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Treatment Intensification Improves Blood Pressure Control Both in Adherent and Non-Adherent Patients
Rose AJ, Berlowitz DR, Manze M, Orner MB, Kressin NR. Treatment Intensification Improves Blood Pressure Control Both in Adherent and Non-Adherent Patients. Paper presented at: Society of General Internal Medicine Annual Meeting; 2009 May 13; Miami, FL.
BACKGROUND: Treatment intensification (TI) can improve blood pressure (BP) control in hypertensive patients. When clinicians suspect nonadherence, they may be reluctant to intensify therapy, but there is no evidence regarding whether patients with less than ideal adherence would benefit from TI. Our objective was to investigate whether the impact of TI upon BP control varies by adherence to therapy.
METHODS: Our prospective cohort study enrolled patients with hypertension, managed in primary care at an academic, inner-city safety net hospital. We used the following formula to characterize TI: (visits with a medication change - visits with elevated BP)/total visits. Adherence to therapy was measured at baseline using electronic caps that record pill bottle openings ("MEMS caps"). Patients were dividied into 4 adherence strata based on MEMS data: "excellent adherence" (over 90% of days adherent), "fair adherence" (60-90%), "poor adherence" (below 60%), and patients who did not return their MEMS. We examined the relationship between TI and the final systolic blood pressure (SBP), controlling for patient-level covariates, using a three-step process. In the first step, we characterized the relationship between TI and BP in the entire sample. In the second step, we characterized the relationship between TI and BP only among patients with excellent adherence. Finally, we used interaction terms to test whether the effect of TI upon BP in the other adherence strata (fair, poor, and missing adherence) differed from the effect size among patients with excellent adherence.
RESULTS: 819 patients were followed for an average of 24 months. Their mean age was 60, 66% were female, and 58% were of Black race. The mean baseline and final BP values were 134/80 mm/Hg and 133/79 mm/Hg. 391 patients had excellent adherence, 201 patients had fair adherence, 77 patients had poor adherence, and 150 patients had missing adherence. Among the sample as a whole, each additional therapy increase per 10 visits predicted a 2.2 mm/Hg decrease in the final SBP (p < 0.001). Among patients with excellent adherence, each additional therapy increase per 10 visits predicted a 1.9 mm/Hg decrease in the final SBP (p < 0.001). Among patients with fair adherence, each therapy increase predicted a 2.6 mm/Hg decrease in the final SBP, but this effect size was not significantly different from the excellent adherence group at the 0.05 level (p = 0.056). The effect sizes in the poor and missing adherence groups were a 2.1 and a 1.7 mm/Hg decrease in the final SBP for each additional therapy increase, but these effect sizes were not significantly different from that of the excellent adherence group (p = 0.60 and 0.66, respectively). No episodes of hypotension were reported to the data safety monitoring board.
CONCLUSION: Patients with excellent adherence, fair adherence, poor adherence, and even patients who did not return their MEMS caps all benefited from intensification of antihypertensive therapy to a similar extent. Clinicians should not await proof of perfect adherence before intensifying therapy for uncontrolled hypertension.