Assessing the Impact of a HIV Prevention Program
Among Transgender People in Thailand
Using Coarsened Exact Matching
Duangta Pawa
Gary Mundy
Yaowalak Jittakoat
Sindh Ratchasi
Evaluation 2013
October 16-19, 2013
PAGE 2
Introduction
 HIV prevalence among
transgender women is
10% in Thailand*
 Transgender women face
discrimination and stigma
within their families or
working life, with a
significant of this
population being involved
in commercial sex work
*Integrated Biological and Behavioral Surveillance among Men who have Sex with Men (MSM) in Thailand, 2011
PAGE 3
Sisters Program
The purpose of the program is to promote safer sex among
transgender women through peer education and drop in center
activities in eastern Thailand
PAGE 4
Sisters Program
Intervention Area: Eastern Thailand
Pattaya, Sattahip and Sriracha
in Chonburi Province, Thailand
Sisters Intervention:
 Drop-in center
Sriracha
– Counseling
– Social services
– On-site HIV testing
 Peer-led interpersonal communication
 Home visit
Pattaya
Sattahip
Map of Chonburi Province, Thailand
PAGE 5
Research Objectives
 To be a baseline of behaviors;
•
•
•
Condom use at last sex and consistent condom use
with each partner type
Consistent water-based lubricant use along with
condom and
HIV test
 Assess the effectiveness of Sister’s model for
reducing HIV risks among the transgender women in
Thailand
PAGE 6
Methods
Study Design:
Date of Data Collection:
Sampling:
Cross Sectional Study
December 2011
Time-location Sampling
Data Collection Method:
Study Questionnaire:
Interview
Scaled items presented on
6-point Likert scale,
yes-no questions, and
multiple choice questions
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Measurement
 Outcomes
– Condom use at last sex
– Consistent condom and water-based lubricant use in the
past three months
– Receipt of an HIV test in the past six months.
 Program participation
– Receipt of any Sisters services in the past 12 months
– Attendance at the Sisters drop-in center (DIC)
– Interaction with a Sisters outreach worker
PAGE 8
Analysis Approach
 To improve causal inferences of estimates of
program effectiveness, we used statistical matching
as a quasi-experimental method to enable clear
designation of a counterfactual
Coarsened Exact Matching (CEM)
• A statistical technique used in observational studies to create
treated cases (program participants) and control cases (nonparticipants), matched on observed factors that influenced
selection into treatment
PAGE 9
Matching Technique
Matching Variables
•
•
•
•
Duration of residence in Pattaya: < 1 year, > 1 years
Monthly income: <20,000THB/month, >20,000THB/month
Occupation: work in entertainment venue, work as a freelance sex worker
Number of transgender friends
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RESULTS
PAGE 11
Condom Use
85%
73%
62%
62%
55%
36%
Consistent condom Consistent condom Consistent condom
Consistent
Consistent condom
Consistent
use in the past 3 and water-based use in the past 3
condom/wateruse in the past 3
condom/watermonths
lubricant use in
months
based lubricant use
months
based lubricant use
past 3 months
in the past 3
in the past 3
months
months
Commercial partners
Casual partners
Regular partners
PAGE 12
HIV Test
Sisters Participation
72%
64%
55%
40%
17%
HIV testing
Received any Sisters service Visited Sisters drop-in center Received Sisters outreach
Program participation in the past 12 months
Received Sisters home visit
PAGE 13
Interaction with Sisters and Condom Use
Matching Variables
• Duration of residence in Pattaya
• Monthly income
• Occupation
• Number of transgender friends
Condom Use at Last Sex with Any Partner
Indicator
Received any Sisters services
Interaction with a Sisters outreach
worker
CI 95%
Odds
ratio
Lower
Upper
3.75
1.41
9.97
0.121
3.10
1.15
8.32
0.025
P-value
PAGE 14
Interaction with Sisters and Condom Use
Matching Variables
• Duration of residence in Pattaya
• Monthly income
• Occupation
• Number of transgender friends
Consistent Condom/Water-Based Lubricant Use in Past 3 Months
Indicator
Received any Sisters services
Interaction with a Sisters outreach
worker
CI 95%
Odds
ratio
Lower
Upper
2.37
1.28
4.41
0.006
2.72
1.50
4.92
0.001
P-value
PAGE 15
Interaction with Sisters and HIV testing
Matching Variables
• Duration of residence in Pattaya
• Monthly income
• Occupation
• Number of transgender friends
Received an HIV Test in the Past 6 Months
Indicator
Received any Sisters services
Attendance at the Sisters drop-in
center
CI 95%
Odds
ratio
Lower
Upper
2.45
1.36
4.39
0.003
2.80
1.62
4.83
0.000
P-value
PAGE 16
Limitation
 Recall bias in the outcomes
– Consistent condom and lubricant use
– Program participation
 Small sample size for transgender women that have
casual and regular partner
PAGE 17
Discussion and Conclusion
 An HIV prevention program targeted to transgender
women can address HIV-related risks
 The program influenced condom use at last sex and
consistent condom use along with water-based
lubricant in past 3 months
 Receipt of an HIV test was strongly related to
participation in Sisters services
 CEM could be used to assess the effectiveness of
the program when an experimental design was not
an option with on-going program implementation and
with a hard-to-reach population
PAGE 18
Questions?
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