Table 1.

Booster Study research activities and timescale

	−4 months	−3 months	−2 months	−1 month	−1 week	Main trial start	1 month	2 months	3 months	9 months
Invitation letter sent	✔
Interested individuals contact and screened for brief intervention eligibility		✔
Eligible participants are sent brief intervention		✔
Participant contacted for DVD use assessment			✔	✔
Participant contacted and screened for main trial eligibility					✔
Face-to-face appointment, consent, baseline assessment and randomisation						✔
Participant receives motivational interviewing (excludes control group)							✔	✔
Face-to-face follow-up appointment									✔
Face-to-face follow-up appointment										✔