Resistant hypertension in a tertiary care clinic.

Study Objective: --To determine the prevalence of resistant hypertension in a tertiary care facility, the frequency of its various causes, and the results of treatment.

Design: --Review of clinic records of all patients seen for the first time between January 1, 1986, and December 31, 1988.

Methods: --Patients meeting criteria for resistant hypertension were examined for appropriateness of their medical regimen, presence of secondary causes of hypertension, noncompliance, interfering substances, drug interactions, office resistance (elevated blood pressure in the office only while receiving treatment), and other potential causes of resistance.

Results: --Of the 436 charts reviewed, 91 were those of patients who met criteria for resistant hypertension and were seen more than once. The most common cause was a suboptimal medical regimen (39 patients), followed by medication intolerance (13 patients), previously undiagnosed secondary hypertension (10 patients), noncompliance (nine patients), psychiatric causes (seven patients), office resistance (two patients), an interfering substance (two patients), and drug interaction (one patient). Blood pressure control, defined as diastolic blood pressure of 90 mm Hg or less and systolic blood pressure of 140 mm Hg or less for patients aged 50 years or less (less than or equal to 150 mm Hg for those aged 51 to 60 years and less than or equal to 160 mm Hg for those aged greater than 60 years), was achieved in 48 (53%) of those 91 patients. Another 10 had significant improvement in their blood pressure (greater than or equal to 15% decrease in diastolic blood pressure). Of patients whose blood pressure was controlled after they had been on a suboptimal regimen, the two most frequently used therapeutic strategies were to add (50%) or modify (24%) diuretic therapy or to add (50%) or increase the dose of (12%) a newer drug, either a calcium entry blocker or angiotensin-converting enzyme inhibitor.

Conclusion: --We conclude that resistant hypertension is common in a tertiary care facility and that a suboptimal regimen is the most common reason. Furthermore, in the majority of these patients, the elevated blood pressures can be controlled or significantly improved.