Unblinding following trial participation: Qualitative study of participants' perspectives.

Background: The implications of offering unblinding to trial participants to treatment arm after trial completion have been little explored. Purpose: We sought to explore trial participants’ perspectives on whether they would like to be unblinded as to the treatment arm to which they were allocated following involvement in a large randomised controlled trial (RCT). Methods: We conducted semi-structured interviews with 38 women who had participated in a trial during suspected preterm labour and had received the results of a long-term follow-up study that identified adverse outcomes for children in some of the treatment groups. Participants were sampled purposively. Analysis was based on the constant comparative method. Results: Most women reported that they wanted to know the treatment arm to which they had been allocated. While the primary motive for some was curiosity, many others wanted to know as part of an attempt to understand or explain their child’s current health problems. These women were motivated by a search for a coherent causal narrative, even though unblinding was unlikely to be able to meet their aspirations. Some participants identified potential disadvantages in discovering their treatment allocation, including feeling responsible for their child’s health status, and some women were very clear that they did not want to know their treatment group. Limitations: A purposive sample was used and the extent to which it represents the views of all participants in the study is not established. Conclusions Important challenges arise in offering to unblind trial participants, whatever the trial results. Participants may need help and support to understand the limitations of the knowledge they gain through being unblinded and to decide whether they wish to know to which treatment arm they were allocated.