We evaluated approximately 5.6 million prescriptions that were delivered to retail or mail-order pharmacies and adjudicated through Caremark during the 1-month period. These prescriptions were written for 2,047,124 patients by 315,379 specialist physicians, 126,430 generalists, and 39,128 non-physician prescribers (eg, nurse practitioners). Patients and their insurance plans, respectively, paid an average of $17.90 and $26.67 for generic medications, $49.50 and $158.25 for single-source brands, and $44.50 and $135.26 for multi-source brands.

Of the prescriptions we evaluated, 151,670 (2.7%) were designated as dispense as written by physicians and 112,243 (2.0%) were designated as dispense as written by patients. A majority of prescriptions designated as dispense as written by physicians were single-source brand products for which no generic alternatives were available. Most patient-assigned dispense as written prescriptions were for multi-source brands, which could have otherwise been substituted at the pharmacy without contacting the physician. Patient requests for dispense as written took place almost exclusively at retail pharmacies, whereas approximately one third of physician requests were filled at mail-order pharmacies.

Among multi-source brands used to treat chronic conditions (maintenance medications), patients failed to fill prescriptions more frequently when either patients or physicians requested dispense as written, compared with prescriptions with no dispense as written designation.

In multivariate analyses, older physicians were more likely to request dispense as written than younger ones, and patients age 55 to 74 years were most likely to receive physician dispense as written prescriptions. The odds of requesting dispense as written was 78.5% greater for specialists than generalists (P<;.001). Compared with rates of dispense as written request for oral antidiabetics (the referent class), a dispense as written was more likely to be written for anticonvulsants (odds ratio [OR] 2.2), estrogens (OR 2.2), migraine treatments (OR 2.4), thyroid medications (OR 9.8), and anticoagulants (OR 3.9). Physician dispense as written was more common in the northeast section of the country (OR 1.76 vs west, P<;.001) and when submitted to mail-order pharmacies.

The likelihood of patient dispense as written requests also varied by therapeutic class and region. Compared with oral antidiabetics, patient dispense as written requests were more common for ulcer agents (OR 6.1), hypnotics (OR 4.3), migraine medications (OR 14.4), contraceptives (OR 3.7), thyroid medications (OR 16.5), estrogens (OR 3.6), anticonvulsants (OR 4.8), anticoagulants (OR 4.5), and analgesics (OR 4.5). Patient dispense as written was requested most frequently in the west; there were 32.4% greater odds for having a patient-assigned dispense as written in the west than in the northeast (P<;.001). Dispense as written was most commonly requested by patients who were 55 to 74 years of age, for maintenance medications, and at retail pharmacies.