persons living with HIV.

Table 1. National HIV/AIDS Strategy Goals: 2010 through 2015

Note: All headings and goals in this table are presented as they are stated in the Federal National HIV/AIDS Strategy issued in July 2010.
Key: AIDS = acquired immunodeficiency syndrome; HIV = human immunodeficiency virus; HUD = Housing and Urban Development

The second section of Table 1 highlights the need for increased linkage to and retention in care and treatment among persons living with HIV (PLWH) and improvements in the provision of stable housing for homeless or unstably-housed PLWH. Figure 1 displays the remarkable drop-off in the number of persons living with HIV who are diagnosed, linked to care, retained in care, prescribed antiretroviral therapy, and achieve viral suppression.^9,10 Clearly, improvements in the provision of HIV care in the United States are urgently needed. The goals of this section largely are stated in terms of the population of clients receiving HIV care under the Ryan White Care Act programs (the Federal provider of last resort in the United States);^11,12 this is subtly but importantly different than stating goals for the entire population of persons living with HIV.

Figure 1: HIV Care Continuum for the United States

Source: Centers for Disease Control and Prevention; 2013. Available at http://www.cdc.gov/nchhstp/newsroom/docs/HIVFactSheets/TodaysEpidemic-508.pdf

The third section of the NHAS (Table 1) discusses key health disparities in which communities are most heavily impacted by HIV. According to the Centers for Disease Control and Prevention (CDC), the 10 communities most disproportionately impacted by new HIV infections are white, black, and Hispanic men who have sex with men (MSM), black heterosexual women and men, white and Hispanic heterosexual women, black males and black females who inject drugs, and Hispanic heterosexual men).¹⁰ Further, this section of the NHAS discusses in detail root causes of the HIV epidemic such as HIV-related stigma, discrimination, homophobia, poverty, and social inequality. While these social drivers of the epidemic are discussed in the NHAS, the goals of this section are all framed in terms of increases in viral suppression in three heavily and disproportionately impacted communities (Table 1).

The fourth section of the NHAS notes the importance of the coordination of all HIV/AIDS related services. These goals are phrased as a pair of process goals rather than disease-specific outcome or impact goals (Table 1).

Throughout the NHAS, it is emphasized that no one of these four sections can stand alone, but rather they must operate in a synergistic way to truly impact the course of the epidemic in the United States. This is especially important because the findings of the highly influential National Institutes of Health (NIH)-sponsored trial "HPTN 052" demonstrated that HIV treatment can also serve critical prevention purposes by suppressing viral load to a point that HIV transmission to HIV seronegative partners is indeed a very rare occurrence.^13,14 Hence, the lines between prevention and treatment have been heavily blurred in recent years, and one cannot truly discuss one section of the NHAS without the other.

Behavioral and Social Science Achievements Relevant to Four Sections of the NHAS

Modes of Transmission and Behavioral Epidemiology

As students of the behavioral and social sciences are certainly aware, these disciplines have seen research findings unfold over the past decades of direct relevance to the four sections of the NHAS. Here we describe a selected set of highlights of these findings (noting again that all parts of the NHAS are truly synergistic); in the following sections of this chapter, we describe future challenges for the behavioral and social sciences to best achieve the goals of the NHAS through 2015 and help establish goals for 2016 and beyond.

HIV is transmitted when there is unprotected risk behavior (generally sexual or drug injection risk behavior) in a serodiscordant partnership in which the partner living with HIV has unsuppressed virus.¹⁵ Of course, this "partnership" maybe as brief as one sexual or drug-sharing encounter, or it may involve many encounters over a long period of time. This simple sentence has important implications; it means that if there are no transmission-relevant risk behaviors or if there is well- suppressed virus (or both), then transmission is indeed a very rare event (with the probability of transmission approaching zero). This implication provides two critical pathways for disrupting HIV transmission. First, transmission-relevant risk behaviors can be modified or eliminated, and second, viral levels in persons living with HIV can be suppressed.^15-17 The behavioral and social sciences have made important contributions to both main prevention pathways; we review each here in turn.

Regarding the identification and modification of HIV transmission-relevant risk behaviors, there is a rich history of success in the behavioral and social sciences. Behavioral and social scientists contributed in fundamental ways to the earliest cohort studies that helped elucidate the patterns of HIV transmission, the behaviors that transmitted the virus, and the consequences of transmission.^18-20

Prevention Intervention Development

Almost as soon as the modes of transmission were identified and the disproportionate impact on some communities was known, behavioral and social scientists began to develop interventions that sought to provide information about HIV, shape attitudes toward protecting one's self and one's partners from becoming infected, and modify behaviors (such as increasing condom use and elevating use of sterile injection equipment among persons who inject drugs). The earliest of these interventions were developed in the late 1980s and published in the early 1990s.^21,22 In the 1990s, the National Institute of Mental Health (NIMH) made a substantial investment in the development of individual-level and small-group-level interventions for a variety of heavily impacted communities, such as gay and bisexual men, persons who inject drugs, and heterosexual women (with communities of color being very disproportionately affected). Because intervention trials with HIV incidence as an outcome measure would be very expensive, NIH chose during this era to fund projects with psychometrically rigorous behavior change measures and non-HIV sexually transmitted infections (STIs) as outcome metrics;²³ this allowed more numerous, smaller scale studies to be done on a variety of intervention types for several communities at risk, rather than a very few large trials with HIV incidence as the outcome. This line of research led to the development of dozens of interventions capable of changing HIV-relevant risk behavior and a number with significant STI-change outcomes.^23-25

Although the interventions described above varied in their content, of course, the prototypic intervention was a small group program in which peer opinion leaders would both participate in and lead the groups, and topics discussed included education on risk triggers and self-management, condom use, and peer support.^26-30 These types of interventions were highly successful at changing HIV risk behaviors (e.g., by improving correct and consistent condom use).^24,31 While also heavily reliant on peer opinion leaders, some interventions operated more at the community level, attempting to inform, motivate, and empower entire communities at the same time.^21,32

CDC was also interested in developing behavioral interventions during this time period, most especially as behavior change counseling might be coupled with HIV testing. In 1998, CDC published the findings from Project RESPECT, which sought to determine the effectiveness of providing counseling in conjunction with HIV testing as a means to modifying HIV-related risk behaviors and reducing non-HIV STIs (as a proxy for reducing HIV incidence).³³ Project RESPECT found that pre- and post-test counseling could change HIV-related risk behaviors and incidence of non-HIV STIs among HIV seronegative persons attending sexually transmitted disease clinics in several U.S. cities.³³ Marrazzo and colleagues discuss the complex array of ensuing studies that examined the effects of counseling as it relates to HIV testing.²⁵

These are but a few examples of the types of behavioral interventions developed for HIV prevention. Other types of successful interventions have included couples counseling³⁴ and community empowerment interventions.³⁵ Also, over time, there was more attention paid to developing HIV prevention programs that served PLWH to avoid transmission to sex and drug injection partners, as well as to emphasize benefits from strong linkages to HIV care and ancillary services.^25,36 This reflects in part CDC's focus on HIV treatment as prevention, as well as their focus on prevention efforts to disrupt transmission from PLWH. In fact, CDC has labeled this approach as "high impact" HIV prevention.³⁷

A crucial development in this line of behavioral intervention research was the development of CDC's Research Synthesis Project, which saw the methodological review of numerous studies, and, as of 2014, the identification of 51 "best" evidence and 33 "good" evidence interventions (where the adjectives in quotations are defined according to the level of empirical evidence available in the literature for each intervention).³¹ CDC then selected some interventions for further dissemination to the field and implemented the "DEBI" (for "diffusing evidence-based interventions") project. The DEBI project saw the packaging of key evidence based interventions into manual and training course form, so that the capacity of interested service delivery organizations could be built to deliver these interventions.^37,38

Social Determinants and Structural Interventions

Another important era in the development of behavioral and social interventions was the expanding recognition in the late 1990s and early 2000s^39,40 that social determinants of health (such as living in wartime, impoverished and/or socially inequitable situations) also were related to heightened HIV prevalence. CDC and HUD (the U.S. Department of Housing and Urban Development) were among the first Federal agencies to attempt to construct structural interventions to address these social determinants by fielding a major study of housing provision to homeless and unstably housed persons as an HIV prevention intervention.⁴¹ In "as-treated" analyses, the study found the provision of housing to actually impact the level of viral load among clients living with HIV.⁴² Further, the cost per quality adjusted life year (cost per QALY) saved by this intervention was $62,493 in 2005 year dollars, indicating a reasonably good level of cost-effectiveness for the provision of this resource-intensive program.⁴³ Most recently, CDC has issued a report examining the social determinants of health for PLWH in a number of jurisdictions in the United States.⁴⁴

Another critical example of an evidence-based structural intervention is sterile syringe exchange programs in which persons who inject drugs (or someone acting for them) can exchange syringes that may contain HIV (and other infectious diseases) for sterile injection equipment.^45,46 Social scientists were involved in studying and establishing the evidence base for syringe exchange programs, most notably in studies done at Yale and the University of California, San Francisco in the 1990s with the collaboration of CDC.^47-52 In summary, they found that syringe exchange programs did lead to a decrease in HIV transmission among program participants and their partners and did so in a highly cost-effective manner (the economic argument of which was recently confirmed by Nyugen et al.).⁵³

Behavioral Factors in Care and Treatment

The behavioral sciences can also play an important role in HIV care and treatment.²⁵ Relatively recent ground-breaking research suggested that widespread early initiation of antiretroviral therapy (ART) could substantially reduce the transmission of HIV.^13,54,55 This realization changed the landscape of HIV prevention and led to an increase in focus on access to HIV care and treatment services as a tool for reducing HIV transmission. There are many behavioral factors related to successfully navigating the treatment cascade in order to realize the optimal treatment and prevention effects of ART. Individuals must be tested for HIV and receive the result of their test, have an initial HIV care appointment, engage in ongoing HIV care, be prescribed and adhere to ART, and finally, achieve and maintain viral suppression.⁵⁶ Movement through these steps is not always linear, however, and many individuals cycle in and out of care.^57,58

Behavioral and social science interventions make key contributions at each of these steps. CDC's National HIV Behavioral Surveillance system has been critical for understanding the level, locale, and determinants of undiagnosed HIV seropositivity in a number of jurisdictions in the United States.^59,60 In order to promote the potential of HIV treatment as prevention, CDC has emphasized not only linkage and retention in care, but also HIV testing so that one can learn their HIV serostatus in the first place. This has largely taken the form of CDC advocating for universal, clinic-based HIV testing for 13 to 64-year-old persons, with persons in the highest risk communities testing at least once per year.⁶¹ It is recognized however that not all testing will occur in clinical settings, as some members of some communities currently have limited or no access to clinical care. Therefore, community-based HIV testing programs (such as HIV testing provided in concert with syringe exchange programs, or venues such as "house balls" in transgender communities) can serve a critical function in increasing awareness of serostatus.⁶² Especially in community-based testing, social networking approaches can be key in efforts to reach not just one person at risk of infection (or who is undiagnosed and living with HIV), but the entire network of sexual partners and/or drug injection partners of the index person living with HIV.⁶³

Once a PLWH is aware of his or her status, he or she must attend HIV medical appointments. Behavioral intervention strategies such as motivational or strengths-based counseling, information and education about HIV care, peer navigation, accompanying clients to medical appointments, and appointment coordination have been found to increase linkage to and retention in care among PLWH who are newly diagnosed or out of care.^25,64,65

Adherence to HIV medication is a health behavior that is vital to the success of HIV treatment for the health of the infected person and for prevention of onward transmission. A handful of idence-based ART adherence interventions have successfully increased ART adherence among a variety of populations, including clinic patients, drug users, and men who have sex with men. These interventions share common components, such as skills-building around medical adherence, addressing barriers to adherence and problem solving, communicating with providers, and building social support.⁶⁶

Behavioral scientists are building the evidence base for successful interventions that facilitate viral suppression, researching the process of translating these interventions into practice in new locations and with various populations, and testing new innovative intervention models. In addition, behavioral scientists are conducting important research to better understand the factors associated with successfully (or unsuccessfully) engaging in the steps along the spectrum of HIV care and treatment. For example, work by Lo and colleagues identified the critical role that ancillary services—such as receipt of mental health care, drug assistance, food/nutrition, and transportation—play in utilization and retention in care.⁶⁷ Keruly and colleagues found that factors such as age, race/ethnicity, sex, CD4 cell count, insurance status, and number of missed clinical visits were predictive of highly active antiretroviral therapy (HAART) use.⁶⁸ This line of research helps to identify the populations at greatest risk for not fully engaging in HIV care and treatment and suggests potential areas where interventions and policy could intervene.

The behavioral and social sciences are also directly relevant to the NHAS goal of reducing health disparities. Traditional methods of infectious disease epidemiology focus on patterns of HIV disease. These epidemiological investigations need the behavioral and social science information to make them optimally useful for the design of treatment and prevention strategies. CDC has made a major priority of carrying out behavioral surveillance studies to complement more traditional epidemiologic investigations. Their National HIV Behavioral Surveillance System (NHBSS)^69,70 examines risk behaviors and epidemiologic contexts among men who have sex with men (defined in terms of behavior rather than in terms of gay or bisexual identity), persons who inject drugs, and heterosexual women at heightened risk of HIV infection (one population per year on a rolling 3-year basis).^69,70 This use of behavioral methods in surveillance studies has led to critical insights. For example, social scientists in Baltimore have used surveillance studies to better understand disparities among vulnerable populations, gather data on risk behaviors, and directly monitor and plan for HIV prevention.^59,60 Maulsby and colleagues used surveillance data to identify disparities in HIV testing-related behaviors and predictors of undiagnosed seropositivity among men who have sex with both men and women (MSMW).^59,60 They found that a range of partnership characteristics contributed to undiagnosed seropositivity among MSMW, highlighting the need for programs that address the unique partnership dynamics of this population. Behavioral scientists at Johns Hopkins have worked with administrators at the Maryland Department of Health and Mental Hygiene to determine alignment between surveillance indicators and local NHAS HIV prevention goals and to establish procedures to facilitate the future use of surveillance data in local HIV program planning and policymaking.⁷¹

In summary, the behavioral and social sciences have made critical contributions of direct relevance to achieving the goals of the NHAS, and we acknowledge that our brief review here portrays only some of the impact findings in this arena. Now, we turn to some emerging issues in the application of the behavioral and social sciences to the NHAS, and we discuss economic and implementation science aspects of these interventions, before describing how the behavioral and social sciences can help to inform future goals that may be part of the next NHAS.

Emerging Issues in Behavioral and Social Aspects of HIV

NIH HPTN trial 052 provided strong evidence that HIV treatment that successfully suppressed viral load actually served to substantially decrease the transmission of HIV to seronegative partners.^13,14 Because of this landmark finding, much subsequent attention has been paid to HIV "treatment as prevention." Initially, such biomedical findings led to coining of the term "combination prevention" in which clients were to receive the very best evidence-based behavioral and biomedical interventions for HIV prevention and care. However, over time, some have emphasized treatment as prevention to the exclusion of behavioral interventions (a phenomenon we elsewhere called "substitution prevention").^16,72 We have argued that what is truly needed is "synergistic prevention" in which biomedical and behavioral interventions are offered in a complementary manner so that clients receive the best mix of behavioral and biomedical interventions in a manner that truly results in a decrease in HIV incidence, with the whole being more than the sum of the parts.^16,72

Other recent studies have shown that HIV drugs taken by HIV seronegative persons as "pre-exposure prophylaxis" (or PrEP) can substantially reduce the probability of someone contracting HIV from a person living with HIV.²⁵ PrEP has been controversial in that on the one hand the prevention potential of the intervention is quite strong, but on the other hand, PrEP effectiveness is very dependent on high levels of adherence, can be highly expensive, and may lead to the decrease of other modes of prevention.⁷³ CDC, WHO (the World Health Organization), and other bodies have now recommended PrEP in relatively limited but important circumstances (illustrations of such circumstances include persons at heightened risk for HIV infection due to >2% background HIV seroprevalence, a recent sexually transmitted disease diagnosis, sharing of drug injection equipment, or needing to frequently utilize post-exposure prophylaxis).^25,74-76

Economic and Implementation Research Issues

As noted previously in this chapter, a number of the behavioral and structural HIV prevention interventions described here have been subjected to economic evaluation and found to be cost saving or cost effective when compared with other interventions in medicine and public health.^43,77,78 One possible exception is that of PrEP, an intervention for which the cost-effectiveness analytic results vary widely with the variation driven largely by the HIV seroprevalence of the community under study.^79,80

Not all jurisdictions have the resources necessary to deliver all useful, cost-effective interventions to scale to all who may benefit from them. Therefore, several recent studies have focused on determining the most impactful (in terms of HIV prevention) use of available resources. For example, two recent studies have examined how best to avert the maximum number of HIV infections given limited resources for the Baltimore-Towson metropolitan statistical area (MSA) and for the State of Iowa.^81,82 A common theme in these resource allocation studies is that because HIV prevention funds are so limited, very hard choices about maximizing impact with insufficient resources must be made. another type of economic analysis attempts to estimate the overall unmet HIV prevention, care, and/or housing needs among a particular population. For example, we recently conducted a study to determine the overall unmet HIV prevention, care, and housing service needs among black men who have sex with men in the United States.⁸³

Interestingly, the NHAS makes no mention of the costs that would be incurred by complete implementation of the strategy or its return on investment. We made estimates of the costs and return on investment in 2010 and updated these estimates again in 2012.^84,85 Such analyses provide quantitative estimates of the level of investment that would be required to meet the NHAS 2015 goals and what might be expected at current resource levels. We found that while the programmatic costs of meeting all goals of the NHAS would be substantial, such an investment would not only change the course of the HIV epidemic in terms of reductions in HIV incidence and transmission rates and improvements in access to care, it would do so in a manner that would be considered cost effective by traditional economic evaluation standards.

Goals for 2016 and Beyond

Our previous analyses of the costs and consequences of the NHAS concluded that it was still possible to meet the goals of the NHAS if a substantial investment in new and/or redirected public and/or private sector funds had been made. It would have been necessary to make this investment very rapidly,^84,85 since significant resources would be needed in fiscal years 2013 and 2014 (this is because investment in one fiscal year is unlikely to impact program delivery until later that year or the next year, with disease-specific impacts 1 or more years later). Unfortunately the FY2013 and FY2014 Federal appropriations processes did not yield the level of increased or redirected resources necessary to make the major move toward scale-up of services needed to achieve the NHAS 2015 goals.⁸⁶ Therefore, we recently published an article arguing that the full achievement of the NHAS goals is probably now out of sight at this point due to lack of sufficient investment (though data on some key indicators lags).⁸⁶ We argued further that even if the 2015 goals are seemingly out of reach at this point, earlier mathematical modeling could be used to productively inform possible NHAS goals for 2016 through 2020 (assuming there would be another NHAS for future years). These suggested goals are listed in Table 2.

Table 2. Proposed 2020 goals for a new National HIV/AIDS Strategy (NHAS) for the United States

Source: Reprinted from Holtgrave DR. Development of year 2020 goals for the National HIV/AIDS Strategy for the United States. AIDS Behav 2014;18(4):638-43. With kind permission from Springer Science and Business Media.
Notes: All four section headings are quoted exactly as presented in the Federal National HIV/AIDS Strategy issued in July 2010 (http://www.whitehouse.gov/sites/default/files/uploads/NHAS.pdf); the goals in each section are newly proposed or modified here.
Key: CDC = Centers for Disease Control and Prevention; HIV = human immunodeficiency virus; HRSA = Health Resources and Services Administration; NHAS = National HIV AIDS Strategy; PLWH = people living with HIV.

What is immediately noticeable is that we do not attempt to "kick the can" down the road and simply repeat the 2015 goals. Rather, we crafted 2020 goals that would seem to be epidemiologically attainable with reasonable investment in needed services; in other words, these goals are feasible if the appropriate level of investment is made. These draft, possible goals are meant to inform discussion, and we believe behavioral and social scientists have a great deal to contribute to the crafting of the next generation of the NHAS.

Conclusions

The behavioral and social sciences have made significant contributions to the efforts to prevent and treat HIV in the United States. Now is a time of change in that new biomedical findings have caused a sea change in how HIV prevention and treatment are viewed in the United States; this challenges the behavioral and social sciences community to consider new target behaviors, modernize intervention content for relevance, further expand to include the addressing of social determinants of HIV, and fully embrace methods of implementation research that include consideration of the costs, consequences, and setting of national HIV/AIDS goals. Despite the unfolding history of the HIV epidemic in the United States, the behavioral and social sciences community will have further key roles to play, so that one day soon we might actually see the elimination of HIV in the United States.^87-89

Implications for Practice

Woven throughout the sections above, we have highlighted a number of ways in which the behavioral and social sciences have and can still impact HIV prevention and care practice. This is very well illustrated in the recent International AIDS Society-USA (IAS-USA) publication on combination HIV prevention in an era of treatment advances.²⁵ This IAS-USA panel comprised a highly interdisciplinary group of behavioral and social scientists, physicians, and epidemiologists. They sought to determine the optimal evidence-based combination of biomedical and behavioral interventions that clinicians could use to prevent HIV infection among their patients or onward transmission of HIV from their patients living with HIV. The complete recommendations can be found in the article online (free access at http://jama.jamanetwork.com/article/aspx?articleid=1889145. here we present some of the key behavioral and social elements of the recommendations:

• HIV risk screening and counseling that is evidence-based, effective, and meets client needs but is not so intrusive in the clinical practice as to be a barrier to routine HIV screening.
• Brief evidence-based risk reduction interventions suitable for use in the clinical setting for HIV seronegative clients at ongoing risk for HIV infection (including a complementary mix of behavioral risk reduction services and access to pre-exposure prophylaxis).
• Evidence-based HIV prevention services for patients living with HIV infection.
• Evidence-based supportive services to enhance linkage to, retention in, and adherence to HIV care and treatment.

A theme across these clinical practice recommendations for prevention is the synergistic combination of evidence-based behavioral and biomedical interventions. Of course these recommendations were focused on what clinicians can do, but many of the recommendations are salient at the population level as well and could be utilized by health departments and community- based service providers. Still, some structural interventions noted above are much more likely to be implemented at the population level, and these would include housing services, stigma prevention/reduction campaigns and modernization of HIV-related laws, and syringe exchange services. Further, the economic analyses described above also provide actionable policy recommendations in terms of resources needed to address unmet needs and what the likely epidemiologic and fiscal consequences of such investments would be. In particular, such modeling analyses give us a glimpse into the future as to whether or not the goals of the NHAS will be realized at the current levels of investment.

Implications for Research

Also embedded in the section above are many clear implications for needed future research, a few of which we underscore here. NIH frequently updates a comprehensive agenda for behavioral and social science research focused on HIV. It is beyond the scope of this section to replicate such a comprehensive research agenda; instead, we highlight here just a few areas in need of rapid attention.

• Additional testing of prevention "bundles" of behavioral and biomedical interventions using state of the art implementation science methods (rather than testing one intervention at a time).
• Rapid turn-around analyses to inform the selection of input parameters for policy modeling exercises (for example, there is scant literature available on the costs and effects of partner notification services, but such services are important to consider in resource allocation analyses; additional, rapid, empirical guidance on such parameters would be directly and immediately useful).
• Rapid turn-around studies to bolster evidence-based interventions to improve HIV care linkage and retention (while linkage and retention in care are absolutely critical, the number of intervention studies in this arena is still relatively small).
• Methods to more quickly estimate key metrics needed to monitor NHAS progress (e.g., while the goals of the NHAS run through 2015, the most recent HIV incidence estimate for the United States from CDC is for the year 2010).
• Additional mathematical analyses to inform setting of NHAS 2020 goals (while we have published some such analyses, the mathematical modeling literature is always well served if there are multiple modeling exercises done by independent teams to determine if the overarching policy recommendations from different analyses are similar).
• Rapid turn-around mixed methods studies to help us understand what prevention and care services are needed to help stem the trend of new HIV infections among the populations most disproportionately impacted (with a special urgency on studies related to young black gay men).

A theme that runs throughout these research recommendations is that they tend to focus on matters of community need, scale up, implementation evaluation, and health services research; this is because we already have many evidence-based HIV prevention and care tools at our disposal, yet we may not always be employing them properly or with the right intensity. These are empirical matters that can be informed by rigorous yet urgent study.

Acknowledgments

The opinions presented in this chapter are those of the authors and may not necessarily represent the position of the Agency for Healthcare Research and Quality, the National Institutes of Health, or the Department of Health and Human Services.

Authors' Affiliations

David R. Holtgrave, PhD, Professor and Department Chair; Cathy Maulsby, PhD, Chris Adkins, MSW, Laura W. Fuentes, MM, Department of Health, Behavior & Society; Johns Hopkins Bloomberg School of Public Health.

Address correspondence to: David R. Holtgrave, PhD, Department of Health, Behavior & Society, Johns Hopkins Bloomberg School of Public Health, 624 N Broadway, Baltimore, MD 21205;email david.r.holtgrave@jhu.edu.

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	David Holtgrave, PhD, is a professor and Chair of the Department of Health, Behavior and Society at the Johns Hopkins Bloomberg School of Public Health. He also holds joint appointments in the Johns Hopkins schools of medicine and nursing. Since 1991, Dr. Holtgrave's work in the field of HIV prevention has focused on the effectiveness and cost-effectiveness of HIV prevention interventions and the translation of those study findings to HIV prevention policy. He serves as vice-chair of the President's Advisory Council on HIV/AIDS. Previously, Dr. Holtgrave was a professor at the Rollins School of Public Health at Emory University. He also served as director of the Division of HIV/AIDS Prevention—Intervention Research and Support at the Centers for Disease Control and Prevention and was on the faculty at the Center for AIDS Intervention Research at the Medical College of Wisconsin.
	Cathy Maulsby, PhD, is an Assistant Scientist in the Department of Health, Behavior and Society at the Johns Hopkins Bloomberg School of Public Health. Her research focuses on HIV prevention among underserved populations, including men who have sex with men and women and minority men who have sex with men. She currently is the principal investigator and director of evaluation for the national evaluation of Access to Care, an HIV prevention and care initiative funded by AIDS United that aims to improve the continuum of care for individuals who are out of care or in danger of falling out of care.
	Chris Adkins, MSW, is a Senior Research Coordinator in the Department of Health, Behavior and Society at the Johns Hopkins Bloomberg School of Public Health. His work focuses on Lesbian, Gay, Bisexual, and Transgender (LGBT) health issues, particularly with regard to intersectionality and the life course perspective, as well as the facilitators and barriers to HIV medical care. He also serves on the Board of Directors of the Gay, Lesbian, Bisexual, and Transgender Community Center of Baltimore (GLCCB), where he works on HIV prevention and interventions with youth at-risk of homelessness.
	Laura Fuentes, MM, is a key leader in the Lerner Center for Public Health Promotion in the Department of Health, Behavior and Society at the Johns Hopkins Bloomberg School of Public Health. Her research currently focuses on the evaluation of health promotion campaigns in the areas of smoking cessation and weight loss. She also serves as the program director for an ongoing collaboration between the Department of Health, Behavior and Society and the Monday Campaigns, a New York- based nonprofit organization committed to health promotion activities on the first day of the week.