Costs and utilization associated with pharmaceutical adherence in a diabetic population.

OBJECTIVE: To determine whether adherence with pharmaceutical therapy affects well being and total costs associated with diabetes treatment. STUDY
DESIGN: Retrospective cohort design using insurance claims in an open access, nonmanaged care setting. PATIENTS AND METHODS: Patients with diabetes were under age 65 years, continuously enrolled with medical and drug eligibility, and identified by using methodology based on the Health Employer Data and Information Set. Patients were identified in 1998. The level of adherence to drugs used for diabetes, utilization, and medical costs were measured in 1999. Regression analyses statistically controlled for age, sex, illness severity, and product line.
RESULTS: Of the 57,687 patients identified with diabetes, 55% were male and 90% were age 40 years or older. Study members taking a prescription medicine for diabetes were significantly older and marginally sicker than those not taking a prescription medicine for diabetes. Patients without diabetic drug claims had the lowest medical costs, whereas younger patients and female patients had higher costs and utilization. A threshold effect was observed, where a target level of adherence was needed before medical care costs were reduced. Increased pharmaceutical adherence was associated with fewer emergency department visits and inpatient admissions. Increased medication adherence was associated with decreased medical care costs. Increased medication adherence was not associated with decreased overall healthcare costs because medication costs offset medical care cost savings.
CONCLUSION: Increased adherence with pharmaceutical therapy was associated with decreased use of medical care services, suggesting improved disease control and well being, but not with lower costs.