Journal of General Internal Medicine

, Volume 24, Issue 2, pp 233–237

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


  1. 1.
    Haynes TB, Taylor DW, Sackett DL. Compliance in Health Care. Baltimore, MD: Johns Hopkins University Press; 1979.Google Scholar
  2. 2.
    Balkrishnan R. The importance of medication adherence in improving chronic-disease related outcomes: what we know and what we need to further know. Med Care. 2005;43(6):517–20.CrossRefPubMedGoogle Scholar
  3. 3.
    Mojtabai R, Olfson M. Medication costs, adherence, and health outcomes among Medicare beneficiaries. Health Aff (Millwood). 2003;22(4)220–9.CrossRefGoogle Scholar
  4. 4.
    McDonald HP, Garg AX, Haynes RB. Interventions to enhance patient adherence to medication prescriptions: scientific review. JAMA. 2002;288(22):2868–79.CrossRefPubMedGoogle Scholar
  5. 5.
    Charlson ME, Pompei P, Ales KL, MacKenzie CR. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis. 1987;40(5)373–83.CrossRefPubMedGoogle Scholar
  6. 6.
    Rothman KJ, Greenland S. Modern Epidemiology, 2nd edn. New York: Lippincott Williams & Wilkins; 1998.Google Scholar
  7. 7.
    Pladevall M, Williams LK, Potts LA, Divine G, Xi H, Lafata JE. Clinical outcomes and adherence to medications measured by claims data in patients with diabetes. Diab Care. 2004;27(12):2800–5.CrossRefGoogle Scholar
  8. 8.
    Schetman JM, Nadkarni MM, Voss JD. The association between diabetes metabolic control and drug adherence in an indigent population. Diab Care. 2002;25(6):1015–21.CrossRefGoogle Scholar
  9. 9.
    Kienle GS, Kiene H. The powerful placebo effect: Fact or fiction? J Clin Epi. 1997;50(12):1311–8.CrossRefGoogle Scholar
  10. 10.
    Johnson RE, Goodman MJ, Hornbrook MC, Eldredge MB. The effect of increased prescription drug cost-sharing on medical care utilization and expenses of elderly health maintenance organization members. Med Care. 1997;35:1119–31.CrossRefPubMedGoogle Scholar
  11. 11.
    Babazono A, Tsuda T, Yamamoto E, Mino Y, Une H, Hillman AL. Effects of an increase in patient copayments on medical service demands of the insured in Japan. Int J Technol Assess Health Care. 2003;19(3):465–75.CrossRefPubMedGoogle Scholar
  12. 12.
    Chernew M, Gibson TB, Yu-Isenberg K, Sokol MC, Rosen AB, Fendrick AM. Effects of increased patient cost sharing on socioeconomic disparities in health care. J Gen Int Med 2008;epub ahead of print.Google Scholar
  13. 13.
    DiMatteo MR. Variations in patients’ adherence to medical recommendations: a quantitative review of 50 years of research. Med Care. 2004;42(3):200–9.CrossRefPubMedGoogle Scholar
  14. 14.
    van Dulmen S, Sluijs E, van Dijk L, de Ridder D, Heerdink R, Bensing J. Patient adherence to medical treatment: A review of reviews. BMC Health Services Research. 2007;7(55).Google Scholar
  15. 15.
    Ho PM, Magid DJ, Shetterly SM, et al. Importance of therapy intensification and medication nonadherence for blood pressure control in patients with coronary disease. Arch Intern Med. 2008;168(3):271–6.CrossRefPubMedGoogle Scholar
  16. 16.
    Schmittdiel JA, Uratsu CS, Karter AJ, et al. Why don’t diabetes patients achieve recommended risk factor targets? Poor adherence versus lack of treatment intensification. J Gen Intern Med. 2008;23(5):588–94.CrossRefPubMedGoogle Scholar
  17. 17.
    American Diabetes Association. Diabetes statistics. Available at Accessed on May 7, 2008.

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

Personalised recommendations