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Challenges and Opportunities to evaluate Combination Prevention. Marie Laga Institute of Tropical Medicine Antwerp Belgium. Challenges to evaluate combination Prevention. Measuring HIV incidence The complexity of Prevention programs with long causal pathways - PowerPoint PPT Presentation
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Challenges and Opportunities to evaluate Combination Prevention
Marie Laga Institute of Tropical Medicine
AntwerpBelgium
Challenges to evaluate combination Prevention
1. Measuring HIV incidence
2. The complexity of Prevention programs with long causal pathways
3. The scarcity of monitoring data and process evaluation of current Prevention programs
4. Interpreting National HIV trends and attributing changes to Prevention programs
5. The evaluation methods to establish program effectiveness
Measuring change in HIV incidence
• Cohort studies• Lab methods ( BED, STARHS,..)• Proxy’s: prevalence in 15-24y • Estimating incidence from successive
prevalence survey’s• Modelling: EPP, Asian Epidemic model, and
more recent methods
None ideal, most progress with modellingUrgent need to develop HIV incidence assay
The complexity of the combination prevention programs
need for Program impact PathwayHow is the program expected to reduce HIV incidence?
• Spelling out the different steps and make the connections explicit […if..then…]
• Attention to include underlying contextual factors resulting in long and complex causal chains
• Balance between simplifying reality and not being simplistic
• Need for guidelines on methodology and more practical examples
University of Wisconsin-Extension, Program Development and Evaluation
Statewide Tobacco Control: Smoke-free environmentsOUTCOMES
Mgrs of public areas/events
Coalition
Time
Money
Partnersincluding youth
Research and best practices
Organize and implement Smoke-free campaign
Organize and implement strategy for treating tobacco addiction
Public
Youth
Organize and implement strategy to prevent youth tobacco use
Influential others
Demonstrations of support
Reduction in tobacco use and exposure
Change in knowledge, attitude, motivations
Increased knowledge of availability of cessation resources
Increased use of cessation resources
Increased # of quit attempts
SF policies implemented, enforced
Elected officials
Tobacco users• Adults• Youth
Worksite contacts
Parents, schools, etc.
Changes in attitudes and motivations
Increased # of prevention programs, policies adopted, enforcement
Changes in awareness, knowledge and attitudes about SF
Residential owners, mgrs
Increased commitment, support, demand for SF environments
Policy makersIncreased commitment to eliminate access Retailers
Change in behaviors
Poor monitoring of the current prevention response
Is the program implemented according to plan? Coverage? Reach? Quality?
• Data not collected• Data not made available or not used• Coverage estimates: definition of numerator and
denominator (seize estimates of hard to reach population; Human rights issues )
• Definition of minimum quality standards• Missing baselines
7
Understanding National TrendsAdjusted HIV prevalence* among ANC women, by year,
1996-2006-CAMBODIA
1.9
0.9
2.22.42.9
2.5
1.8
2.3
2.72.8
2.62.4
1.81.5
1.3
2.0
2.2
2.8
0.0
0.5
1.0
1.5
2.0
2.5
3.0
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Per
cen
t
Adjusted, weighted data Adjusted, weighted data smoothed with EPP
Source: Analysis and Advocacy (A2) Thailand Team, Pattaya presentation to ASAP meeting, January 2006.
Understanding National TrendsEstimated number of new HIV infections in Thailand 1988-2008
HIV surveillance is critical data source to evaluate the 100% condom program
0
5
10
15
20
25
30
19891991
19931995
19971999
20012003
Pe
rce
nt
HIV
po
sit
ive
ANC Male STD Direct sex worker Indirect sex worker Military conscripts
Source: Bureau of Epidemiology, Ministry of Public Health Thailand
Evidence of behavioral change in Thailand
Source: Relationships of HIV and STD declines in Thailand to behavioral change: A synthesis of existing studies, UNAIDS 1998
Understanding National trendsGeneralised epidemics
Source: UNAIDS Report on the global AIDS epidemic, 2008
Understanding National Trends: Impact of Prevention
The example of Zimbabwe
1980 1985 1990 1995 2000 2005 20100
2
4
6
8
10
Year
HIV
inci
de
nce
(p
er
10
0p
yar)
Natural decline in incidence ~ 1990
Accelerated decline in incidence, due to behaviour change: ~ 2000
Source: Hallett, Gregson, Gonese, et al., Epidemics, 2009
Evaluation of Public Health programs
Type of evidence
Type of statement Compared to what
Adequacy The expected change occurred (but no causality)
-No control group -Predefined criteria, or absolute or incremental value
Plausibility Program seemed to have effect over & above external influences based on a step by step ruling out of other confounding factors
-A non-random control group (historical, external, internal, simulated)
Probability -The program has an effect -(P<x% that the difference between program & non-program were due to confoundig / bias)
-Randomised control group or cluster
Ref: Habicht et al
• Teacher-led, peer-assisted in- school sexual and reproductive health education
• Youth-friendly sexual and reproductive health services
• Community-based condom promotors and distributors
• Community-wide activities, to create a supportive environment
The evaluation results• no impact on HIV and STI rates
after 3 and 8 years
• In and out of school youth• Parents and community
stakeholders improving their knowledge and changing their attitudes to adolescent reproductive health issues as well as improving their communications skills
• Clinic staff to improve accessibility and acceptability of rural clinics to young people
The evaluation results• no impact on HIV or HSV-2
prevalence• a significant reduction in the
number of reported current or past pregnancies
Tanzania Zimbabwe
Ross D et al, 2007; Cowan et al,2008
So far, ALL community-RCT of behavioural interventions with HIV as endpoints have shown flat results
• The intervention too weak, low adherence?
• The control group not enough different?• The outcome HIV too distal?……
The evidence dilemma
• Good quality RCT require “ tightly defined interventions” preferebly with a short impact pathway
• Combination prevention including “Social movements” advocacy, education, social mobilisation , are impractical to evaluate with RCT because less-well-defined and longer more complex impact pathway
Considerations about RCT in HIV prevention
• RCT essential for biomedical prevention tool evaluation such as microbicides
• RCT usefull for evaluation of well defined program components using intermediate outcomes in the impact pathway
• Balance cost of program implementation and learning while doing through “Convergence of evidence” versus cost of trying to prove the “unprovable”…?
Showing program impact by Convergence of Evidence
Triangulation HIV trends-Behaviour/STI-Program data
• ANC surveillance• DHS or other population based HIV prevalence
data• IBBS• Special studies: context and determinants
“documenting Social tranfsormations” • Attention to Baseline data
Criteria for effectiveness: “Plausible attribution’
• Time , place , person• Context and program factors
• Causality considerations: Bradford Hill criteria
• Modelling to simulate control groups and predict impact
Development of the 100% condom program and key strategic information in Thailand
1984 1986 1988 1990 1992 1994 1996 1998 1999 2000
The first case detected
Effective Drug for STI
Pilot project: the 100% condom from 1 to 3 to 7 provinces
All provinces implemented the 100% condom program since 1992 - Structural/policy intervention -STI and outreach -Condom promotion -Mass media
Routine STD case report and mapping, enumeration of sex establishments and sex workers Routine case report
Small scale HIV sentinel surveillance in selected provinceS
National HIV sentinel surveillance Surveillance
BSS in BKK 1993-1996
Provincial BSS since 1995 and special surveys Behavioral and outcome monitoring
The national survey of partner relations, 1990
The national survey on effectiveness of AIDS media and behavior, 1993
The national evaluation of the 100% condom promotion program, 1997
National cross-sectional surveys
Young men cohort study in the north 1991-1993
FSW cohort studies in the north 1989-1994 in the selected provinces in the north
IDU cohort study1989-1991 in BKK
IDU cohort study 1995-1996 in BKK and Chiang Mai
Cohort studies to monitor incidence
IMPACT OF SEX WORKER PROGRAMS in Benin
MODELLING OF HIV PREVALENCE in SW and General population [INTERVENTIONS OF PROJETS SIDA-1, SIDA-2, AND SIDA-3.]
IMPACT OF SEX WORKER PROGRAMS in Benin
MODELLING OF HIV PREVALENCE in SW and General population [INTERVENTIONS OF PROJETS SIDA-1, SIDA-2, AND SIDA-3.]
HIV among FSWsAssuming migration of FSWs
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1980 1985 1990 1995 2000 2005 2010 2015
Time (year)
HIV
pre
va
len
ce
Observed
No intervention
With Intervention
1st condom use increase
2nd condom use increase
Migration of FSWs
A
HIV among female general populationAssuming migration of FSWs
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
1980 1985 1990 1995 2000 2005 2010 2015
Time (year)
HIV
pre
va
len
ce
Observed
No intervention
With Intervention
B
C
Provided by M. Alary ICASA Report on West Africa, 2009
Combination prevention needs Combination evaluation
The use of a diverse range of data (mixed methods of quantitative and qualitative) and information sources , will likely provide more illuminating, relevant and sensitive evidence of effects than a single “definitive” study
Some conclusions
• Need for better Incidence measurement tools• Need for Program Impact Pathways• Back to the basics: collect and use program
Monitoring data in HIV Prevention evaluation• “Convergence of data sources” and modelling
gets us a long way in Prevention evaluation • The role of C-RCT in documenting efficacy has
been limited by complex nature of combination prevention programs
Some conclusions
• Need to better document Combination Prevention successes to respond the current crisis of confidence
• The glass is half full, but can be filled more