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Methods Papers

Comparing Methods of Measuring Treatment Intensification in Hypertension Care

Adam J. Rose, MD, MSc; Dan R. Berlowitz, MD, MPH; Meredith Manze, MPH; Michelle B. Orner, MPH and Nancy R. Kressin, PhD

From the Center for Health Quality, Outcomes, and Economic Research (A.J.R., D.R.B., M.B.O., N.R.K.), Bedford VA Medical Center; the Department of Medicine, Section of General Internal Medicine (A.J.R., D.R.B., M.M., N.R.K.), Boston University School of Medicine; the Department of Health Policy and Management (D.R.B., M.M.), Boston University School of Public Health; and the VA Boston Healthcare System (N.R.K.), Boston, Mass.

Correspondence to Adam J. Rose, MD, MSc, Center for Health Quality, Outcomes, and Economic Research, 200 Springs Road, Building 70, Bedford, MA 01730. E-mail adamrose{at}bu.edu

Received November 25, 2008; accepted April 21, 2009.

Background— Greater treatment intensification (TI) improves hypertension control. However, we do not know the ideal way to measure TI for research and quality improvement efforts. We compared the ability of different TI measures to predict blood pressure (BP) control.

Methods and Results— We enrolled 819 hypertensive outpatients from an urban academic hospital. Each patient was assigned 3 scores to characterize TI. The any/none score divides patients into those who had any therapy increases during the study versus none. The norm-based method models the chance of a medication increase at each visit, then scores each patient based on whether they received more or fewer medication increases than predicted. The standard-based method is similar to the norm-based method but expects a medication increase whenever the blood pressure is uncontrolled. We compared the ability of these scores to predict the final systolic blood pressure (SBP). The any/none score showed a paradoxical result: any therapy increase was associated with SBP 4.6 mm Hg higher than no increase (P<0.001). The norm-based method score did not predict SBP in a linear fashion (P=0.18); further investigation revealed a U-shaped relationship between the norm-based method score and SBP. However, the standard-based method score was a strong linear predictor of SBP (2.1 mm Hg lower for each additional therapy increase per 10 visits, P<0.001). Similarly, the standard-based method predicted dichotomized blood pressure control, as measured by SBP <140 mm Hg (odds ratio, 1.30; P<0.001).

Conclusions— Our results suggest that standard-based method is the preferred measure of treatment intensity for hypertension care.

Key Words: hypertension • chronic disease • research • quality of health care • ambulatory care

The online-only Data Supplement can be found at http://circoutcomes.ahajournals.org/cgi/content/full/10.1161/CIRCOUTCOMES.108.838649/DC1.