Table 1. SWAT outcomes.

Outcome	Type	Definition
Proportion of participants who return questionnaire (Primary Outcome)	Binary (returned/not returned)	Proportion of 14-week questionnaires returned to York Trials Unit. (Returns were censored at 11.06.2019)
Time to response	Time to event (days)	Number of days between the date the 14-week questionnaire was sent and the date the returned questionnaire was received by York Trials Unit.
Completeness of response	Continuous (0–5)	Number of completed responses to 5 key questions on the 14-week questionnaire.
Reminder notice sent	Binary (sent/not sent)	Proportion of participants sent a reminder questionnaire (sent three weeks after the initial questionnaire if no response had been received, no additional pens were sent with reminders).
Cost	Continuous	Consideration of cost effectiveness of pen inclusion