title: 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 > or = 3 antihypertensives (including a diuretic), occurred in 15% to 18% of patients in prospective cohort trials.
  
  
  OBJECTIVE
  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 > or = 140/90 mm Hg (>130/80 mm Hg for those with diabetes mellitus or kidney disease). Patients treated with > or = 3 agents (including a thiazide) who had > or = 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 > or = 18 years, 21,460 (72.8%) had > or = 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 mellitus (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.
authors.affiliation: Pharmacotherapy Outcomes Research Center, University of Utah, Salt Lake City, Utah 84108, USA. Carrie.mcadam-marx@pharm.utah.edu
authors.forename: Carrie
authors.initials: C
authors.lastname: McAdam-Marx
authors.forename: Xiangyang
authors.initials: X
authors.lastname: Ye
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Sung
authors.forename: Diana I
authors.initials: DI
authors.lastname: Brixner
authors.forename: Kristijan H
authors.initials: KH
authors.lastname: Kahler
mesh_terms: D000368:Aged; D000553:Ambulatory Care / Q000379:methods / Q000706:statistics & numerical data*; D000554:Ambulatory Care Facilities / Q000706:statistics & numerical data; D000959:Antihypertensive Agents / Q000627:therapeutic use; D001794:Blood Pressure / Q000187:drug effects; D015992:Body Mass Index; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004232:Diuretics / Q000627:therapeutic use; D004351:Drug Resistance; D004359:Drug Therapy, Combination; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006852:Hydrochlorothiazide / Q000627:therapeutic use; D006973:Hypertension / Q000188:drug therapy / Q000453:epidemiology*; D008297:Male; D016347:Medical Records Systems, Computerized; D008875:Middle Aged; D010865:Pilot Projects; D015995:Prevalence; D012189:Retrospective Studies
chemical_list: D000959:Antihypertensive Agents; D004232:Diuretics; D006852:Hydrochlorothiazide