THE EFFECT OF TEXT MESSAGES BY CELL PHONE IN THE CONTROL OF HYPERTENSION: A RANDOMIZED CLINICAL TRIAL

Abstract

Objective: To compare the effects of texting by cell phone plus standard usual guidance for hypertension versus standard usual guidance alone, on blood pressure control, among hypertensive patients undergoing outpatient treatment. Design and method: Randomized controlled clinical trial, composed of two groups: Intervention Group, who received SMS text messages twice a week for 10 weeks; and Comparison Group, who received the usual care. Both groups received an educational pamphlet about the hypertension. The primary outcome was BP control by office blood pressure measurement (OBPM; <140/90 mmHg) or by daytime Ambulatory Blood Pressure Monitoring (ABPM; <135/85 mmHg). Adherence to treatment was assessed indirectly using the 4 item Morisky Medication Adherence Scale and, directly, by assessing antihypertensive drugs in the urine, using a high-performance liquid chromatography technique associated with mass spectrometry. The significance level was 5%. Results: In the study, 178 patients were randomized, (90 in the Intervention Group and 88 in the Comparison Group). The sample was 60 (10) years old, women (63.8%), non-white (58.9%) and married (54.6%). The hypertensive patients were classified as having high cardiovascular risk (77.3%). The result of the intervention effect showed that there was no difference between the Intervention Group and Comparison Group (RR = 1.05; 95%CI = 0.75-1.47, and RR = 1.23; 95%CI = 0.87-1.74, respectively) in the control of OBPM, or by the daytime ABPM. However, in the Intervention Group and Comparison Group, respectively, there was a mean reduction in BP (-8.6 and -7.3 mmHg in systolic OBPM and -2.19 mmHg and -2.09 mmHg in systolic daytime ABPM); and increase in the BP control by the OBPM (19.8% to 36.0% and 19.7% to 38.2%) and daytime ABPM (38.6% to 42.5% and 41.3% to 52.2%); and in the assessment of adherence indirectly (45.3% to 69.4% and 57.1% to 59.2%). In the assessment of adherence directly, there was little difference between the groups and the two moments evaluated. Conclusions: The effect of texting by cell phone was similar to usual treatment for hypertension on BP control. On the other hand, both groups improved BP control and increased adherence to treatment.