This trial will be a 6-month prospective, randomised controlled trial in which the study population is randomly allocated (1:1) to an intervention or control group. The trial is multicentre and is non-blind. All patients in both groups will continue to receive their usual care for the duration of the study. Randomisation will be at the individual level. Participants will be randomly allocated as per a computer-generated randomisation list using a random number generator as part of the Microsoft .NET framework.
This is a behavioural intervention. The intervention will consist of a series of supportive text messages to patients from their GP practice over a 6 month period. The messages will vary in frequency from 2 or 3 in the first weeks of the trial to only 1 or 2 a month in the final months of the trial. The content of the messages will vary; some will contain information about how to use a preventer inhaler, some will emphasise the importance of using it, and some will provide simple reminders to patients to take their inhaler.
All participants will continue to receive their usual care throughout the duration of the study; the text message intervention with be in addition to their usual care.
