Effect of a physician uncertainty reduction intervention on blood pressure in uncontrolled hypertensives--a cluster randomized trial.

Background: Clinical inertia, provider failure to appropriately intensify treatment, is a major contributor to uncontrolled blood pressure (BP). Some clinical inertia may result from physician uncertainty over the patient's usual BP, adherence, or value of continuing efforts to control BP through lifestyle changes.

Objective: To test the hypothesis that providing physicians with uncertainty reduction tools, including 24-h ambulatory BP monitoring, electronic bottle cap monitoring, and lifestyle assessment and counseling, will lead to improved BP control.

Design: Cluster randomized trial with five intervention clinics (IC) and five usual care clinics (UCC).

Setting: Six public and 4 private primary care clinics.

Participants: A total of 665 patients (63 percent African American) with uncontrolled hypertension (BP ≥140 mmHg/90 mmHg or ≥130/80 mmHg if diabetic).

Interventions: An order form for uncertainty reduction tools was placed in the IC participants' charts before each visit and results fed back to the provider.

Outcome Measures: Percent with controlled BP at last visit. Secondary outcome was BP changes from baseline.

Results: Median follow-up time was 24 months. IC physicians intensified treatment in 81% of IC patients compared to 67% in UCC (p < 0.001); 35.0% of IC patients and 31.9% of UCC patients achieved control at the last recorded visit (p > 0.05). Multi-level mixed effects longitudinal regression modeling of SBP and DBP indicated a significant, non-linear slope difference favoring IC (p (time × group interaction) = 0.048 for SBP and p = 0.001 for DBP). The model-predicted difference attributable to intervention was -2.8 mmHg for both SBP and DBP by month 24, and -6.5 mmHg for both SBP and DBP by month 36.

Conclusions: The uncertainty reduction intervention did not achieve the pre-specified dichotomous outcome, but led to lower measured BP in IC patients.