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

To study reactions of control group participants allocated to two different presentations of basic health information in a digital alcohol intervention trial.

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.

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%).

Being made to wait may invite negative research participation effects.

Comparator guidance should be updated to reflect the potentially negative consequences which are under researched.