Thirty-six studies (43,351 participants, range 30 to 13,100) were included: 21 were described as RCTs (16,312 participants), seven randomised prospective studies (19,750 participants), two open-label studies (1,729 participants), two longitudinal studies (4,765 participants), one cross-over study (31 participants), one pilot study (111 participants), one follow-up study (453 participants) and one study that comprised prospective observational and RCT phase (200 participants). Study duration lasted from three to 28 months.
Four RCTs and three prospective studies reported on informational interventions. Improvements were seen in some outcomes but there were no obvious patterns based on cardiovascular conditions and no long-term impact on adherence.
Seven RCTs, four prospective studies and four other studies reported on behavioural interventions. Home blood pressure monitoring (two studies) and regimen simplification (four studies) resulted in contradictory results for adherence and only some studies showed a significant beneficial effect. Six studies variously investigated motivational counselling, encouragement and reminders, regimen simplification and home blood pressure monitoring showed beneficial effects on blood cholesterols or blood pressure measure. Overall there were no obvious patterns in impact of the cardiovascular conditions. Twelve out of 16 studies with a duration greater than 12 months showed improvement in persistence and/or adherence; five out of 20 studies with a duration less than 12 months showed improvement in persistence and/or adherence.
One RCT (245 participants) assessed social interventions (nurse support). There were no significant effects on adherence or blood pressure measures.
Nine RCTs and four other studies reported on combined interventions. Most included informational and behavioural interventions, three included informational and social interventions and one combined all three types. Improvements were seen in some studies for adherence or other outcomes and in other studies there was no effect. There were no obvious patterns in positive effect based on cardiovascular conditions.