April 27, 2009

Pharmacoutilization of antihypertensive drugs: a model of analysis

Q: What is the clinical evidence from this study?

Study design: Observational. Population: Hypertension (n=4614). Intervention: Antihypertensive drugs (amlodipine, atenolol, fosinopril, indapamide, or losartan). Primary outcome: Treatment discontinuation.

Key Result

Among patients receiving a first prescription for antihypertensive drugs, 65.1% discontinued treatment, which represented 31.1% of total expenditures.

Study Design

Type

Observational (n=4,614)

Structured PICO

What are the patterns of continuation, discontinuation, switching, and costs associated with first prescriptions of antihypertensive drugs?

Population

4,614 subjects receiving a first prescription for amlodipine, atenolol, fosinopril, indapamide, or losartan

Intervention

First prescription of antihypertensive drugs (amlodipine, atenolol, fosinopril, indapamide, or losartan)

Outcome

Percentage of patients continuing, discontinuing, and switching the initial treatment, duration of treatment, doses used, and total costs

A retrospective analysis of antihypertensive drug utilization reveals high rates of treatment discontinuation and sub-therapeutic dosing, highlighting inefficiencies in resource usage.

Abstract

OBJECTIVES: To identify clinical and economic indicators of pharmacoutilization of antihypertensive drugs. PATIENTS AND METHODS: 4614 subjects receiving a first prescription for amlodipine, atenolol, fosinopril, indapamide, or losartan were included in the study. All prescriptions filled during the study period from January 1, 1997 to December 31, 1998 were considered. A retrospective analysis was carried out on information recorded in the drug database. The percentage of patients continuing, discontinuing, and switching the initial treatment, duration of treatment, and doses used were calculated together with total costs. RESULTS: A large proportion of patients (65.1%) discontinued the treatment. From the analysis of the mean daily dose taken by patients who continued the treatment, it was found that many subjects took a drug dosage which was below the therapeutic dose range, whereas the administration of doses above the therapeutic range occurred only occasionally. Continuation of treatment accounted for 48.1% of total costs, switching accounted for 20.8%, and discontinuation represented 31.1% of total expenditures. CONCLUSIONS: With adequate markers, helpful data can be collected for monitoring the quality of antihypertensive drug prescriptions and the rational usage of resources in the general practice setting.

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