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SMS-text Adherence Support (StAR) Study. A qualitative evaluation of a mobile-phone based programme to enhance adherence to health care for hypertension in Cape Town


High blood pressure is the leading risk factor for global disease burden, and is associated with more than 9 million deaths a year worldwide. Level of blood pressure is directly associated with cardiovascular events and overall mortality risk, and lowering blood pressure reduces these risks. A substantial contribution to the burden of disease associated with high blood pressure comes from sub-optimal adherence to effective treatments.

Face-to-face interventions to support treatment adherence are costly, and resources are limited in low- and middle-income settings. Delivering support via SMS text messaging is a theoretically promising approach to this problem, but robust evidence from trials with clinically robust outcomes is limited. A smoking cessation intervention delivered by SMS messages produced a small increase in quit rate at 6-months, and an intervention to support adherence to anti-retroviral therapy using SMS text increased adherence but also required follow-up telephone calls to participants potentially limiting the generalisability of the intervention. Extending this approach to other major long-term conditions needs to focus on automated, multifactorial interventions that can be delivered at scale and provide evidence about sustainability.

study design

The SMS-text Adherence support trial (StAR) tests the efficacy of a behavioural intervention delivered via SMS text message to support adherence to blood pressure treatment compared to usual care. The intervention is a structured programme of educational and motivational messages, behaviour-change support, and clinic appointment and medication pick-up reminders. These messages were developed with patients and clinic staff in a series of focus groups and signed to address a range of barriers to treatment. The tone and content of the messages were endorsed by the patient group. The messages were delivered remotely using an automated system of semi-tailored, information only or interactive SMS text messages delivered to 1372 enrolled participants.

The technical infrastructure developed for the StAR trial includes mobile device-based electronic data collection at the point of care with secure remote upload of the data; the intervention delivery system; real-time query identification for screening, enrolment and participant management procedures; and monitoring and evaluation of trial processes. Open-source software platforms are used in conjunction with off-the-shelf hardware. Participants are randomly allocated to receive the trial intervention or usual care, data collection is blind to allocated group and independent statistical analysis will be carried out according to a pre-defined plan.  

Delivery of treatment adherence support via automated mobile-phone text messages have potential to be an important new addition for improving the treatment of hypertension in low-income and middle-income settings with a low cost for delivering the intervention.

This trial is the largest to date in middle- and low-income settings, and the largest trial of an SMS intervention ever done outside the field of smoking cessation. The Wellcome Institutional Support Fund has funded a policy evaluation of the impact of the intervention (currently in progress) and GACD and MRC UK has funded a further study in sub-Saharan Africa using the technology to explore wider scale-up for supporting treatment of type 2 diabetes.

See also our Primary Care for the Developing World pages for more information.

results now published

Please see GACD and University of Oxford Mobilising Against Hypertension pages for further information about the study.  See Publications link for list of publications. 

Full project title:

SMS-text Adherence Support (StAR) Study. A qualitative evaluation of a mobile-phone based programme to enhance adherence to health care for hypertension in Cape Town

Funded by:

Wellcome Trust Logo     


  • Natalie Leon (SAMRC)
  • Rebecca Surender (Oxford University)
  • Jocelyn Muller (SAMRC)
  • Kirsty Bobrow (UCT and Oxford University)
  • Andrew Farmer (Oxford University)


  • University of Oxford (Nuffield Department of Primary Care Health Sciences, Department of Biomedical Engineering).
  • University of Cape Town
  • South Africa MRC
  • Chronic Diseases Initiative Africa.


  • University of Oxford