Journal of General Internal Medicine

, Volume 24, Issue 2, pp 233–237 | Cite as

Factors Associated with First-Fill Adherence Rates for Diabetic Medications: A Cohort Study

  • Nirav R. Shah
  • Annemarie G. Hirsch
  • Christopher Zacker
  • Scott Taylor
  • G. Craig Wood
  • Walter F. Stewart
Original Article



Little is known about first-fill adherence rates for diabetic medications and factors associated with non-fill.


To assess the proportion of patients who fill their initial prescription for a diabetes medication, understand characteristics associated with prescription first-fill rates, and examine the effect of first-fill rates on subsequent A1c levels.


Retrospective, cohort study linking electronic health records and pharmacy claims.


One thousand one hundred thirty-two patients over the age of 18 who sought care from the Geisinger Clinic, had Geisinger Health Plan pharmacy benefits, and were prescribed a diabetes medication for the first time between 2002 and 2006.


The primary outcome of interest was naïve prescription filled by the patient within 30 days of the prescription order date.


The overall first-fill adherence rate for antidiabetic drugs was 85%. Copays < $10 (OR 2.22, 95% CI 1.57–3.14) and baseline A1c > 9% (OR 2.63, 95% CI 1.35, 5.09) were associated with improved first-fill rates while sex, age, and co-morbidity score had no association. A1c levels decreased among both filling and non-filling patients though significantly greater reductions were observed among filling patients. Biguanides and sulfonylureas had higher first-fill rates than second-line oral agents or insulin.


First-fill rates for diabetes medication have room for improvement. Several factors that predict non-filling are readily identifiable and should be considered as possible targets for interventions.


diabetes medication adherence electronic health records pharmacoepidemiology 



Electronic Health Records


Geisinger Health Plan


Hemoglobin A1c



This work was supported by an unrestricted grant from Novartis Pharmaceuticals Corporation. Dr. Shah receives support from the Robert Wood Johnson Foundation as a Physician Faculty Scholar. None of the funders played any role in the design or conduct of the study, in the collection, analysis, or interpretation of the data, or in the preparation, review, or approval of the manuscript. Dr. Shah had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Nirav Shah has received unrestricted research grants from AstraZeneca, Berlex, GlaxoSmithKline, Merck, Novartis, Pfizer, and Roche; he has served as a consultant for Cerner Lifesciences and LifeTech Research. None of the authors have any financial interests in any of the devices or companies mentioned in this report, except that Chris Zacker works for the sponsor of this study.

Nirav Shah, Annemarie Hirsch, Scott Taylor, Chris Zacker, and Walter Stewart all played significant roles in the data collection, analysis, and write-up of the manuscript. Nirav Shah, Scott Taylor, and Walter Stewart conceived of the idea and obtained funding. Nirav Shah is the guarantor of the manuscript. Design and conduct of the study: Nirav Shah, Scott Taylor, Annemarie Hirsh, Walter Stewart, Chris Zacker; Collection, management, analysis: Nirav Shah, Craig Wood, Annemarie Hirsch; Interpretation of the data: Nirav Shah, Annemarie Hirsch, Scott Taylor, Walter Stewart, Craig Wood, Chris Zacker; Preparation, review, or approval of the manuscript: Nirav Shah, Annemarie Hirsch, Scott Taylor, Walter Stewart, Craig Wood.

Conflict of Interest Statement

Annemarie G. Hirsch, Scott Taylor, and G. Craig Wood report no conflicts of interest. Nirav R. Shah has held a consultancy position for Cerner LifeSciences within the past 3 years and has received grants from GlaxoSmithKline, Novartis, Roche Diagnostics, AstraZeneca, and Merck. Christopher Zacker has been employed with Novartis. Walter F. Stewart has received grants within the past 3 years from GlaxoSmithKline, Novartis, Roche Diagnostics, AstraZeneca, and Merck.


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Copyright information

© Society of General Internal Medicine 2008

Authors and Affiliations

  • Nirav R. Shah
    • 1
    • 2
    • 4
  • Annemarie G. Hirsch
    • 1
  • Christopher Zacker
    • 3
  • Scott Taylor
    • 1
  • G. Craig Wood
    • 1
  • Walter F. Stewart
    • 1
  1. 1.Center for Health ResearchGeisinger ClinicDanvilleUSA
  2. 2.Division of General Internal MedicineNew York University School of MedicineNew YorkUSA
  3. 3.Novartis Pharmaceuticals CorporationEast HanoverUSA
  4. 4.Center for Health ResearchGeisinger Health SystemDanvilleUSA

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