Hard-to-reach populations of men who have sex with men and sex workers: a systematic review on sampling methods.

Ana B Barros,Sonia F Dias,Maria Rosario O Martins

doi:10.1186/s13643-015-0129-9

Ana B Barros, Sonia F Dias + Show 1 more

Open Access

https://doi.org/10.1186/s13643-015-0129-9

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Abstract

BackgroundIn public health, hard-to-reach populations are often recruited by non-probabilistic sampling methods that produce biased results. In order to overcome this, several sampling methods have been improved and developed in the last years. The aim of this systematic review was to identify all current methods used to survey most-at-risk populations of men who have sex with men and sex workers. The review also aimed to assess if there were any relations between the study populations and the sampling methods used to recruit them. Lastly, we wanted to assess if the number of publications originated in middle and low human development (MLHD) countries had been increasing in the last years.MethodsA systematic review was conducted using electronic databases and a total of 268 published studies were included in the analysis.ResultsIn this review, 11 recruitment methods were identified. Semi-probabilistic methods were used most commonly to survey men who have sex with men, and the use of the Internet was the method that gathered more respondents. We found that female sex workers were more frequently recruited through non-probabilistic methods than men who have sex with men (odds = 2.2; p < 0.05; confidence interval (CI) [1.1–4.2]). In the last 6 years, the number of studies based in middle and low human development countries increased more than the number of studies based in very high and high human development countries (odds = 2.5; p < 0.05; CI [1.3–4.9]).ConclusionsThis systematic literature review identified 11 methods used to sample men who have sex with men and female sex workers. There is an association between the type of sampling method and the population being studied. The number of studies based in middle and low human development countries has increased in the last 6 years of this study.Electronic supplementary materialThe online version of this article (doi:10.1186/s13643-015-0129-9) contains supplementary material, which is available to authorized users.

Highlights

In public health, hard-to-reach populations are often recruited by non-probabilistic sampling methods that produce biased results
After screening titles and abstracts, 26 records were excluded for the reasons stated in the flow diagram, and the recruitment methods were identified in 205 publications
Most of the retrieved publications belong to the very high and high human development (VHHHD) regions (58 %), our review found that, in the last 6 years, the number of studies published based in middle and low human development (MLHD) countries increased more than those based in VHHHD countries (Table 5)

Summary

Introduction

Hard-to-reach populations are often recruited by non-probabilistic sampling methods that produce biased results. Hard-to-reach populations (HRP), hidden populations [1] or most-at-risk populations [2] are mainly associated with illegal or stigmatizing behaviours such as sex workers (SW), injection drug users (IDU), men who have sex with men (MSM) or homeless people [3, 4]. These groups are usually seen as key populations to be targeted as they have an important role on the spread of communicable diseases like HIV or tuberculosis [5,6,7]. Studying HRP presents several difficulties and challenges: (a) it is extremely difficult to use probability

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