Reactions to being allocated to a waiting list control group in a digital alcohol intervention trial

OBJECTIVE: To study reactions of control group participants allocated to two different presentations of basic health information in a digital alcohol intervention trial. METHOD: Control participants were randomised to wait with one of two different presentations of basic health information. Multiple choice questions and free-text comments assessed reactions, four months post randomisation. Effects of differential health information on responses were estimated, as were associations between responses, baseline characteristics and change in alcohol consumption. RESULT: Of 1066 control group participants, 572 (54%) responded to the questionnaire. Contrasting two different presentations of basic health information revealed no statistically significant differences. Responses revealed that 38% were interested sufficiently to look at the information while 42% felt frustration, irritation, or disappointment about having to wait. Approximately 55% responded that they decided to reduce their drinking whilst 17% stated that they continued to drink as usual, and 11% gave up on the idea of reducing their drinking. The two latter groups reported markedly higher alcohol consumption at follow-up in comparison to the former (probability of association >99.9%). CONCLUSION: Being made to wait may invite negative research participation effects. PRACTICE IMPLICATION: Comparator guidance should be updated to reflect the potentially negative consequences which are under researched.