Introduction to Behavioral Surveillance Surveys
FHI's Behavioral Surveillance Surveys (BSS) provide valuable data about HIV/AIDS-related knowledge, attitudes, and behaviors. The BSS methodology is a monitoring and evaluation tool designed to track trends in HIV/AIDS-related knowledge, attitudes, and behaviors in subpopulations at particular risk of HIV infection, such as female sex workers, injection drug users, migrant men, and youth. Based on classic HIV and sexually transmitted disease (STD) serologic surveillance methods, BSS consist of repeated cross-sectional surveys conducted systematically to monitor changes in HIV/STD risk behaviors. A key benefit of the methodology is its standardized approach to questionnaire development, sampling frame construction, and survey implementation and analysis. BSS findings serve many purposes: they yield evidence of project impact, provide indicators of project success and highlight persistent problem areas, identify appropriate intervention priority populations, identify specific behaviors in need of change, function as a policy and advocacy tool, and supply comparative data concerning behavioral risks.
BSS have been conducted in more than 20 countries -- primarily in Africa and Asia -- since 1992, and their use in Latin America and the Caribbean is growing. Since 1999 they have been used in cross-border sites in Asia and Africa, where they are proving beneficial for understanding the pandemic from a regional instead of a purely country-specific perspective. In several countries multiple rounds of BSS have been implemented already, with the trend data used to formulate new programs and to adapt existing ones.
Introduction to the Bangkok BSS
Thailand was one of the first countries to implement BSS in the context of an HIV prevention program. The government of Thailand has been proactive in its attempt to arrest and control the epidemic through behavioral and sentinel surveillance and a variety of prevention initiatives. The National AIDS Committee of the Thai Ministry of Health is responsible for developing and implementing programs to educate people about HIV/AIDS and sexually transmitted disease and to prevent the spread of these diseases through condom promotion and STD treatment.
Seroprevalence data have been available annually or semiannually since 1985 and have provided critical information concerning the spread of the epidemic. These data indicate that two independent epidemics evolved among injecting drug users and female sex workers (FSWs), with subsequent waves spreading among clients of female sex workers and the wives and other sex partners of these clients. Targeted interventions among these populations, such as requiring 100 percent condom use among FSW and their clients, have led to a gradual decrease in HIV incidence and prevalence. Regular behavioral surveillance, combined with ongoing serosurveillance, has allowed the tracking of trends and contributed to the development and adaptation of the interventions responsible for reductions in HIV.
The Bangkok Behavioral Surveillance Surveys (BSS) were carried out between 1993 and 1996. The results of a national BSS, which has been carried out since 1995, have been reported elsewhere (Mills et al. AIDS 1997, 11 (suppl 1): S43-S51). This report summarizes findings from the five waves of the Bangkok BSS, conducted twice a year from 1993 through 1996.
Study Design and Methodology
Study population
The Bangkok BSS included subpopulations from eight socioeconomic groups. Direct and indirect female sex workers were selected because of the high HIV prevalence among them and the presumed importance of their risk behaviors in the spread of the epidemic. Male and female vocational students, and male and female factory workers, were chosen because they represented young, potentially at-risk populations from a variety of socioeconomic and occupational groups. Male STD clinic attendees and female antenatal clinic attendees were also surveyed. Data from these groups are not presented here, however, because their inclusion in BSS is no longer recommended due to the potential bias in risk behavior in these groups. (ANC clients have necessarily practiced unprotected sexual intercourse in order to become pregnant, just as STD clinic attendees have practiced unprotected -- and presumably high-risk -- sex leading to sexually transmitted infection).
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Bangkok BSS Subpopulation Definitions |
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Direct Female Sex Workers (DSWs)
Sex workers who sell sex directly and have received money for sex services in the past year
Indirect female sex workers (ISWs)
Sex workers who usually provide a service in addition to sex that is negotiated at a separate price and who have received money for sex services in the past year
Male factory workers (MFWs)
Employed at a factory with fewer than 500 employees and 15-29 years of age
Female factory workers (FFWs)
Employed at a factory with fewer than 500 employees and 15-29 years of age
Male vocational students (MVSs)
Enrolled in a post-secondary educational institution that provides vocational training and 15-18 years of age
Female vocational students (FVSs)
Enrolled in a post-secondary educational institution that provides vocational training and 15-18 years of age |
Five data sets were collected in two phases. The initial phase was conducted in six Bangkok districts and included two periods of data collection: (1) February - December 1993 and (2) September 1993 - August 1994. The second phase, conducted from October 1994 through July 1996, was a full implementation phase in which three sets of data were collected in 34 of Bangkok's 38 districts: (3) October 1994 - March 1995 (4) June - November 1995 (5) February - July 1996.
Sample size
The number of respondents for each group was determined based on the estimated number of subjects needed to detect a 10 percent change in key risk behaviors (such as percentage using condoms with non-regular sex partners) across time. During the full implementation phase, sample sizes were considerably increased for female factory workers and female vocational students in order to obtain larger numbers of subjects reporting risk behaviors. Table 1 shows sample sizes of subpopulations included in the five survey waves.
Table 1. Sample sizes for groups surveyed by data collection wave
| |
Sample Size |
| Subpopulation |
Wave 1 |
Wave 2 |
Wave 3 |
Wave 4 |
Wave 5 |
Feb - Dec 1993
6 districts |
Sept 1993 - Aug 1994
6 districts |
Oct 1994 - Mar 1995
34 districts |
Jun - Nov 1995
34 districts |
Feb - July 1996
34 districts |
| Direct female sex workers |
283 |
212 |
242 |
191 |
283 |
| Indirect female sex workers |
279 |
274 |
155 |
371 |
391 |
| Male factory workers |
299 |
300 |
296 |
297 |
293 |
| Female factory workers |
158 |
161 |
1256 |
1249 |
1259 |
| Male vocational students |
300 |
300 |
400 |
399 |
400 |
| Female vocational students |
270 |
280 |
1165 |
1141 |
1163 |
Sample design
Site lists provided by the Bangkok Metropolitan Administration and the Community Mobilization Project of the AIDS Prevention and Control Project (AIDSCAP) were used to construct the sampling frames for the subpopulations included in the Bangkok BSS. Within each district, samples were taken from direct and indirect commercial sex establishments, factories with fewer than 500 employees, and vocational schools. The same sites were used in waves 1 and 2, based on a random selection performed for wave 1. New sites were randomly selected from 34 districts for wave 3, and those same sites were used for waves 4 and 5. Sites included in waves 1 and 2 were only included in waves 3 through 5 if they were randomly selected. Site managers, owners and teachers at randomly selected sites were asked to make a random selection of a fixed number of individuals to participate in the survey.
A structured questionnaire was used to collect data. The questionnaire was administered by trained interviewers of the same sex as the respondents, except for the sexual behavior component of the questionnaire administered to female factory workers and female students, which was self-administered.
Results
Socio-demographic characteristics
Age
Among the female subpopulations, direct sex workers (DSWs) had the highest mean age (27). The female and male vocational students (FVSs) had the lowest mean age (18 respectively) of all subpopulations.
Literacy
Among all subpopulations, direct sex workers had the least education, with 61 percent reporting completing secondary school. Among the male and female factory workers, almost all had completed secondary school.
Marital status
One hundred percent of the "non-sex worker" female subpopulations reported being single. The majority of the direct sex workers were single, separated, divorced or widowed.
Table 2. Sample characteristics of each subpopulation for all data sets
| |
DSW |
ISW |
MFW |
MVS |
FFW |
FVS |
| Mean age (yrs) |
27 |
24 |
22 |
18 |
21 |
18 |
| no schooling (percent) |
12 |
5 |
0 |
0 |
0 |
0 |
| primary school (percent) |
27 |
17 |
4 |
0 |
4 |
0 |
| secondary school (percent) |
61 |
78 |
96 |
100 |
96 |
100 |
| Married (percent) |
19 |
30 |
26 |
1 |
0 |
0 |
| Single (percent) |
39 |
27 |
73 |
99 |
100 |
100 |
| Separated/divorced/widowed (percent) |
42 |
43 |
1 |
0 |
0 |
0 |
Trends in BSS Behavioral Indicator
Reported patronage of commercial sex by men in the past year
The data indicate that reported patronage of commercial sex significantly declined between 1993 and 1996 for all male subpopulations (figure 1). Vocational students reported the greatest decline (approximately 50 percent). Male factory workers also decreased patronage of commercial sex, from 22 percent to 14 percent.
Figure 1. Men reporting sex with a FSW in past year
Currently has a non-paying sex partner
Among sex workers, indirect sex workers were more likely to have a non-paying sex partner (55 percent) than direct sex workers (38 percent).
Non-regular sex partners among men in the past year
In the Bangkok BSS, non-regular sex partners were defined as a sex partner other than a wife for married men and a sex partner other than a girlfriend or fiancée for single men. Only five percent or fewer of the male vocational students or male factory workers reported having had a non-regular, non-commercial sex partner in the past 12 months.
Most recent sex and consistent condom use in the past year by sex workers
No significant trends were shown in condom use during most recent sex with a paying client for either direct or indirect sex workers, although condom use at last sex was high for both subpopulations. Significant trends were apparent, however, in consistent condom use with clients for both types of sex workers. Indirect sex workers had the greatest increase in consistent condom use with clients, from 56 percent in 1993 to 89 percent in 1996 (figure 2). Consistent use among direct sex workers increased from 87 percent to 97 percent during the same period of time. At the same time, consistent condom use was much less common with non-paying sex partners than with clients among both types of sex workers, and the data showed no significant changes.
Figure 2. FSW consistent condom use in past year
Sexual intercourse in the past year among women
All the female vocational students and factory workers surveyed reported being single. In 1995, female factory workers showed a downward trend in the percentage reporting sexual intercourse during the past year. Only three percent had had sexual intercourse in 1995, down from 6 percent in 1993. Sexual activity among female vocational students decreased from a high of 7 percent in 1994-1995 to 3 percent in 1996. Among sexually active women (other than sex workers), the numbers of women having sex with non-regular partners were too low for researchers to draw significant conclusions regarding trends in sexual risk behavior.
Summary of Findings
- The most remarkable changes over these five survey rounds were in the commercial sex industry, with all male subpopulations reporting decreased patronage of sex workers.
- The percentage of men having non-commercial, non-regular sex partnerships also decreased, suggesting that non-regular partnerships were not replacing commercial sex partnerships.
- Most subpopulations surveyed reported high rates of condom use, with the exception of condom use between sex workers and their non-paying partners. Condom use between these partners remains low, with no signs of changing.
- All non-sex-worker female subpopulations reported low levels of sexual intercourse.
Technical Guidelines
For more information, see the following technical guidelines:
UNAIDS and Family Health International, May 1998. Meeting the Behavioural Data Collection Needs of National HIV/AIDS and STD Programmes.
Discusses behavioral data collection needs by different epidemic state. Reflects recent thinking about the best use of resources in behavioral data collection in the context of second generation surveillance.
Family Health International, June 2000. Behavioral Surveillance Surveys (BSS): Guidelines for Repeated Behavioral Surveys in Populations at Risk for HIV.
Provides how-to information that includes identifying priority subpopulations, developing sampling frameworks and approaches, and suggesting analysis and dissemination strategies. Also includes sample questionnaires.
UNAIDS and WHO, 2000. Guidelines for Second Generation HIV Surveillance.
Provides an overview of the principal issues that need to be considered in strengthening surveillance systems and increasing their utility. Suggests priority approaches for the various epidemic states.
Acknowledgments
The Bangkok BSS were executed and administered by:
Office for Population and Technical Assistance (OPTA)
With technical assistance from:
Family Health International
Funded by:
The United States Agency for International Development (USAID)
This executive summary is based on the following report:
Mills S, Benjarattanaporn P, Bennett A, Pattaling RN, Trongsawad P, Gregorich SE, Hearst N, Mandel JS. HIV Risk Behavioral Surveillance in Bangkok, Thailand: Sexual Behavior Trends among Eight Population Groups. AIDS 1997, 11 (suppl1): S43-S51.
