The txt4healthyhearts mobile phone based intervention to reduce LDL cholesterol in patients at high risk of a cardiovascular event: intervention development.

Talk Code: 

The problem

In patients at high risk of coronary heart disease medications reduce mortality and cardiovascular events, but many people don't adhere to their medication. Systematic reviews show that effective interventions to increase adherence are multifaceted, but are too costly or impractical for widespread implementation. Multifaceted interventions delivered by mobile phone could increase adherence to secondary prevention medications. In particular, they could increase adherence to statins reducing LDL cholesterol. We describe the development of our multi-component intervention delivered by text message.

The approach

We developed our intervention based on the COM-B theory of behaviour, theory of behaviour change, evidence regarding the factors influencing adherence and user views. We conducted a systematic review of factors influencing adherence to medications for the prevention of heart disease and listed factors linked to adherence reported in existing systematic reviews. We wrote messages to influence each modifiable factor employing relevant intervention functions and using relevant behaviour change techniques selected from Michies' comprehensive taxonomy of behaviour change techniques. To ensure the intervention is acceptable, accessible (comprehensible) and relevant to UK patients we recruited 19 patients at high risk of coronary heart disease from primary or secondary care services. Participants were interviewed about their experience of taking medications for the prevention of heart disease and the factors influencing their medication adherence. Participants were sent the preliminary messages via our automated and interactive text messaging system. They were contacted by telephone for a second interview about the accessibility (comprehensibility), acceptability, relevance and impact of the messages.


According to our conceptual framework adherence to medication is influenced by knowledge reagarding the benfits of medicines and how to take them, beliefs regarding the necessity for medication, concerns regarding medicines, practical barriers to taking medicines, habit formation, self-efficacy and skills, which have important effects on motivation, capability and opportunity. In addition social influences such emotional and practical support from friends and family and health care provision influence these factors. Our intervention aims to alter these factors to increase adherence to medications prescribed for the secondary prevention of heart disease employing eight behaviour change techniques. Participants reported that messages were easy to understand, reassuring and helped them remember what was important about taking their medication. They reported re reading and reflecting on messages and sharing them with relatives and friends. They reported that messages about other peoples' experiences in taking medication were particularly helpful. One person found the messages were too frequent and consequently irritating. Participants reported that the messages increased their motivation to take medicines.


We have developed a multi-component intervention delivered by mobile phone which is acceptable, accessible and relevant to patients. We will conduct a trial to establish the effects of text messages based adherence support on LDL cholesterol.


  • Caroline Free, UCL, London, UK
  • Ona Mccarthy, UCL, London, UK
  • Tim Clayton, UCL, London, UK
  • Rob Horne