Review of sampling hard-to-reach and hidden populations for HIV surveillance

Adequate surveillance of hard-to-reach and 'hidden' subpopulations is crucial to containing the HIV epidemic in low prevalence settings and in slowing the rate of transmission in high prevalence settings. For a variety of reasons, however, conventional facility and survey-based surveillance data collection strategies are ineffective for a number of key subpopulations, particularly those whose behaviors are illegal or illicit. This paper critically reviews alternative sampling strategies for undertaking behavioral or biological surveillance surveys of such groups. Non-probability sampling approaches such as facility-based sentinel surveillance and snowball sampling are the simplest to carry out, but are subject to a high risk of sampling/selection bias. Most of the probability sampling methods considered are limited in that they are adequate only under certain circumstances and for some groups. One relatively new method, respondent-driven sampling, an adaptation of chain-referral sampling, appears to be the most promising for general applications. However, as its applicability to HIV surveillance in resource-poor settings has yet to be established, further field trials are needed before a firm conclusion can be reached.

Preventing HIV infection through peer education and condom promotion among truck drivers and their sexual partners in Tanzania, 1990-1993

HIV prevention through peer education and condom promotion among truck drivers and their sexual partners is described. Trends during an initial 18-month intensive phase, followed by a 24-month maintenance phase, were monitored with surveys. Trends for self-reported condom use were: increase among men (56 to 74%) during the first phase with a decrease (72%) during the maintenance phase. Respective figures for women were 51%, 91% and 70%. Multivariate analyses revealed that men most likely to report using condoms were unmarried, had children, were more educated, had previously reported a genital ulcer, and perceived themselves at risk for HIV infection (OR = 1.95-3.47). Women tending to use condoms were unmarried, aware of the limitations of condoms, not in denial as to the existence of HIV, harboured inaccurate information about HIV transmission and were afraid (OR = 1.35-2.52). Both sets of results suggest that the most sexually experienced men and women who did not have a permanent stable relationship and who perceived themselves at risk, were most likely to use a condom. Peer education was an effective tool for increasing knowledge and encouraging appropriate behaviour change. It was most effective as an intensive high-input intervention and sustainable with the relatively stable population of truck drivers.

Intravenous drug use among street-based sex workers: a high-risk behavior for HIV transmission

BACKGROUND

HIV prevalence among sex workers in Ho Chi Minh City has increased rapidly, from 6.5% in 1999 to 18.1% in 2000. This study examined whether injecting drug use among street-based sex workers (SSWs) in Ho Chi Minh City is a high-risk factor for HIV infection.

GOAL

The goal of this study was to determine the correlates and prevalence of intravenous drug users among SSWs in Ho Chi Minh City.

STUDY DESIGN

A cross-sectional study was conducted among SSWs in Ho Chi Minh City during December 2000. The SSWs were interviewed and tested for HIV-1.

RESULTS

HIV-1 seroprevalence was 16.3%. Regression analysis indicated that injecting drugs and being younger than 25 years of age were independently associated with HIV seropositivity.

CONCLUSION

Young SSWs who inject drugs are at the greatest risk of contracting HIV and acting as a bridge for HIV to the sexually active population.

Surveillance and modelling of HIV, STI, and risk behaviours in concentrated HIV epidemics

BACKGROUND

HIV epidemics in most countries are highly concentrated among population subgroups such as female sex workers, injecting drug users, men who have sex with men, mobile populations, and their sexual partners. The perception that they are important only when they cause epidemic expansion to general populations has obscured a critical lack of coverage of preventive interventions in these groups, as well as appropriate methods for monitoring epidemic and behavioural risk trends. The difficulties in accessing such groups have likewise often cast doubt on the representativeness of observed disease and behavioural risk estimates and their validity and reliability, particularly those related to sampling and the measurement of risk behaviours.

OBJECTIVES

To review methodological obstacles in conducting surveillance with population subgroups in concentrated HIV epidemics, elaborate on recent advancements that partially overcome these obstacles, and illustrate the importance of modelling integrated HIV, STI, and behavioural surveillance data.

METHODS

Review of published HIV, STI, and behavioural surveillance data, research on epidemic dynamics, and case studies from selected countries.

CONCLUSIONS

The population subgroups that merit regular and systematic surveillance in concentrated epidemics are best determined through extensive assessment and careful definition. Adherence to recently refined chain referral and time location sampling methods can help to ensure more representative samples. Finally, because of the inherent limitations of cross sectional surveys in understanding associations between complex sexual behaviours and HIV and STI transmission, mathematical models using multiple year data offer opportunities for integrated analysis of behavioural change and HIV/STI trends.

HIV, STIs, and sexual behaviors among men who have sex with men in Phnom Penh, Cambodia

A probability sample of 206 men who have sex with men from 16 sites in Phnom Penh were surveyed about sexual behaviors and tested for HIV and sexually transmitted infections (STIs). HIV and syphilis prevalence was 14.4% and 5.5%, respectively. Out of the total sample, 81% reported anal sex with any male partners in the past 6 months, and 61.2% reported having had vaginal sex. In the past 6 months, 82.8% of the sample reported having male partners who paid them to have sex. Self-reported sexual orientation did not match well with self-reported sexual behavior. Significant risk factors for HIV infection were anal sex with multiple partners, unprotected vaginal sex with commercial female partners in the past month, and any STI. Complex sexual networks indicate that men who have sex with men act as a bridge between higher and lower HIV prevalence populations. Better prevention efforts structured around behaviors rather than sexual identities are needed.

Measuring the impact of needle exchange programs among injecting drug users through the National Behavioural Surveillance in Bangladesh

Bangladesh is a low HIV prevalence country, with buprenorphine injectors having the highest prevalence of HIV at 2.5% as of 1999. Using National HIV Behavioral Surveillance data, the impact of a needle exchange program (NEP) on sharing behavior among injecting drug users in two cities was measured. Results showed positive changes that varied with the different settings. Those who reported utilizing the NEP were compared with those who did not. Differences in Dhaka were significant for the average proportion of needles shared but not for the proportion of men who ever shared in the last week. In Rajshahi, where professional injectors were the norm, the impact of an NEP was greater and affected both the proportion of needles shared as well as the proportion of men never sharing. Behavioral surveillance methods have the potential to measure intervention impact through comparative analysis in certain settings.

Validation of a method to estimate age-specific human immunodeficiency virus (HIV) incidence rates in developing countries using population-based seroprevalence data

The authors have conducted an analysis to validate a computer model that uses age-specific human immunodeficiency virus (HIV) prevalence data to estimate age-specific HIV incidence rates. Data for the analysis are from a cohort study of volunteer male workers in Bujumbura, the capital city of Burundi. Testing for HIV prevalence was conducted at baseline, and HIV-negative subjects were retested annually from 1990 to 1993 to determine rates of seroconversion. Input parameters required for the model include age-specific HIV prevalence and estimates of age-specific mortality rates for HIV-negative and HIV-positive subjects. Incidence rate estimates from the model were 2.0, 2.7, 1.0, 1.5, and 1.8 per 100 person-years for age groups 20-24, 25-29, 30-34, 35-39, and 40-44 years, respectively. Corresponding observed incidence rates for the same age groups were 1.6, 1.8, 2.2, 2.3, and 1.5 per 100 person-years, respectively. Most observed incidence rates fell within the 95% confidence limits of the model estimates. Expected numbers of cases within age intervals did not differ significantly from observed number of cases. The authors conclude that the model proved to be successful in approximating observed incidence rates and that it is a useful tool, particularly in countries where prevalence data are available and where HIV prevalence has stabilized, which is when the underlying assumptions in the model are best met. The model provides crucial information about incidence rates that might not be evident from prevalence data alone.

High rates of reinfection and incidence of bacterial sexually transmitted infections in a cohort of female sex workers from two Indian cities: need for different STI control strategies?

Background

Female sex workers (FSWs) in India are provided a standardised package of clinical interventions for management of sexually transmitted infections (STIs). A study was conducted among FSWs at known high STI prevalence sites to determine the effectiveness of the service package.

Methods

A cohort of FSW clinic attendees in two cities, Hyderabad and Mumbai, were enrolled and followed up from October 2008 to November 2009. At each visit, behavioural and clinical data were obtained and vaginal swabs collected for laboratory testing of cervical infections (gonorrhoea and chlamydia).

Results

417 participants were enrolled, of whom 360 attended at least a follow-up visit. Prevalence of cervical infections did not change between the baseline and final visits (27.7% and 21.3% respectively, p=0.08) in spite of presumptive treatment at baseline and syndromic management at all visits. The proportion of asymptomatic cervical infections increased from 36% at baseline to 77% at the final visit. Incidence rate of cervical infections was high (85.6/100 person years) and associated with a prevalent cervical infection at baseline (HR=2.7, p<0.001) and inconsistent condom use with non-commercial partners (HR=2.5, p=0.014).

Conclusions

High rates of STIs persisted despite the interventions due to poor condom use, minimal partner treatment, and high prevalence and incidence of STIs with a large proportion of asymptomatic infections. High-prevalence FSW sites in India need to design more effective partner treatment strategies and consider increasing the frequency of presumptive treatment as a temporary measure for quickly reducing STI prevalence, with renewed emphasis on consistent condom use with all partners.

Assessment of non-marital sexual behaviours of men in Bangladesh: a methodological experiment using a modified confidential ballot-box method

This study assessed the effectiveness of a modified ballot-box method (MBBM) in eliciting non-marital sexual behaviours compared with face-to-face interview (FTFI). A cross-sectional survey collected data from men aged 18–49 years in Bangladesh using a multistage cluster sampling method. In total, 3499 and 3623 respondents were interviewed by MBBM and FTFI, respectively. In the MBBM, pre-recorded questions were administered using a portable audio-cassette player with two pairs of headphones used concurrently by the respondent and the interviewer. Overall, 18% of the respondents had non-marital sexual exposure in the past year. The MBBM elicited higher responses of non-marital sex (adjusted odds ratio (aOR) 1.3, 95% confidence interval [CI]: 1.1, 1.5) compared with FTFI. The interview methods did not, however, revealed significant differences in response to condom-use rates and the number of non-marital sexual partners. The MBBM is more effective than the FTFI method in eliciting higher responses rates of non-marital sexual contacts and may be recommended for reliable estimates of sexual behaviours.

980Quantifying inadvertent data-duplication- findings from validation of antenatal-registration and HIV-testing data-sets from an Indian state

Background

India plans elimination of HIV-Mother-to-Child-Transmission in 2020. Targets include &gt;95% coverage of Antenatal-care (ANC) and HIV-testing. In 2015-16, while 43% of the estimated Indian pregnant-women (PW) received HIV-tests, one state reported &gt;95% testing. Indian public-health-care is a three-tiered system from primary-level sub-centres (population-5000) to tertiary-level hospitals. ANC involves multiple-visits per pregnancy at different care-levels and data are aggregated in the Health-Management-Information-System (HMIS) at all levels. We validated (public and private-sector data from this state, for duplication in ANC registration and HIV-testing using mixed methods.

Methods

In the absence of guidelines for assessing aggregate-data duplication, we used mixed-methods, including surveys among 9845 PW and providers from 240 facilities in 10/36 representative districts; in-depth-interviews; case-studies and analysis of HMIS and HIV-program data (April 2015-Mar 2017). Interviews and case-studies highlighted inadvertent duplicate data-capture. Surveys quantified levels of duplication and adjustment factors (public and private-sector) were developed.

Results

Twenty-four% PW, visited multiple facilities for ANC, while 81% providers reported all the PW coming to their facilities as new ANC registrations (irrespective of lower-tier registration); identifying a minimum duplication of 19% (24%*81%) in ANC coverage. Twenty-nine% and 28% PW from public and private-facilities reported &gt;1 HIV-test; while 75% and 36% reported visiting another public-facility where HIV test was likely to be reported again. Minimum duplication of 22% and 10% in HIV testing was noted in public and private-sectors respectively.

Conclusions

We report methods to quantify repeat HIV-testing and duplicate-reporting, due to inherent processes in ANC in public-healthcare in India. Modification of data-capture was recommended and adopted across India.

Key messages

Assessing duplication in aggregate health data is key to developing robust datasets for disease elimination

[The prevalence of HIV and risk behavior of prostitutes living in 2 populous regions of Bujumbura (Burundi)]

This study was designed to determine the prevalence of HIV infection and associated high-risk behavior in female sex workers in two areas of Bujumbura (Bwiza and Musanga), Burundi. Between June 15th and July 15th 1993, 320 female sex workers responded to an anonymous questionnaire and gave a blood sample on filter paper for detection of HIV antibodies. The mean age of the prostitutes was 24.6 (+/- 5.9) years (range 15 to 46). The HIV infection rate was 42.2% (135 of the 320). Univariate analysis showed that the proportion of HIV-infected female sex workers was higher in the Musaga area than in Bwiza (48.3% versus 34.3%; p = 0.012). The prevalence of HIV infection increased with age (24.3% for those aged between 15 and 19; 40.8% for those aged between 20 and 24 and more than 51.4% infected in the over 25 age-group; p < 0.001). The median number of sexual partners in the preceding month was 3 (range 1 to 50) and was not correlated with HIV infection (Wilcoxon's test: p = 0.516). HIV infection was highly correlated with a previous history of STDs (62.7% versus 32.7%; p < 0.001) and was also correlated with STD symptoms (87.5% versus 51.7%; p = 0.01). The only factors correlated with HIV infection in multivariate analysis were age (p = 0.008; Trend's test) and previous history of STDs (p < 0.001). Only 40.2% (127 of 316) of the female sex workers had used condoms with their clients during the preceding month. Intervention strategies to combat HIV transmission among individuals with high levels of sexual activity in Burundi should focus on the female sex workers and their clients, particularly the manual laborers, drivers, soldiers, prisoners and other men who regularly use prostitutes. The prevention of HIV infection in individuals of high-risk groups is the best strategy to reduce HIV transmission in the general population of developing countries.

Targeted intervention research studies on sexually transmitted diseases (STD): methodology, selected findings and implications for STD service delivery and communications

OBJECTIVE

To report the findings of qualitative studies designed for use in improving sexually transmitted disease (STD) programs. The studies explore illness conceptions and treatment behaviors for STD in five African countries. These targeted intervention research (TIR) studies were performed on clinic-based and community-based samples in representative communities and utilized a variety of qualitative research methods (e.g. in-depth and key informant interviews, focus group discussions).

FINDINGS

Study findings revealed that community members' explanations of symptoms, classification of illnesses, and perceptions of whether symptoms are pathological or serious influence individual health-care-seeking behaviors. Data also showed that local terms for STD are often disparaging and do not fit into biomedical designations. STD patient care-seeking frequently reflects an ordered, albeit loosely constructed, process of elimination in pursuit of symptom relief, wherein alternative treatments are tried and proven effective or abandoned.

CONCLUSIONS

The TIR studies highlight the importance of community-specific strategies aimed at increasing prompt care seeking at qualified biomedical facilities. Information from study data should lead programs to sensitize health professionals to community understanding about STD and to design services and communication programs that are meaningful and appropriate to local contexts.

HIV risk behavioral surveillance: a methodology for monitoring behavioral trends

OBJECTIVE

This article summarizes issues and recommendations for conducting HIV risk behavioral surveillance surveys (BSS) based on experiences from ten BSS projects in eight countries in Asia and Africa.

BACKGROUND

BSS consists of systematic and repeated cross-sectional surveys of HIV and sexually transmitted disease-related behaviors, with other knowledge and attitudinal variables added where appropriate. Its major purpose and utility is in detecting trends among selected vulnerable and high-risk population groups whose behavioral change can have the most impact on the epidemic. BSS is also useful for tracking trends in behaviors over time in regions exposed to HIV prevention activities, as a contributing component to the comprehensive monitoring and evaluation of interventions.

RECOMMENDATIONS

(i) implement BSS as an essential adjunct to HIV/STD epidemiological surveillance; (ii) use BSS for evaluation purposes in combination with process data and triangulate results with qualitative research; (iii) choose sentinel groups based on epidemiological considerations, evaluation and monitoring needs, representative sampling frames, and political and cultural considerations; (iv) maintain 1-year intervals between survey waves for most groups in order to provide yearly updates on behavioral trends for programmatic adjustments; (v) use internationally standardized indicators and question wording; (vi) maintain strict quality control standards to enhance data validity and reliability; and (vii) develop a clear dissemination strategy during BSS design to increase the likelihood of utilization of BSS results.

CONCLUSION

BSS represents a cost-effective way to determine whether programmatic behavioral targets and goals are being met, to identify persisting risk behaviors over time, and to indicate whether new intervention approaches are necessary.

How well do antenatal clinic (ANC) attendees represent the general population? A comparison of HIV prevalence from ANC sentinel surveillance sites with a population-based survey of women aged 15-49 in Cambodia

BACKGROUND

The purpose of this study was to evaluate whether HIV-1 prevalence among antenatal clinic (ANC) attendees in Cambodia provided a reasonable estimate of HIV-1 prevalence among all women 15-49 years. METHODS Antenatal clinic attendees in five HIV sentinel surveillance sites (five provinces) were selected by consecutive sampling (n = 1695). The population survey of females by household was carried out in the same five areas. Household females aged 15-49 years were selected using a three-stage cluster sampling design (n = 3066). Serum-based HIV ELISA testing was done for both ANC attendees and household females. The HIV prevalence for ANC attendees and household females were compared by age group and urban versus rural location.

RESULTS

The overall prevalence of HIV-1 infection among ANC attendees (1.62%, 95% CI : 1.26-1.98) was similar to the overall prevalence obtained from the general population of household females (1.24%, 95% CI : 0.92-1.55) in the same catchment areas in Cambodia. In the rural areas, the overall HIV prevalence among ANC attendees (2.18%, 95% CI : 1.59-2.77) was significantly higher than among the household females (0.86%, 95% CI : 0.49-1.23) after adjustment for age distribution and education level. In the 15-24 age group in rural areas, the HIV prevalence of ANC women was 2.71% (95% CI : 0.96-4.46) compared with 0.77% (95% CI : 0.02-1.53) in household females.

CONCLUSIONS

Although ANC data can be used to estimate trends over time, it should be realized that ANC data may overestimate the actual prevalence in the younger age group in rural areas in Cambodia.