SWAT 137: A 2x2 randomised factorial SWAT of the use of a pen and brief information leaflet to improve recruitment in a randomised controlled trial of a community-based clinic for patients with persistent physical symptoms [version 1; peer review: awaiting peer review]

Background Many strategies are used by trialists to improve recruitment, but few have been tested. We aimed to evaluate two interventions: 1) a study branded pen and 2) brief participant information leaflet, included within invitation packs for the Multiple Symptoms Study 3 (MSS3) trial. Methods A 2x2 factorial ‘study within a trial’ (SWAT) embedded into MSS3 – a randomised trial of a community-based clinic for patients with persistent, medically unexplained, physical symptoms. Potential MSS3 participants received postal invitations sent via GP practices, along with a MSS3 branded pen and/or brief participant information leaflet (PIL) or neither. The primary outcome was randomisation rate. Secondary outcomes were return rate, time to return, reasons for non-randomised returns and cost-effectiveness. Results 108 GP practices posted 6946 invitations, from which 318 participants (4.6%) were randomised to the host trial. Between those sent a brief PIL (n=3467) and not sent a brief PIL (n=3479) there was no significant difference in randomisation rates (166 (4.8%) vs 152 (4.4%); OR 1.10, 95% CI 0.88-1.38). Response rates were significantly higher in those sent the brief PIL (573 (16.5%) vs 513 (14.7%); OR 1.14, 95% CI 1.01-1.30). Between those sent the pen (n=3464) and not sent the pen (n=3482) there was no evidence of increased randomisation (145 (4.2%) vs 173 (5.0%); OR 0.84, 95% CI 0.67-1.05) and the difference in response rates was not statistically significant (563 (16.3%) vs 523 (15.0%); OR 1.10, 95% CI 0.96-1.25). For both SWAT interventions, time to response was comparable between groups. Conclusion There was no significant evidence of effectiveness of the brief PIL intervention or the pen intervention on recruitment to the host study. There was evidence of increased response rates to the initial invitation in the brief PIL group, compared to those not receiving a brief PIL in their invitation pack