Fig. (1) Percentage and ranking of barriers to recruitment. Study participants were asked to select all potential barriers to recruitment from a pre-established list, and then to rank order the barriers they had identified. While some barriers had equal percentage and ranking scores (sensitive nature of the research topic was ranked highest and was identified by the most percentage, 59% of respondents). Other barriers were ranked lower than the frequency at which they were identified by respondents (transportation costs was ranked 10th despite being selected by 41% of respondents).