[Skip to Content]
Access to paid content on this site is currently suspended due to excessive activity being detected from your IP address 34.204.193.85. Please contact the publisher to request reinstatement.
[Skip to Content Landing]
Original Investigation
February 13, 2006

The Implications of Choice: Prescribing Generic or Preferred Pharmaceuticals Improves Medication Adherence for Chronic Conditions

Author Affiliations

Author Affiliations: Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women's Hospital and Harvard Medical School, Boston, Mass (Drs Shrank and Avorn); VA Greater Los Angeles Healthcare System, Los Angeles, Calif (Drs Hoang, Glassman, and Asch); Department of Medicine, The David Geffen School of Medicine at UCLA, Los Angeles (Drs Ettner, Glassman, and Asch); RAND Health, Santa Monica, Calif (Drs Glassman and Asch); Department of Pharmacy, University of Colorado Health Sciences Center, Denver (Dr Nair); Anthem Blue Cross and Blue Shield, Denver (Mss DeLapp and Dirstine); and Anthem Prescription Management, Denver (Mss DeLapp and Dirstine).

Arch Intern Med. 2006;166(3):332-337. doi:10.1001/archinte.166.3.332
Abstract

Background  A large proportion of Americans are enrolled in 3-tier pharmacy benefit plans. We studied whether patients enrolled in such plans who receive generic or preferred brand-name agents when initiating chronic therapy were more adherent to treatment than those who received nonpreferred brand-name medications.

Methods  We analyzed pharmacy claims filled between October 1, 2001, and October 1, 2003, from a large health plan for 6 classes of chronic medications: 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, calcium channel blockers, oral contraceptives, orally inhaled corticosteroids, angiotensin receptor blockers, and angiotensin-converting enzyme inhibitors. We measured adherence as the proportion of days covered (PDC) in each drug class during the first year of therapy. We evaluated how the formulary status of the initial prescription (generic, preferred, or nonpreferred) influenced PDC and adequate adherence, defined as PDC greater than 80%, over the subsequent year.

Results  A total of 7532 new prescriptions were filled in 1 of the classes evaluated: 1747 (23.2%) for nonpreferred medications, 4376 (58.1%) for preferred drugs, and 1409 (18.7%) for generic drugs. After controlling for patient sociodemographic characteristics and drug class, PDC was 12.6% greater for patients initiated on generic medications vs nonpreferred medications (58.8% vs 52.2%; P<.001). The PDC was 8.8% greater for patients initiated on preferred vs nonpreferred medications (56.8% vs 52.2%; P<.001). Patients initiated on generic and preferred medications had 62% and 30% greater odds, respectively, of achieving adequate adherence compared with those who received nonpreferred medications.

Conclusion  In 3-tier pharmacy benefit plans, prescribing generic or preferred medications within a therapeutic class is associated with improvements in adherence to therapy.

×