An incremental model to isolate specific effects of behavioral treatments in essential hypertension

To prove clinical effectiveness of behavioral treatments in essential hypertension, an incremental repeated measures design was combined with findings that positive expectancies (placebo factors) potentiate specific effects. If positive expectancy effects were maximized in a Baseline Control Phase (6-26 weeks of BP stabilization), specific effects might be isolated as well as potentiated in a Learning Phase (2a, 6 weeks, twice/week; 2b, 6 weeks, once/week--fading). Follow-up Phase 3 was six weeks, once/week; six months, once/month; and at 12 months. To equalize groups across seasons over 12 years of regular clinical work, 117 volunteer outpatient veterans with borderline to moderate essential hypertension (130-170/90-110) were assigned in order of entry (10-20 each year) to one of four R, simple relaxation; REMG, R + EMG biofeedback; BP, BP biofeedback only; RBP, R + BP; or to an inert Control Group (TA, reading about transactional analysis without skills training). The four Treatment groups showed modest but consistent BP decreases during Phase 2 (p range from .0001 to .01). Control Phase placebo effects matched those in the Control Group (no BP decrease after Baseline). With a two-way mixed ANOVA design, Learning Phase 2 isolated specific effects of behavioral treatments, while the Control Phase 1 with liberal placebo factors potentiated specific effects during regular clinical work.