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

Abstract

BACKGROUND:Little is known about first-fill adherence rates for diabetic medications and factors associated with non-fill.OBJECTIVE: 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. DESIGN:Retrospective, cohort study linking electronic health records and pharmacy claims. PARTICIPANTS: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. MEASUREMENTS:The primary outcome of interest was naïve prescription filled by the patient within 30 days of the prescription order date. RESULTS: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 firstfill 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.CONCLUSIONS: 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.

A Randomized Telephone Intervention Trial to Reduce Primary Medication Nonadherence

“…Two studies of large populations of patients in different clinical settings found PMN rates over 20%, 16,17 and studies of PMN for patients in the Geisinger system found PMN rates of 15%-17% among patients prescribed antihypertensive and oral diabetes medications. 20,21 Our considerably lower PMN rates are similar to those seen in recent reports from other integrated health care settings, [22][23][24] suggesting perhaps the structure of the health system or the use of e-prescribing was a factor in first-fill rates. However, a key difference between these studies and ours is the use of primarily in-network pharmacies versus our use of an independent pharmacy chain.…”

“…Unexpectedly, 94% of patients picked up their index prescription before becoming eligible for the study (4,532/4,822), a much lower rate of PMN than found in prior observational studies either in the Geisinger system or elsewhere. 20,21 The low rate of PMN resulted in much slower than anticipated addition of patients to the study population, with final total enrollment of 290 patients rather than the prespecified target of 298. …”

“…18 Studies in integrated health care systems have found lower rates of PMN (15%-17% for antihypertensives and antidiabetic medications), but the scope of the problem is substantial even in these settings. [19][20][21][22][23][24] • Primary medication nonadherence (PMN) occurs for 15%-30% of prescriptions, so that many patients never start taking medications prescribed to treat chronic diseases.…”

Primary Non-adherence to Prescribed Medications

“…At least two other recent studies of adherence to new prescriptions for diabetes and hypertension among patients treated in a single health system found non-adherence rates similar to those seen in our study. 2,3 As with the comparison between our findings and those of Karter et al, it is difficult to be certain whether these findings reflect some characteristics unique to the study setting as opposed to more universal behaviors around prescription filling. We agree that more such studies will be needed, both to improve the methods used for identifying primary non-adherence and to develop more robust estimates of the prevalence of this phenomenon in a wide variety of real-world practice settings.…”

Store and Prescription Characteristics Associated with Primary Medication Nonadherence

“…9 Other studies have found similarly high rates of PMN. 10,11 Shin et al (2012) found an overall PMN rate of 9.8% in a managed care organization. 12 The investigators identified patient, prescriber, and prescription characteristics associated with PMN for medications used to treat acute and chronic conditions and found differences.…”