Results of a retrospective, observational pilot study using electronic medical records to assess the prevalence and characteristics of patients with resistant hypertension in an ambulatory care setting

Abstract

Background: Resistant hypertension, or failure to attain blood pressure (BP) goals while treated with ≥3 antihypertensives (including a diuretic), occurred in 15% to 18% of patients in prospective cohort trials. Objectives: The aims of this work were to identify the prevalence of resistant hypertension in an ambulatory care setting and to describe the characteristics of patients with resistant hypertension. Methods: Adults with hypertension were retrospectively identified in a US electronic medical record from November 1, 2002, through November 30, 2005. Antihypertensive treatment and BP values were assessed to identify those with BP ≥140/90 mm Hg (>130/80 mm Hg for those with diabetes mellitus or kidney disease). Patients treated with ≥3 agents (including a thiazide) who had ≥1 BP level above target were classified as having resistant hypertension. Baseline characteristics were compared between those with and those without resistant hypertension. Results: Of 29,474 study patients aged ≥18 years, 21,460 (72.8%) had ≥1 prescription order for an antihypertensive and 19,202 (65.1%) had a follow-up BP level above target. The analysis found that 2670 patients (9.1% overall or 12.4% of those who were treated) were classified as having resistant hypertension. Relative to those without resistant hypertension, a greater proportion of those with resistant hypertension were female (65.6% vs 60.5%), were older (66.2 vs 63.0 years), had a higher body mass index (31.6 vs 30.4 kg/m 2), had higher baseline BP levels (148/81 vs 138/80 mm Hg), and had higher rates of diabetes mel-litus (35.2% vs 20.1%) or kidney disease (4.9% vs 2.7%) than those without resistant hypertension (all comparisons, P < 0.001). Conclusions: This retrospective, observational pilot study of usual community practice supports the findings from prospective trials that resistant hypertension is an important clinical problem. More effective management is needed to enable patients with, or at risk for, resistant hypertension to achieve BP goals.