IMPPACT: Investigation of Medical Professionals and Patients Achieving Control Together.

Objective: To determine whether home blood pressure monitoring (HBPM) led to physician-initiated medication titration and improved achievement of target BP levels compared with standard, office-based management.
Methods: Physicians were randomly assigned to a treatment group or a control group. Patients in the control group were monitored by their physician and were drug-adjusted according to the usual approach. In the treatment group, patients were given home BP monitors (UA-767P [A&D Medical/Lifesource, USA]), and drug dosing was adjusted according to HBPM readings and protocol. Long-acting diltiazem (240 mg/day) was added at baseline, which was adjusted as necessary (other medications were added if more than 360 mg/day of diltiazem was required). A final BP measurement was taken in the office after six weeks.
Results: Nineteen physicians were randomly assigned to the office BP monitoring group and 34 were assigned to the HBPM group. Of the 270 subjects recruited, 97 were in the office BP monitoring group and 173 were in the HBPM group. From baseline to the final visit, there was a statistically significant time by group interaction with lower BP in the HBPM group (P=0.034 for both systolic BP and diastolic BP). BP fell from 159/91+/-11/10 mmHg at baseline in the HBPM group to 138/80+/-13/8 mmHg on the final visit, and from 160/88+/-14/10 mmHg to 141/78+/-10/9 mmHg in the control group.
Conclusions: BP was lowered significantly in both groups, and to a statistically greater degree in the HBPM group. The Hawthorne effect might have led to altered care by the physicians with improvement in BP control in both groups.