Providing insights on refusal to participate in research is critical to achieve a better understanding of the non-response bias. Little is known on people who refused to participate, especially in hard-to-reach populations such as detained persons. This study investigated the potential non-response bias among detained persons, comparing participants who accepted or refused to sign a one-time general informed consent. We used data collected in a cross-sectional study primary designed to evaluate a one-time general informed consent for research. A total of 190 participants were included in the study (response rate = 84.7%). The main outcome was the acceptance to sign the informed consent, used as a proxy to evaluate non-response. We collected sociodemographic variables, health literacy, and self-reported clinical information. A total of 83.2% of the participants signed the informed consent. In the multivariable model after lasso selection and according to the relative bias, the most important predictors were the level of education (OR = 2.13, bias = 20.7%), health insurance status (OR = 2.04, bias = 7.8%), need of another study language (OR = 0.21, bias = 39.4%), health literacy (OR = 2.20, bias = 10.0%), and region of origin (not included in the lasso regression model, bias = 9.2%). Clinical characteristics were not significantly associated with the main outcome and had low relative biases (≤ 2.7%). Refusers were more likely to have social vulnerabilities than consenters, but clinical vulnerabilities were similar in both groups. The non-response bias probably occurred in this prison population. Therefore, efforts should be made to reach this vulnerable population, improve participation in research, and ensure a fair and equitable distribution of research benefits.
Copyright: © 2023 Baggio et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.