Vitalum: development and evaluation of two innovative health communication technologies aimed at a combination of diet and physical activity changes among patients with high blood pressure and the general population.

Tailored Print Communications (TPC) and Telephone Motivational Interviewing (TMI) are both innovative and promising communication technologies that are being used to change regular physical activity and diet behaviour. Altering these behaviours is usefull when aiming at the reduction of elevated blood pressure, which continues to be a widespread major impediment to health. The 2 strategies are applied as instruments in the primary and secondary prevention of cardiovascular disease, i.e. participants include a sample of the general population and patients with hypertension, all recruited from databases of General Practitioners. The RCT will use a factorial design to test the (cost-) effectiveness of TPC, TMI and the combined effects of TPC and TMI, compared to the control group, who will receive a tailored letter after follow-up data are collected. Furthermore, the potential surplus value of TMI for lower SES groups will be tested. Four interventino actions are spaced over a one-year period. Cost effectiveness analyses focus on the most cost-effective method for achieving at least 10% improvement in at least one behavior and for achieving at least 1 guideline. This data will help policy makers to decide which approach deserves future dissemination.

1. Compared to participants in the control group, people receiving either Telephone Motivational Interviewing (TMI) or Tailored Print Communication (TPC):

a) increase fruit and vegetable intake by 10% from the expected mean at baseline;

b) decrease fat intake by 5%;

c) increase physical activity by 13%.

2. People receiving TMI+TPC have resulting behavioural changes which exceed the sum of the changes that are expected given each intervention.

3. Lower socio economic status groups benefit most from TMI.

4. Hypertensive patients are expected to be more motivated to change compared to the general public.

The Vitalum study has 4 trialarms:

1. Tailored Print Communication (TPC) group: this group receives four tailored letters;

2. Telephone Motivational Interviewing (TMI) group: this group receives four motivational interview phone calls;

3. Combined (TPC+TMI) group: this group receives two tailored letters and two telephone motivational interviews in turns;

4. Control group: this group receives a tailored letter after the second follow-up questionnaire.
Intervention activities are delivered in week 5, 13, 30 and 43 after the baseline questionnaire.