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      Kuantim mi tu (“Count me too”): Using Multiple Methods to Estimate the Number of Female Sex Workers, Men Who Have Sex With Men, and Transgender Women in Papua New Guinea in 2016 and 2017


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          Female sex workers (FSW), men who have sex with men (MSM), and transgender women (TGW) are at high risk of acquiring HIV in many settings, such as Papua New Guinea (PNG). An understanding of the approximate size of these populations can inform resource allocation for HIV services for FSW, MSM, and TGW.


          An objective of this multi-site survey was to conduct updated population size estimations (PSE) of FSW and MSM/TGW.


          Respondent-driven sampling (RDS) biobehavioral surveys of FSW and MSM/TGW were conducted in 3 major cities—(1) Port Moresby, (2) Lae, and (3) Mount Hagen—between June 2016 and December 2017. Eligibility criteria for FSW included: (1) ≥12 years of age, (2) born female, (3) could speak English or Tok Pisin (PNG Pidgin), and (4) had sold or exchanged sex with a man in the past six months. Eligibility for MSM/TGW included: (1) ≥12 years of age, (2) born male, (3) could speak English, or Tok Pisin, and (4) had engaged in oral or anal sex with another person born male in the past six months. PSE methods included unique object multiplier, service multiplier, and successive sampling-population size estimation (SS-PSE) using imputed visibility. Weighted data analyses were conducted using RDS-Analyst and Microsoft Excel.


          Sample sizes for FSW and MSM/TGW in Port Moresby, Lae, and Mount Hagen included: (1) 673 and 400, (2) 709 and 352, and (3) 709 and 111 respectively. Keychains were used for the unique object multiplier method and were distributed 1 week before the start of each RDS survey. HIV service testing data were only available in Port Moresby and Mount Hagen and SS-PSE estimates were calculated for all cities. Due to limited service provider data and uncertain prior size estimation knowledge, unique object multiplier weighted estimations were chosen for estimates. In Port Moresby, we estimate that there are 16,053 (95% CI 8232-23,874) FSW and 7487 (95% CI 3975-11,000) MSM/TGW, approximately 9.5% and 3.8% of the female and male populations respectively. In Lae, we estimate that there are 6105 (95% CI 4459-7752) FSW and 4669 (95% CI 3068-6271) MSM/TGW, approximately 14.4% and 10.1% of the female and male populations respectively. In Mount Hagen, we estimate that there are 2646 (95% CI 1655-3638) FSW and 1095 (95% CI 913-1151) MSM/TGW using service multiplier and successive sampling, respectively. This is approximately 17.1% and 6.3% of the female and male populations respectively.


          As the HIV epidemic in PNG rapidly evolves among key populations, PSE should be repeated to produce current estimates for timely comparison and future trend analysis.

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          Most cited references15

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          Audio computer assisted self interview and face to face interview modes in assessing response bias among STD clinic patients.

          Audio computer assisted self interview (ACASI) may minimise social desirability bias in the ascertainment of sensitive behaviours. The aim of this study was to describe the difference in reporting risk behaviour in ACASI compared to a face to face interview (FFI) among public sexually transmitted diseases (STD) clinic attendees. Randomly selected patients attending a public STD clinic in Baltimore, Maryland, sequentially took an ACASI formatted risk behaviour assessment followed by an FFI conducted by a single clinician, with both interview modalities surveying sexual and drug use behaviours. Binary responses were compared using the sign test, and categorical responses were compared using the Wilcoxon signed rank test to account for repeated measures. 671 (52% men, mean age 30 years, 95% African American) of 795 clinic attendees screened consented to participate. Subjects affirmed sensitive sexual behaviours such as same sex contact (p = 0.012), receptive rectal sexual exposure (p < 0.001), orogenital contact (p < 0.001), and a greater number of sex partners in the past month (p < 0.001) more frequently with ACASI than with an FFI. However, there were no differences in participant responses to questions on use of illicit drugs or needle sharing. Among STD clinic patients, reporting of sensitive sexual risk behaviours to clinicians was much more susceptible to social desirability bias than was reporting of illegal drug use behaviours. In STD clinics where screening of sexual risk is an essential component of STD prevention, the use of ACASI may be a more reliable assessment method than traditional FFI.
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            Social desirability bias in sexual behavior reporting: evidence from an interview mode experiment in rural Malawi.

            Social desirability bias is problematic in studies that rely on self-reported sexual behavior data. Where gender norms create different expectations about socially acceptable behavior, males and females face distinct pressures in reporting certain outcomes, which can distort assessments of risk for HIV and STIs. In 2009, relationship and sexual behavior data were collected from 1,750 never-married males and females aged 16-18 via audio computer-assisted self-interviewing (audio-CASI) during the third round of the Malawi Schooling and Adolescent Study. A comparison group of 311 youth completed an identical questionnaire in face-to-face interviews. To assess whether interview mode may have influenced participants' reporting of sensitive behavior, reports of sexual experience in the two groups were compared. Multiple logistic regression analysis was used to identify associations between interview mode and reports of these behaviors, by gender. In adjusted regression models, males were less likely to report ever having had a girlfriend in audio-CASI than in face-to-face interviews (odds ratio, 0.4), but they were more likely to report having had sex with a relative or teacher (3.5). For females, reports of ever having had a boyfriend or having had sex did not differ between modes. A small proportion of females reported ever having had sex with a relative or teacher in audio-CASI, while none did so in face-to-face interviews. The method used for collecting relationship and sexual behavior data may influence the reported prevalence of some key behaviors, particularly among males. Further research is needed to improve methods of collecting sensitive data.
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              Incorporating the service multiplier method in respondent-driven sampling surveys to estimate the size of hidden and hard-to-reach populations: case studies from around the world.

              Estimating the sizes of populations at highest risk for HIV is essential for developing and monitoring effective HIV prevention and treatment programs. We provide several country examples of how service multiplier methods have been used in respondent-driven sampling surveys and provide guidance on how to maximize this method's use. Population size estimates were conducted in 4 countries (Mauritius- intravenous drug users [IDU] and female sex workers [FSW]; Papua New Guinea-FSW and men who have sex with men [MSM]; Thailand-IDU; United States-IDU) using adjusted proportions of population members reporting attending a service, project or study listed in a respondent-driven sampling survey, and the estimated total number of population members who visited one of the listed services, projects, or studies collected from the providers. The median population size estimates were 8866 for IDU and 667 for FSW in Mauritius. Median point estimates for FSW were 4190 in Port Moresby and 8712 in Goroka, Papua New Guinea, and 2,126 for MSM in Port Moresby and 4200 for IDU in Bangkok, Thailand. Median estimates for IDU were 1050 in Chiang Mai, Thailand, and 15,789 in 2005 and 15,554 in 2009 in San Francisco. Our estimates for almost all groups in each country fall within the range of other regional and national estimates, indicating that the service multiplier method, assuming all assumptions are met, can produce informative estimates. We suggest using multiple multipliers whenever possible, garnering program data from the widest possible range of services, projects, and studies. A median of several estimates is likely more robust to potential biases than a single estimate.

                Author and article information

                JMIR Public Health Surveill
                JMIR Public Health Surveill
                JMIR Public Health and Surveillance
                JMIR Publications (Toronto, Canada )
                Jan-Mar 2019
                21 March 2019
                : 5
                : 1
                [1 ] US Centers for Disease Control and Prevention Atlanta, GA United States
                [2 ] Kirby Institute UNSW Sydney Australia
                [3 ] Papua New Guinea Institute of Medical Research Goroka Papua New Guinea
                [4 ] Papua New Guinea National Department of Health Port Moresby Papua New Guinea
                Author notes
                Corresponding Author: Damian Weikum damian.weikum@ 123456gmail.com
                ©Damian Weikum, Angela Kelly-Hanku, Parker Hou, Martha Kupul, Angelyne Amos-Kuma, Steven G Badman, Nick Dala, Kelsey C Coy, John M Kaldor, Andrew J Vallely, Avi J Hakim. Originally published in JMIR Public Health and Surveillance (http://publichealth.jmir.org), 21.03.2019.

                This is an open-access article distributed under the terms of the Creative Commons Attribution License ( https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work, first published in JMIR Public Health and Surveillance, is properly cited. The complete bibliographic information, a link to the original publication on http://publichealth.jmir.org.as well as this copyright and license information must be included.

                Original Paper
                Original Paper

                papua new guinea,population size estimation,female sex workers,men who have sex with men,transgender women,key populations,respondent-driven sampling,unique object multiplier,service multiplier,successive sampling


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