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FOR 25 YEARS, IT WAS AXIOMATIC IN THE HIV
PREVENTION FIELD TO STATE THAT RISK REDUCTION
BEHAVIOR CHANGE WAS THE ONLY AVAILABLE
MEANS TO PREVENT THE DISEASE
From the late-1980s forward, public health efforts to prevent the transmission of
HIV infection rested almost fully on helping persons make and sustain changes in
their sexual and drug use risk practices.
This gave rise to a large body of research that developed and evaluated the
effectiveness of behavioral, social, and structural interventions designed to r educe
the prevalence and frequency of high-risk behavior practices at various levels:
• Individual level
• Small group level
• Social setting level
• Social network level
• Community level
• Structural levels
• Societal and macro levels
BEHAVORIAL, SOCIAL, AND STRUCTURAL
INTERVENTIONS HAVE BEEN CONVINCINGLY SHOWN
TO REDUCE LEVELS OF BEHAVIOR RESPONSIBLE FOR
TRANSMITTING AND CONTRACTING HIV INFECTION
Collectively, decades of research has established that theoretically-based, contextually-
tailored, sufficiently intensive interventions that motivate behavior change help people
develop skills for behavior change, and reinforce behavior change efforts can reduce sexual
and substance use risk practices even in populations where risk is longstanding and high.
Effect sizes have often been moderate to high, reflecting risk behavior declines by one-third
in many intervention outcome trials.
Evidence of effects of these interventions on HIV incidence outcomes in behavioral trials
has been more elusive:
• Unlike large biomedical trials, behavioral intervention studies have rarely been
powered with samples large enough to detect effects on HIV incidence.
• Interventions have rarely been compared to inert placebo controls.
• Behavior change effects are not always well-maintained.
MANY IN THE PUBLIC HEALTH FIELD
HAVE PERSUASIVELY ARGUED THAT INTERVENTIONS
TO PROMOTE RISK REDUCTION HAVE AVERTED
A MUCH WORSE HIV EPIDEMIC
Holtgrave and others have modeled what would have been the HIV
epidemic picture in the United States and the world without the
development and deployment of effective HIV prevention behavior change
interventions, and the picture would have been far worse.
HIV incidence and prevalence has declined in many populations from
earlier levels, including drug users and MSM in the United States, with
the exception of African American MSM.
Yet, annual HIV incidence in the US has remained at a 50,000 plateau for
many years.
The HIV prevention intervention field became, in my opinion, fatigued
and uncertain of where to go next by the early 2000s.
BEGINNING IN THE LATE-2000S, SEVERAL SETS
OF LARGE TRIALS ESTABLISHED THE EFFICACY
OF BIOMEDICAL INTERVENTIONS TO PREVENT
AND PROTECT AGAINST HIV TRANSMISSION
• Male circumcision in the context of generalized heterosexual epidemics
• Treatment-as-prevention (viral suppression among PLH as a result ofantiretroviral treatment), HPTN-052
• Pre-exposure prophylaxis (ART regimens as a protection againstcontrac-ting HIV among high-risk uninfected persons, PrEP) (iPREX)
• Mixed picture to date for vaginal and anal microbicides
Although biomedical in nature, these developments have also reinvigoratedthe HIV behavioral, social, and structural intervention fields.
ALTHOUGH THERE IS UNEQUIVOCAL EVIDENCE OF
THE EFFICACY OF TREATMENT-AS-PREVENTION AND
PREP IN CLINICAL TRIALS, THESE NEW
PARADIGMS CAN ACHIEVE PUBLIC HEALTH IMPACT
ONLY IN THE CONTEXT OF ACCOMPANYING
BEHAVIORAL INTERVENTIONS
In the case of PrEP, protective outcomes were strongly dependent on levels of
consistent medication-taking adherence among high-risk uninfected persons
In at least some microbicide trials, lack of effect appears due to poor
adherence as well as product and formulation limitations
In the case of treatment-as-prevention (perhaps the most promising and
feasible biomedical prevention model), public health deployment and public
health effectiveness of biomedical HIV prevention depends on better behavioral
interventions employed at multiple junctures and with multiple aims.
GARDNER’S HIV TREATMENT CASCADE TO VIRAL
SUPPRESSION HAS BEEN WIDELY ADOPTED
TO CONCEPTUALIZE STEPS TO ACHIEVE
TREATMENT-AS-PREVENTION OUTCOMES
Positive Serostatus Knowledge
Linkage to Care
Retention in Care
ART and Viral Suppression
Undetectable Viral Load
THE CASCADE IS ALSO A USEFUL HEURISTIC FOR IDENTIFYING
KEY POINTS FOR BEHAVIORAL INTERVENTION
Cascade Point Interventions
Postitive Serostatus Knowledge • Interventions to increase routine testing
policy adoption
• Interventions to increase frequent and
regular testing
• Interventions to detect acute infection
Linkage to Care • Interventions to improve care linkage
• Systems-level interventions
Retention to Care • Early intervention when care appointments
are missed
• Community interventions that can reach
out-of-care PLH
ART and Viral Suppression • Adherence interventions
• Interventions to sustain adherence
Undetectable Viral Load • Life course interventions
FOR TREATMENT-AS-PREVENTION TO WORK
ON A PUBLIC HEALTH SCALE, BETTER BEHAVIORAL
AND SOCIAL SCIENCE-BASED INTERVENTIONS ARE NEEDED
AT EACH JUNCTURE
At this stage in the HIV prevention field, biomedical approaches hold great
promise but this potential can only be realized if health actions among PLH
become recognized as behavior and if behavioral intervention research is directed
towards these health actions.
“Implementation science” has been used to describe what is needed. This needs to
squarely address not just the implementation process but also the development of
interventions based on sound behavioral and social science.
Some junctures on the cascade are receiving substantial attention:
• Encouragement of testing
• Treatment adherence (at least short-term)
• Linkage-to-care
Other critical junctures and issues remain understudied.
KNOWLEDGE OF ONE’S HIV+ SEROSTATUS IS
FUNDAMENTAL TO ENTERING TREATMENT,
BUT THERE IS STILL A LONG WAY TO GO
TO ACHIEVE EARLY DETECTION
Campaigns to promote testing are one of the oldest HIV prevention
strategies, but about 20% of Americans with HIV still do not know it.
Most gay men (and many injection drug users) have been tested at some
point, and most people testing positive previously had a negative test.
Testing may too often be viewed as a one-time or occasional need, and
regularity of testing—frequent testing—needs to become an explicit goal
for MSM, substance users, those with STD histories, and others at
continuing high risk.
Interventions that emphasize frequent, regular testing are needed at levels
of social networks, community campaigns, and among service pr oviders.
STRIDES ARE BEING MADE IN DEVELOPING STRATEGIES
TO LINK NEWLY-DIAGNOSED PLH TO CARE, BUT A NEGLECTED
POPULATION IS THE MUCH LARGER NUMBER OF PLH
IN THE COMMUNITY WHO HAVE LONG BEEN OUT OF CARE
Many of the 50,000 Americans newly-diagnosed with HIV will benefit from new care linkage
initiatives.
However, CDC data show that almost half of persons in the US awar e that they are HIV+ have
not received any medical care for their disease in the past 6 months or longer, some never.
These 500,000 Americans will not be in linkage programs, will not benefit from care, and will
greatly limit the public health impact of treatment-as-prevention models until they are
engaged or re-engaged into care systems.
Big behavioral and social science research questions:
• Who are in this very large pool of out-of-care PLH in the community?
• Why are they not in care?
• How can they be reached in the community?
• How can they be engaged to enter care?
Community and social network intervention methods seem well-suited for interventions
designed to reach out-of-care PLH in the community.
ANOTHER EARLY DETECTION/LINKAGE QUESTION
THAT HAS RECEIVED VERY LITTLE ATTENTION
INVOLVES GETTING PERSONS WITH ACUTE INFECTION
QUICKLY INTO CARE
During the first weeks following seroconversion, persons with newly acquired
(acute) HIV infection (AHI) have very high viral load and are very likely to transmit
the disease to others. A greatly disproportionate number of infections are
transmitted by newly-infected persons during their brief AHI phase, in the US and
abroad.
Persons with AHI are critical but elusive given the brevity of their superinfectious
window. However, influenza-like symptoms usually accompany and can signal AHI.
Health and testing providers are in a position to diagnose AHI early and to avert
many onward transmissions, but behavioral interventions with pr oviders, in gay
communities, and in substance user communities to bring persons with AHI to
testing and care:
• Community-level interventions to heighten awareness of AHI symptoms
• Interventions with providers to heighten awareness of possible AHI
RETENTION IN CARE IS AS CRITICAL
AS LINKAGE BUT HAS RECEIVED MUCH LESS
INTERVENTION ATTENTION
Systems-level interventions coupled with close care management and
accessible, low-threshold care have shown promise for improving the linkage
of newly-diagnosed PLH into care. However, cascade analyses at national and
state levels show that long-term treatment retention over time becomes much
lower. If persons leave care, by definition they will not benefit from care.
Factors that predict poor care retention consistently include substance abuse,
life chaos, housing instability, and mental health disorders.
The field urgently needs interventions focused on maintaining care retention.
These interventions either must address drop out risk factors or be robust
enough to work even against the backdrop of these barriers.
ADHERENCE FOR THE LONG HAUL
Medication nonadherence has been the factor limiting efficacy in almost all trials of
ART regimens used for treatment, prevention, and protection.
Trials such as HPTN-052, iPREX, and others did not ignor e adherence. All of the
trials counsel patients at the start of treatment and points of contact later. Still, a high
proportion do not adhere sufficiently to derive maximum benefit.
Medication non-adherence is not a new problem nor is it limited to ART for HIV.
However, even modest nonadherence poses greater threat than in many other health
areas.
Increased attention to new paradigms for improving sustained adherence is critical if
the potential of ART for treatment, prevention, and protection is to be realized.
Promising paradigms include:
• Technology linked to real-time medication taking
• Sustained interventions for sustained effects
• Mobilizing social and normative supports for adherence
• Addressing concurrent life issues that jeopardize adherence
LIFE COURSE PERSPECTIVES
IN CARE AND PREVENTION
Due to treatment advances, HIV infection is no longer primarily a disease of
youth, and life course perspectives for treatment and adherence are needed.
HIV prevention and adherence research has taken very short-term
perspectives to intervention and effect assessment.
We still know very little about how to intervene to produce long-term change
whether in risk reduction, treatment engagement, and ART adherence. Very
long-term effects are rarely measured.
Although HIV infection produces neuropsychological impairment greater
than the normal effects of aging, interventions to promote adherence in older
adults living with HIV remain understudied.
Greater attention to life course HIV social and behavioral issues is needed.
IN AN ERA OF NEW APPROACHES TO HIV PREVENTION
BUT LIMITED FUNDING, RESEARCH TO GUIDE
RESOURCE ALLOCATION DECISIONS IS ESSENTIAL
Cost-effectiveness research has always sought to determine the public health
benefits that would accrue through the adoption of various HIV prevention
interventions.
Especially with the prospect of decreased public health funding but also the
emergence of promising new prevention strategies, a new set of researchable
questions has emerged. Examples include:
• If prevention resources were directed toward treatment rather than
traditional risk reduction prevention, what would be the effect on HIV
incidence (assuming various realistic scenarios of treatment coverage
and adherence)?
• At what points on the HIV treatment cascade will expansion of
resources have the greatest effect on future incidence?
THE LEVELS OF INTERVENTION MODELS
PREVIOUSLY USED ONLY FOR HIV RISK REDUCTION
CAN GUIDE THE FIELD’S THINKING ABOUT
INTERVENTIONS NEEDED TO IMPLEMENT NEW
BIOMEDICAL HIV PREVENTION APPROACHES
Although the behavior change targets of cascade-related goals are
different than those of risk reduction interventions, revisiting
conceptions of levels of intervention may prove useful for guiding
research into new challenges related to biomedical prevention.
• Individual level
• Small group level
• Social setting level
• Social network level
• Community level
• Structural levels
• Societal and macro levels
ALTHOUGH THERE ARE IMPORTANT NEW OPPORTUNITIES
FOR BEHAVIORAL SCIENCE INTERVENTION RESEARCH
RELATED TO BIOMEDICAL ADVANCES, BALANCE
MUST BE MAINTAINED BETWEEN ESTABLISHED
APPROACHES AND NEW OPPORTUNITIES.
As the field pursues new agendas to move biomedical advances to scalable
and effective applied prevention strategies, it is important to continue to
refine interventions to reduce high-risk behavior.
HIV prevention needs will not be met by biomedical prevention alone.
Coverage and adherence will always be imperfect, and risk behavior
reduction will always remain a critical objective.
Failure to also pursue risk behavior reduction interventions targeting those
populations with highest incidence will result in more infections, not fewer.
Combination behavioral, social, and biomedical prevention represents the
most promising strategy for high-impact outcomes.