Pilot implementation of short message service for randomisation in a multisite pragmatic factorial clinical trial in...

The traditional use of sealed envelopes for randomisation is susceptible to manipulation and the risk of damage to envelopes during shipping and storage. Additionally, the filling and sealing of envelopes are tedious, time-consuming, and error-prone. Other randomisation alternatives such as web-based methods are preferred. However, they are expensive and unsuitable in settings with poor internet infrastructure. Mobile phone-based randomisation using short message service (SMS) potentially offers a low-cost and reliable alternative.

We developed an SMS-based method for random allocation of treatments. Plain text messaging or an Android app was used to formulate text messages using a fixed syntax consisting of the participant's unique identifier, trial site, stratum, and the trial name as input parameters. The system verified the input parameters and obtained an allocation from the database before returning a response to the sender. The text response contained the details of the treatment allocation. This was a Study Within A Trial (SWAT) conducted in two sites of a multi-site 3 × 2 factorial clinical trial in Kenya involving two interventions with up to nine possible allocations. SMS randomisation feasibility was assessed by comparing treatment allocations against the master randomisation list for each processed SMS, measuring SMS latency (in seconds), and gathering user feedback via a post-implementation survey.

A total of 218 participants were randomised between the 7th of February 2022 and the 11th of April 2022, out of which 179 were randomised to only one arm while 39 were randomised to both treatment arms. Allocation accuracy was 100%. Median latency was 22 s with the fastest message processed in 10 s and the slowest (non-network delayed) message processed in 2129 s. Four users completed a post-implementation survey.

The pilot study demonstrated that SMS randomisation is easy, user-friendly, fast, accurate, and a feasible alternative randomisation technique.