Chronic pain, affecting over a quarter of the UK workforce, places a high economic burden on individuals, employers, and healthcare services. The Pain-at-Work (PAW) Toolkit is a digital intervention which aims to provide education and self-management advice to support employees with chronic pain in the workplace. There is evidence to demonstrate that text messaging can be used as an adjunct to health behaviour change interventions, in this case, promoting engagement with the PAW Toolkit.

All trial processes were conducted remotely, and communications between the trial team and the participants used email and optional text messages. Participants signed up and gave informed consent to participate via an online platform. Text messages were sent after trial registration to all participants to encourage completion of the surveys at baseline, 3 months and 6 months. In this cluster randomised controlled trial (cRCT), following the completion of the baseline survey, participants' workplaces were randomised to either intervention or control. Intervention participants had access to the PAW Toolkit for six months. They also received weekly text messages to promote engagement with the PAW Toolkit.

The text messages were developed using the COM-B model. This theory-based behaviour model addresses capability, opportunity, and motivation, leading to changes in the subsequent target behaviour. In this case, the target behaviour was engagement with the PAW Toolkit and the data collection surveys. One author initially drafted the messages mapped to COM-B, and then five others (four health psychologists and one pain researcher) provided input and reviewed them to ensure the presence of the required components. Consensus was achieved by discussion.

Twelve messages were developed for the intervention participants, one for each of the first 12 weeks of the trial, including a reminder to complete the 3-month survey. Two further reminders to complete the 6-month survey were sent at weeks 24 and 25. Nine messages were mapped to all three components of the COM-B model (capability, opportunity, motivation), and the remainder aligned with two COM-B components (opportunity, motivation). Text message content included motivational reminders to complete the surveys, engage with relevant Toolkit sections, enter a prize draw (optional) and get additional support from the trial team. Control participants received reminders to complete the surveys only.

Of 380 participants registered for the PAW Trial, 370 (97%) agreed to supply a mobile phone number for receiving texts relating to the trial. The baseline survey was completed by 310 participants (82%). Following cluster randomisation, 171 (55%) participants were allocated to the intervention and were sent the intervention text messages. Control text messages were sent to 139 (45%) participants. A sub-sample of text message recipients (n=67) completed 3-month evaluation and deemed the messages to be acceptable (58%) with over half indicating that the messages successfully prompted them to access the PAW Toolkit.

The theory-based text messages used in this trial were designed as an adjunct approach to promoting engagement with the intervention, the PAW Toolkit. This digital intervention offers valuable education and advice, but its success hinges on participant interaction. Our findings confirm that regular, targeted calls to action via text messaging can successfully prompt intervention engagement.

Keywords: Digital health, Chronic Pain, Workforce, Toolkit, Feasibility Trial, Education, Support, COM-B, Text messages.