DESIGN: Retrospective medical chart review using a standardized data collection form. Patients who had received a calcium channel blocker prescription for the month of May 1997 were selected randomly from the insured population of CIGNA HealthCare of Florida. Chart review and analysis were conducted by experienced clinical monitors from Total Therapeutic Management, Inc., a pharmacy utilization and disease management company.

SETTING: CIGNA HealthCare of Florida, a mixed model, multi-market health maintenance organization in Florida.

PATIENTS: The random sample consisted of 320 patients of the 4,155 patients who received a calcium channel blocker during May 1997.

MAIN OUTCOME: Appropriateness of calcium channel blocker therapy for hypertension based on patient demographics, comorbid disease state, and blood pressure control. Appropriateness of therapy was determined through CIGNA HealthCare of Florida's expert panel, made up of the CIGNA HealthCare of Florida Pharmacy and Therapeutics Committee, medical directors, and Cardiology Quality Council. This panel listed clinical criteria prior to the study in which patients treated with calcium channel blockers might benefit from a change to or an addition of an ACE inhibitor.

RESULTS: In the study population, based on the clinical criteria developed by the expert panel, researchers found that 46% of the patients taking calcium channel blockers could benefit from a change in antihypertensive therapy to an ACE inhibitor. Another 23% of the patients already were taking an ACE inhibitor along with their calcium channel blocker, while 31% of the patients would not benefit from a change in therapy to an ACE inhibitor.

CONCLUSION: Calcium channel blocker therapy is a highly utilized class for hypertension within managed care organizations. This study showed that many hypertensive patients with concomitant comorbid diseases might be more appropriately treated with ACE inhibitors.

KEYWORDS: Calcium channel blocker, Angiotensin converting enzyme inhibitor, Comorbid disease state, Managed care, Outcomes assessment

J Managed Care Pharm 1999: 537-540

Over the last few years, a more rational basis for selecting initial antihypertensive therapy has been recommended-an approach that more closely fits a patient's individualized needs and demographics.³ Individualized therapy involves three considerations: the patient's race, the patient's age, and the patient's concomitant conditions.

Calcium channel blockers comprise one of the most highly utilized drug classes within a managed care organization (MCO).⁴ Whether these drugs are used for hypertension, angina, or a combination of both, the appropriateness of drug selection should be evaluated. Other studies have presented evidence that raises questions about the safety of some calcium channel blockers, particularly, but not only, short-acting dihydropyridines such as nifedipine.⁵ In patients with hypertension and angina, a calcium channel blocker is drug of choice.⁶ For patients with hypertension and concomitant congestive heart failure or diabetes, ACE inhibitors represent a more appropriate clinical choice based on their cardioprotective and renal perservation functions.⁷ In addition, data are available suggesting that ACE inhibitors can improve endothelial dysfunction.⁸ This improvement in endothelium may help to explain the beneficial effects of ACE inhibitors in reducing the number of cardiac ischemic events and the need for revascularization.^9,10

METHODS
This study retrospectively examined the medical charts of patients who received calcium channel blocking agents during the month of May 1997 at CIGNA HealthCare of Florida. Patients were selected randomly from the insured population using a random number generator. To conduct the random selection, the pharmacy director provided an electronic file that contained calcium channel blocker utilization data for the month of May 1997.

Clinical pharmacists collected data from patient medical records using a data collection tool designed to capture all information needed to evaluated outcomes following calcium channel blocker use for hypertension. Major data collection variables included demographics, (age, sex, weight, race); chief complaint; diagnosis; patient comorbid disease states, (congestive heart failure, diabetes, coronary artery disease, chronic obstructive pulmonary disease); concomitant medications; and clinical outcomes, (blood pressure control, coronary artery disease symptom relief, congestive heart failure symptom relief).

The outcome measures included appropriate use of calcium channel blockers based on the clinical criteria developed by CIGNA HealthCare of Florida. Table 1 displays appropriate use criteria for calcium channel blockers, ACE inhibitors, and angio-tensin II receptor blockers. Based on these clinical criteria, the study determined if patients were appropriately using calcium channel blockers or would benefit from a switch to an ACE inhibitor.

RESULTS
Of the 4,155 CIGNA HealthCare of Florida patients who were prescribed calcium channel blockers in the month of May 1997, 517 patients were selected for medical chart review. Of the 517 charts that were selected, 320 charts were appropriate for evaluation. Of the 320 patient charts reviewed, 46% of the patient were females and 54% were male. Patient ages ranged from 29-89 years old, with a mean age of 54.17. Most patients (272) evaluated were in the age range of 41-70 years, accounting for 85% of the study population. When treating hypertension, the patient's race must be considered in drug selection. Of the 320 charts reviewed, only 137 charts had a documented race for the patient. Of these patients, 64% were Caucasian, 24% were African-American, and 12% were Hispanic.

The most prevalent disease states found concomitantly with hypertension were dyslipidemia, obesity, and diabetes. In the overall population, 110 (36.18%) patients had dyslipide-mia, 58 (19.08%) were obese, and 52 (17.11%) had diabetes along with hypertension (see Figure 1).

One hundred and ninety patients were taking concomitant antihypertensive drugs along with calcium channel blockers. In the overall study population, 70 (21.88%) were on ACE inhibitors, 62 (19.38%) were taking thiazide diuretics, and 56 (17.5%) were on beta-adrenergic blockers. In addition, 9% of patients also took alpha blockers, 7% were taking loop diuretics, and 6% were using a combination of diuretics.

Drug use was evaluated by the patient's comorbid disease. One of the most important findings was that of the 52 patients with existing diabetes, only 18 (35%) were on an ACE inhibitor.

Clinical criteria for hypertensive patients that would benefit from a change in therapy to an ACE inhibitor were developed prior to initiation of the study. Based on these clinical criteria, the study found that 46% of patients taking calcium channel blockers would benefit from a change in antihypertensive therapy to an ACE inhibitor. Another 23% of patients were already taking an ACE inhibitor along with their calcium channel blocker. Because 31% of patients had a history of prior failure on an ACE inhibitor, or had concomitant angina or arrhythmia with their hypertension, these patients would not benefit from a change to an ACE inhibitor.

The calcium channel blocker with the higher percentage of patients that would benefit from a change to an ACE inhibitor was extended-release nifedipine at 55%. The calcium channel blockers in which the patient would least benefit from a change to an ACE inhibitor are verapamil extended release (40%) and felodipine (40%) (see Figure 2).

DISCUSSION
The appropriate-use program of calcium channel blockers and ACE inhibitors at CIGNA HealthCare of Florida revealed significant findings that can be used as a basis for disease management-related continuous quality improvement programs.

One important criteria evaluated in this study was patient comorbid disease states. When selecting antihypertensive therapy, the consideration of the patient's existing comorbid states is critical.³ The appropriate use criteria were developed based on patient comorbid disease states, as well as blood pressure control. Of the patients in the study, 52 had diabetes; of these patients, only 18 were already on an ACE inhibitor. A recent study comparing diabetic patients with hypertension being treated with either enalapril or nisoldipine evaluated the use of these agents in patients with hypertension and other co-morbid disease states. The authors concluded that an ACE inhibitor appears to be the preferred antihypertensive agent, rather than a dihydropyridine calcium channel blocker, for the prevention of cardiovascular complications, specifically myocardial infarction, in patients with noninsulin dependent diabetes mellitus.⁵

One of the main objectives of this study was to identify patients who could benefit from a change to ACE inhibitor therapy. Based on these criteria, 46% of patients taking calcium channel blockers could benefit from a change in antihypertensive therapy to an ACE inhibitor. If patients' hypertension was controlled to <140/90 mm Hg on their current therapy, we did not consider that they would benefit from a change in therapy. If a patient had diabetes, congestive heart failure or left ventricular hypertrophy, then this patient might be able to benefit from an ACE inhibitor. The available literature strongly supports superiority of ACE inhibitors in hypertension/diabetes or hypertension/congestive heart failure.^5,6

Implementation of a disease management process helps ensure patients are receiving the maximum benefit from prescribed drug therapy and other treatment. This study indicates that physician utilization of antihypertensives can be improved by using appropriate agents in the appropriate patient types.

  References