Table 9 Changes following Phases I, II, and III stakeholder feedback

• Participants should be reminded that they do not have to answer any questions that they do not want to; their responses are voluntary

• Where possible, terminologies used to describe the psychometric assessments should be altered to reduce stigma without compromising the reliability of the measure

• Staff should remind participants that they were entitled to take breaks whenever they choose, and that researchers should work at the participants’ pace

• The ‘treatment as usual’ form should be moved to the end of the study, so as to support the movement back to more general discussions as this was felt to be a more natural way to bring discussions to an end. This should be followed by asking participants what they planned to do once they are discharged from hospital

• Researchers should be reminded to consistently risk assess participants throughout the psychometric assessment completion phase, to ensure that asking the questions does not have a negative effect on participant wellbeing

• Participants should be provided with envelopes to keep their Safety Plan and other study materials safe and discrete. Participants should also be asked if they would like to take a picture of their safety plan on their phones so that it is visually available to them at all times

• Participants’ study documents (safety plan, consent form, participant information sheet) should be sealed in a green envelope to help it stand out from other hospital discharge documents

• Researchers should offer additional copies of the Safety Plan to participants following each follow-up call to facilitate the use of the Safety Plan

• The script for the first follow-up call should be amended to acknowledge that participants may have forgotten aspects of their baseline contribution to the study, including how to use the Safety Plan. This amendment should include offering to explain the function of the safety plan again

• Researchers should continue to remind participants that they can edit the safety plan at any point, and that it is a dynamic document

• Researchers should remind participants that others have found the Safety Plan to be of benefit, so we hope that it may also be of personal benefit to them

• Researchers should check that prospective participants have both been risk assessed and notified about the study so they can indicate if they wish to be approached initially

• Researchers should intermittently check-in with NHS referral staff to ensure existing operating procedures (e.g. times for telephone calls to check eligibility) continue to be at a suitable time

• Minor changes to the CRF were suggested, to help clarify TAU (e.g. in-patient vs out-patient psychological support) and mental health diagnoses (e.g. anxiety vs. PTSD)

• A coping measure (Suicide-Related Coping Scale (SRCS)) to explore coping styles of the participants at baseline should be incorporated into the protocol

• A brief one-page bullet point summary of the content of the PIS (what is involved in the study and participants’ rights) to accompany the PIS should be developed

• A tutorial video (e.g. using YouTube, Vimeo, with no option for participants to add comments below the video) detailing the Safety PIanning Intervention (SPI), what is involved, level of flexibility, and the parameters of the interventions (what the SPI is and is not) should be developed. This could be sent to participants via text for them to watch in their own time. Researchers should inquire and record whether participants used the video during the follow-up calls

• It would be useful to examine how participants relate to SPI engagement, perhaps using data already collected in the CRF (e.g. controllability of suicidal thoughts item in CSSRS; ENQ; SCRS)

• Consider providing a handwritten (or sticker) reminder of the name and telephone number that will be used to call participants (mobile and desk number) on the green envelopes. This may improve follow-up telephone call engagement, particularly at the initial 72-h call point

• The first call (within 72 h of baseline assessment) could be considered a ‘touching base’ contact, where participants are informed about the structure of each call, flexibility regarding calls, etc. and invited to review their Safety Plan (may be especially beneficial for those who have difficulty remembering their Safety Plan from baseline in hospital)

• Research team should determine parameters regarding personalisation of SPI and flexibility of calls (e.g. absolute max. and min. time between calls, number of extra calls offered) as these should be standardised across all sites according to the study protocol

• The Safety Plan script should be updated to explicitly ask for likelihood of use and barriers at each step. To ensure this, quarterly fidelity checks of Safety Plan recordings using the official Safety Plan Fidelity Monitoring Checklist should be conducted