Does handwriting the name of a potential trial participant on an invitation letter improve recruitment rates? A randomised controlled study within a trial

Abstract

Background: Randomised controlled trials (RCTs) often fail to recruit to target, resulting in a lack of generalisability of findings. A wide range of strategies for potentially increasing recruitment have been identified; however, their effectiveness has not been established. The aim of this study within a trial (SWAT) was to evaluate the effectiveness of handwritten personalisation of an invitation letter as part of a trial recruitment pack on recruitment to a host RCT. Methods: A pragmatic, two-armed RCT was conducted, embedded within an existing falls prevention trial (OTIS) in men and women aged 65 years and over living in the community. Participants were randomised 1:1 to receive an OTIS recruitment pack containing an invitation letter on which their name was handwritten (intervention group), or one on which it was printed (control group). The primary outcome was randomisation into the host trial. Secondary outcomes related to trial eligibility and retention. Analyses were via logistic regression and Cox Proportional Hazards regression. Results: Of the 317 SWAT participants, 12 (3.8%) were randomised into the OTIS trial: 3 (handwritten: 3/159 [1.9%]; printed: 9/158 [5.7%]; difference -3.8%, 95% CI -8.0% to 0.4%). There was weak evidence, against the intervention, of a difference in the likelihood of participants being randomised into the host trial between the two groups (OR 0.32, 95% CI 0.08 to 1.20, p=0.09). There were no statistically significant differences between the intervention and control groups on any of the secondary outcomes. Conclusions: There was no evidence that personalisation of invitation letters improved recruitment to the OTIS trial. However, due to the small sample size, the results should be interpreted with caution. These findings need to be replicated across larger studies and wider populations. Registration: ISRCTN22202133.

Do recruitment SWAT interventions have an impact on participant retention in randomised controlled trials? A systematic review

“…Four SWATs (40%) used unequal randomisation, 19,21,23,27 with the majority (n = 3; 75%) favouring the SWAT control arm. 19,21,23 In line with the Online Resource for Recruitment research in Clinical Trials categorisation, and as detailed in Table 1, the majority of SWATs focussed on the information given to participants (n = 6, 60%), [22][23][24][25][26][27] including modifications to patient information sheets (n = 2), modifications to invitation letters (n = 2), modifications to both (n = 1), and provision of a research information leaflet (n = 1). The remaining SWATs focussed on incentives (n = 2, 20%), 18,19 and trial design (n = 1, 10%) 21 and recruiter interventions (n = 1, 10%).…”

Home environmental assessments and modification delivered by occupational therapists to reduce falls in people aged 65 years and over: the OTIS RCT

“…As we planned to mail out a large number of invitation packs in order to recruit sufficient participants, we took the opportunity to evaluate the effectiveness of interventions designed to increase recruitment to studies. 23,24 As we were sending out large numbers of postal questionnaires to participants for follow-up data, we also took the opportunity to evaluate interventions aimed at improving response rates to postal questionnaires. 25,26 Any potential participant identified using one of the above strategies was sent a study recruitment pack consisting of an invitation letter (see Report Supplementary Material 1), a participant information sheet (see Report Supplementary Material 2), a consent form (see Report Supplementary Material 3), a screening questionnaire (see Report Supplementary Material 4) and a freepost envelope for returning the completed paperwork.…”

The effect of personalised versus non-personalised study invitations on recruitment within the ENGAGE feasibility trial: an embedded randomised controlled recruitment trial

“…One potential way of optimising recruitment is the personalisation of trial documentation, with a systematic review suggesting personalisation can improve questionnaire return rates [19]. However, this review included a wide variety of personalisation strategies, for example, signing letters personally and hand-addressing envelopes making it difficult to know which personalisation strategy/ies may have a positive effect on recruitment [20]. Further, the current literature has predominantly focused on returning questionnaires or surveys [21][22][23] and very few studies utilising a RCT design, have been conducted within the context of healthcare intervention research, to examine the personalisation of study invitations on recruitment rates [24].…”