Text Message Adherence Support for High Blood Pressure

Study Questions:

Can automated treatment adherence support delivered via mobile-phone text message improve blood pressure control?


This was a single-blind, three-arm randomized trial conducted in South Africa. Participants were patients treated for high blood pressure, with enrollment between June 2012 and November 2012. Participants were randomized in a 1:1:1 ratio to either information-only or interactive short message system (SMS) text-messaging; with a third group receiving usual care. The primary outcome was change in systolic blood pressure at 12 months from baseline. Intention-to-treat analysis was used.


A total of 1,372 participants were randomized to the three arms; information-only SMS text messages, (n = 457); interactive SMS test messages (n = 458); and usual care (n = 457). Mean (standard deviation) age was 54.3 (±11.5) years, >50% of participants were black, and 28% had at least 10 years of hypertension. Over one-half of the patients had a body mass index of at least 30 kg/m2. Other baseline characteristics were similar across the three groups. Nearly all the participants owned their own phone. Primary outcome data were available for 1,256 (92%) participants. At 12 months, the mean adjusted change (95% confidence interval [CI]) in systolic blood pressure compared to usual care was -2.2 mm Hg (95% CI, -4.4 to -0.04) with information-only SMS and -1.6 mm Hg (95% CI, -3.7 to 0.6) with interactive SMS. Odds ratios (95% CI) for the proportion of participants with a blood pressure <140/90 mm Hg were: for information-only messaging, 1.42 (95% CI, 1.03-1.95); and for interactive messaging, 1.41 (95% CI, 1.02-1.95), compared to usual care.


The investigators concluded that an automated adherence support program delivered by SMS text message in a general outpatient population of adults with high blood pressure, resulted in a a small reduction in systolic blood pressure control compared to usual care at 12 months. However, there was no evidence that an interactive intervention increased this effect.


Although this trial did not observe large improvements in blood pressure, it should be noted that among a real-world population, which included those with a range of socioeconomic levels, this intervention was feasible with a significant reduction in systolic blood pressure compared to usual care. Further refinement of the text-messaging intervention, grounded on sound behavioral therapy, may improve the impact of this intervention. Thus, eHealth interventions may be a component of global public health interventions to improve blood pressure.

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