Abstract 246: Challenges in Defining Resistant Hypertension: Prevalence Among Hypertensive Outpatients Varies With Inclusion of Diuretic Use and Medication Dosing

Background: Resistant hypertension (RH) is defined as BP above goal despite the use of 3 antihypertensive agents of different classes, or BP controlled on 4 agents, ideally maximally dosed and including a diuretic. RH studies have used varying interpretations of this definition, with prevalence estimates ranging from 3% to 30%. This study characterizes RH when different definitions are used in the same population. METHODS: We calculated the prevalence of RH among consecutive hypertensive outpatients presenting to an academic cardiology clinic over 6 months using 4 increasingly stringent definitions of RH. These included 1) SBP>140 (130 if DM or CKD) on three medications or controlled on four medications regardless of dosage; 2) Definition 1 including a diuretic; 3) SBP>140 (130 if DM or CKD) on three maximally-dosed medications (per JNC-7) or controlled on four medications, at least three which are maximally dosed; and 4) Definition 3 including a diuretic. We compared demographic and clinical characteristics of patients with and without RH using chi-square and t tests. Results: Among 1761 hypertensive outpatients, 46 (2.6%), 374 (21.2%), 602 (34.2%), and 739 (42.6%) were using 0, 1, 2, and ≥3 medications, respectively; 856 (47.6%) were using a diuretic-containing regimen. Overall, 500 patients (28.4%) had RH by Definition 1, which decreased to 402 patients (22.8%) using Definition 2 which required a diuretic. However, with inclusion of medication dosage, the number of patients with RH decreased to 29 (1.7%) using Definition 3, and 24 (1.4%) using Definition 4. RH using Definition 1 was associated with African-American race, female sex, coronary disease, diabetes, congestive heart failure, stroke, and end-stage renal disease (p<0.05). Conclusion: RH represents a small proportion of the overall hypertensive population when a strict definition of RH including maximal medication dosing and/or the presence of a diuretic is applied. These findings suggest that some patients with RH by more inclusive definitions may benefit from optimization of antihypertensive therapy. Consistent definitions of RH should be applied in the future to ensure that RH is adequately identified and so RH treatment interventions and pathophysiology may be consistently compared.