Efficacy of a Brief Intervention on Reduction of Systolic Blood Pressure

This study examines the efficacy of individualized counseling letters to reduce systolic blood pressure level of ≥ 130 mmHg in individuals aged between 40 and 65 years. The computer-generated counseling letter intervention aimed to increase moderate-to-vigorous physical activity, to reduce sedentary time, and to achieve smoking abstinence. Participants are recruited by nurses in routine care of primary medical practices.

Informed consent consists of: (i) participation in standardized measurement of blood pressure as well as waist and hip circumference at baseline and 12-month follow up, (ii) completion of standardized questionnaires at 4 time points (baseline, 4-month, 7-month, and 12-month follow-up). Participation in accelerometry was defined as an option. Individuals who agree to wear the accelerometer do this for 10 days at baseline and 12-month follow-up, each.

After baseline assessment, individuals are randomly allocated to a control and to an intervention group (ratio 1:1).

Intervention: The computerized intervention system includes three interactions with participants aiming to increase moderate-to-vigorous physical activity and to reduce sedentary time. For individuals who were daily smokers at baseline, the computerized intervention system includes three more interactions with participants aiming to foster the motivation to quit smoking. Recurrent assessments are initiated by the system and provide data for scheduling the proceeding intervention steps and selection of relevant content. Physical activity, sedentary time, smoking, and motivational measures to change or maintain behaviors according to the recommendations will be monitored over time and used to provide feedback in the form of letters.

Intervention group: Individuals in this group complete a tablet PC-supported assessment at baseline and 12-month follow-up, both at the general practice. At months 4 and 7, follow-up data are collected by study team members via phone call. According to the assessments (baseline, month 4, and month 7), participants receive three counseling letters aiming to increase moderate-to-vigorous physical activity and to reduce sedentary time. Additionally, individuals who were daily smokers at baseline, receive three counseling letters aiming to foster the motivation to quit smoking. The first letter is accompanied by a self-help manual covering specific information relevant for the particular stage of motivation to change smoking behavior according to the principles of the Transtheoretical Model of behavior change.

Control group: Individuals in this group complete a tablet PC-supported assessment at baseline and 12-month follow-up, both in the general practice. At months 4 and 7, follow-up data are collected by study team members via phone call.