A controlled letter intervention to change prescribing behavior: results of a dual-targeted approach

To determine the effectiveness of a drug utilization review (DUR) letter intervention sent only to physicians, sent only to pharmacists, or sent to both physicians and pharmacists in changing physician prescribing behavior for dipyridamole.

A Wisconsin Medicaid prescription drug database for data from March 1991 through May 1992 related to both long-term care and ambulatory patient settings.

The effects of a DUR letter intervention were tested using a field study, pre-post, nonequivalent control group, quasi-experimental design. The effects of the letter intervention in terms of dipyridamole expenditures (dollars reimbursed to pharmacies by Medicaid), expenditures for related drugs (aspirin, ticlopidine, sulfinpyrazone) and numbers of patients for whom dipyridamole was discontinued were examined across three experimental groups and a control group.

Dipyridamole expenditures for each study patient during a six-month preintervention and six-month postintervention period were collected from Medicaid prescription drug claims. Patients who had zero dipyridamole expenditures throughout the six-month postintervention period were classified as having had dipyridamole discontinued.

Letters sent to both physicians and pharmacists resulted in a greater percentage of patients discontinuing dipyridamole relative to controls and statistically significant differences in postintervention dipyridamole expenditures relative to controls in both the long-term care and ambulatory patient populations.

Interventions that focus on another person in the drug use process in addition to the physician may have greater effects on a change in the prescribing of a targeted drug than letters to physicians alone.