Abstract

Understanding the factors associated with participation is key in addressing the problem of declining participation rates in epidemiological studies. This review aims to summarise factors affecting participation rates in articles published during the last nine years, to compare with previous findings to determine whether the research focus for non-participation has changed and whether the findings have been consistent over time. Web of Science was used to search titles of English articles from 2007?2015 for a range of synonymous words concerning participation rates. A predefined inclusion criteria was used to determine whether the resulting articles referred to participation in the context of study enrolment. Factors associated with participation were extracted from included articles. The search returned 626 articles, of which 162 satisfied the inclusion criteria. Compared with pre-2007, participant characteristics generally remained unchanged, but were topic-dependent. An increased focus on study design and a greater use of technology for enrolment and data collection was found, suggesting a transition towards technology-based methods. In addition to increased participation rates, studies should consider any bias arising from non-participation. When reporting results, authors are encouraged to include a standardised participation rate, a calculation of potential bias, and to apply an appropriate statistical method where appropriate. Requirements from journals to include these would allow for easier comparison of results between studies.