Abstract
IntroductionThe results of the network scale-up (NSU) method in estimating the size of key populations for HIV might be biased if the recruited subjects are not fully informed of the risky behaviors of people in their networks (low visibility), or key populations have a smaller social network (low popularity). We aimed to measure such biases in the size estimation of people who inject drugs (PWIDs), and female sex workers (FSWs) in Iran.MethodsWe interviewed 163 male PWIDs, 76 FSWs (known as egos) and 600 subjects from the general population. We selected twenty first-names (ten males and ten females) and asked the study subjects separately how many people they knew with one of these names (known as alters). Visibility Factor (VF) was defined as the percentage of FSW or PWID alters that were aware of their behavior. In addition, the popularity factor (PF) was calculated by dividing the number of alters reported by FSWs and PWIDs into that of the general population. The 95% uncertainty intervals (UI) were calculated using bootstrap technique.ResultsThe VF was estimated at 54% (95% UI: 52%–56%) for PWID and 45% (95% UI: 42%– 48%) for FSW. The VF among the peer alters was significantly higher than non-peer ones. The PF for PWID and FSW was 69% (95% UI: 66%–73%) and 77% (95% UI: 72%–83%), respectively. The cross-validation and name splitting analysis showed that our estimates were not influenced by any single name.ConclusionsBoth correction factors, particularly VF were far from one, and NSU results without correction, could lead to up to 4 times underestimation of the sizes. Therefore, applying these coefficients is necessary in NSU projects.
Highlights
The results of the network scale-up (NSU) method in estimating the size of key populations for HIV might be biased if the recruited subjects are not fully informed of the risky behaviors of people in their networks, or key populations have a smaller social network
It is well known that the risk of transmitting HIV is extremely high among people who inject drugs (PWIDs) and female sex workers (FSWs) [3]; these key populations are hidden in the community due to the stigma surrounding their behaviors [4]
In order to estimate the proportion of variance in the number of alters known by each respondent which contributed to the estimation of popularity factor (PF), we modeled yijkwhere ‘y0 represented the number of known alters, ‘i0 the respondents, ‘j0 the selected names, and ‘k0 the group
Summary
The results of the network scale-up (NSU) method in estimating the size of key populations for HIV might be biased if the recruited subjects are not fully informed of the risky behaviors of people in their networks (low visibility), or key populations have a smaller social network (low popularity). Estimating the population size of hard-to-count subgroups is an important entity in the area of social science as well as in public health This is especially crucial in the HIV/AIDS context since reliable estimates of the size of key populations are one of the key pieces of information considered by policy makers; as such information could be used for better tracking the epidemic, program planning, advocacy and more effective resource allocations [1]. The need for this information is more prominent in a country like Iran with a concentrated HIV epidemic among people who inject drugs (PWIDs) and with limited resources as a middle income country [2]. Such challenges are even more prominent in a setting like Iran, with a dominant Islamic culture, and where stigma around sexual behaviors and its related subpopulations is high
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