JMIR Publications

ABSTRACT

Background:

Randomised controlled trials (RCTs) with no in-person contact (i.e. remote) between researchers and participants offer savings in terms of cost and time, but present unique challenges.

Objective:

We examine differences between different forms of remote recruitment [e.g. National Health Service (NHS) website, social media and radio advertising] in the proportion of participants recruited, demographic diversity, follow-up rates, and cost. We also examine the cost-per-participant of sequential methods of follow-up (emails, phone calls, postal surveys and postcards).

Methods:

A descriptive analysis of 5,602 increasing-and-higher-risk drinkers (Alcohol Use Disorders Identification Test score ≥ 8), taking part in a two-arm, parallel group, remote RCT with a 1:1 allocation comparing the intervention (Drink Less app) with usual digital care (NHS alcohol advice webpage). Participants were recruited between July 2020 and March 2022 and compensated with gift vouchers of up to £24 for completing follow-up questionnaires, and an additional £12 if the 6-month survey was completed within 24 hours.

Results:

The three main recruitment methods were adverts on i) social media (44%), ii) NHS website (35%), and iii) radio/newspaper (13%), with remaining methods of recruitment accounting for less than 10% of the sample. Cost-per-participant varied (£0-£11.01). Costs were greater when recruiting participants who were men (£0-£28.85), from an ethnic minority (£0-£303.81) and more disadvantaged (£0-£49.12). Targeted approaches were useful for recruiting more male participants, but less useful in achieving diversity in ethnicity and socioeconomic status. Follow-up at 6-months was 80%. Of those who responded, 92% responded following emails. Each additional stage of follow-up resulted in an additional 2-3%, though phone calls, postal surveys and postcards were more resource-intensive than email reminders.

Conclusions:

For remote RCTs, researchers could benefit from: using a range of recruitment methods and costing for targeted approaches to achieve demographic diversity. Automated emails with substantial financial incentives for prompt completion can achieve good follow-up rates and sequential, offline follow-up options, such as phone calls and postal surveys can further increase follow-up rates but are comparatively expensive. Broader recommendations are also discussed. Clinical Trial: https://www.isrctn.com/ISRCTN64052601