Utilization patterns and medication adherence in patients with type 2 diabetes: variations based on type of pharmacy (chain vs independent)

Res Social Adm Pharm. 2007 Dec;3(4):378-91. doi: 10.1016/j.sapharm.2006.11.002.


Background: Independent pharmacies have demonstrated a positive effect on patient satisfaction, dispensing errors, and patient consultation/counseling. However, there is a lack of studies demonstrating whether these benefits translate into outcomes such as medication adherence.

Objective: To estimate the variations in utilization patterns and adherence to oral hypoglycemic agents (OHAs) based on type of pharmacy (chain/independent).

Methods: A retrospective cohort design was used to meet the study objective. Newly diagnosed type 2 diabetes patients during a 4-year period were identified from a Medicaid claims database. The provider of the index prescription was classified as a chain or independent pharmacy. Utilization patterns (switching, augmentation, discontinuation, nonmodification) and adherence to OHAs (medication possession ratios) were computed for a 12-month follow-up period from the date of the index OHA prescription. A multivariate framework was used to estimate the effect of type of pharmacy on utilization patterns and adherence after controlling for confounding variables.

Results: A total of 2696 newly diagnosed type 2 diabetes patients were identified (independent pharmacy=987; chain pharmacy=1709). Utilization patterns were significantly different between the 2 groups with patients filling their prescription at a chain pharmacy 1.3 times more likely to augment therapy as compared to patients filling prescriptions at an independent pharmacy (P=.035). Independent sample t tests indicated that adherence to OHAs (Mean+/-SD) was significantly higher for patients filling their prescriptions at a independent pharmacy (0.90+/-0.13) as compared to those filling prescriptions at a chain pharmacy (0.88+/-0.13, P=.01). Results of a semi-log Ordinary Least Squares model also indicated that controlling for covariates, patients filling prescriptions at an independent pharmacy had significantly higher adherence to OHAs as compared to those filling prescriptions at a chain pharmacy (P=.02).

Conclusion: Results of the study indicated that patients with type 2 diabetes who received their OHAs from an independent pharmacy have slightly higher adherence rates as compared to those filling their OHA prescriptions at a chain pharmacy.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Age Factors
  • Cohort Studies
  • Diabetes Mellitus, Type 2 / drug therapy*
  • Drug Monitoring / methods*
  • Drug Prescriptions
  • Drug Utilization
  • Female
  • Humans
  • Hypoglycemic Agents / therapeutic use
  • Logistic Models
  • Male
  • Patient Compliance*
  • Pharmacies / organization & administration*
  • Population
  • Retrospective Studies
  • Treatment Outcome


  • Hypoglycemic Agents