The traditional use of sealed envelopes for randomisation is susceptible to manipulation and the risk of damage to envelopes during shipping and at storage. Additionally, the filling and sealing envelopes is, 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 were used to formulate text messages using a fixed syntax consisting of participant 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. The study was done in two sites of a multi-site 3x2 factorial clinical trial in Kenya involving two interventions with up to nine possible allocations. We evaluated the accuracy of treatment allocations against the master randomisation list for each randomisation SMS processed, and SMS latency in seconds. A post-implementation survey was conducted to evaluate user feedback. A total of 218 participants were randomised between 7th February 2022 and 11th 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 seconds with the fastest message processed in 10 seconds and the slowest (non-network delayed) message processed in 2129 seconds. Four users completed a post-implementation survey. The pilot study demonstrated that SMS randomization to be easy, user-friendly, fast, and accurate and a feasible alternative randomisation technique.

The authors have declared no competing interest.

Yes

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The Kenya Medical Research Institute (KEMRI) Scientific and Ethics Review Unit approved the collection of the deidentified data analyzed in this study.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

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I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

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The data utilized in this work was generated from the SMS randomization system. Further access to the data and additional system design materials can be sought through a request to KEMRI Wellcome Trust Research Programme’s Data Governance Committee through email: dgc@kemri-wellcome.org.