Size Estimation of Most-at-Risk Groups of HIV/AIDS Using Network Scale-up in Tabriz, Iran

Abstract

Ab s t r a c tPurpose: To begin to manage a serious health problem like AIDS, it is crucial that we know the size of the subpopulation related to the problem. In this study we used Network scale-up method (NSUM), an indirect method of size estimation of hard-to-reach subpopulation, to estimate most-at-risk population (MARPs) of Tabriz. Methods:Having adapted a purposive sampling, we interviewed 500 people of target population. To estimate the size of social network (C), we used known population method through collecting data of 29 known sub-groups. To estimate most-at-risk populations, we applied frequency approach of NSUM. Adjustments were done to correct common errors of this method. Results:Among groups at risk due to sexual contact, the greatest frequency was related to clients of female sex workers (CFSWs) with 831 out of 100000 of men's population (95% CI: 649, 1055), then female sex workers (FSWs) with 709 out of 100000 of women's population (95% CI: 512, 930). Among groups at risk due to drug use, the biggest frequency belonged to alcoholic substance users with 1136 out of 100000 of total population (95% CI: 955, 1332). After that, it included opium users, crystal users and injecting drug users (IDUs), respectively. Conclusion:Although the estimated number of MARPs in Tabriz is less than other areas, it is necessary to perform preventive programs like harm reduction programs to reduce transmission of AIDS.

A Sample Size Formula for Network Scale-up Studies

“…Bernard et al (1991) introduced the network scale-up method (NSUM) to estimate the number of people who died in the 1985 Mexico City earthquake. NSUM has subsequently been employed to estimate the number of men who have sex with men (Ezoe et al 2012;Wang et al 2015;Sulaberidze et al 2016;Guo et al 2013), sex workers (Maghsoudi et al 2014;Jami, Baneshi, and Nasirian 2021;Jing et al 2018;Guo et al 2013), trafficked persons (Shelton 2015), infected or at-risk individuals (Killworth et al 1998b(Killworth et al , 1998aUNAIDS and World Health Organization 2010;Salganik et al 2011;Shokoohi, Baneshi, and Ali-akbar 2012;Center 2012;Guo et al 2013;JafariKhounigh et al 2014;Jing et al 2014;Teo et al 2019;Heydari et al 2019;Haghdoost et al 2015;Sajjadi et al 2018), drug users (Kadushin et al 2006;Nikfarjam et al 2016;Sheikhzadeh et al 2016;Guo et al 2013;Maghsoudi et al 2014), prisoners (Zheng, Salganik, and Gelman 2006), victims of disasters (Bernard et al 2001), abortions (Rastegari et al 2014), choking incidents in children (Snidero et al 2007), religious individuals (Yang and Yang 2017), and people in one's personal network (McCormick et al 2010;Narouee et al 2020). NSUM is an important method of sociological inquiry because knowing the size of a group is often a pre-requisite to understanding its social structure.…”