Predictors of First-Fill Adherence for Patients With Hypertension

Abstract

BACKGROUND Between the promise of evidence-based medicine and the reality of inadequate patient outcomes lies patient adherence. Studies of prescription adherence have been hampered by methodologic problems. Most rely on patient self-report of adherence or cross-sectional data of plan-wide prescription fills to estimate patient-level adherence. METHODS We conducted a retrospective cohort study and linked individual patient data for incident prescriptions for antihypertensive medications from electronic health records (EHRs) to claims data obtained from the patient's insurance plan. Clinical data were obtained from the Geisinger Clinic, a 41 site group practice serving central and northeastern Pennsylvania with an EHR in use since 2001. Adherence was defined as a prescription claim generated for the first-fill prescription within 30 days of the prescribing date. RESULTS Of the 3,240 patients written a new, first-time prescription for an antihypertensive medication, 2,685 (83%) generated a corresponding claim within 30 days. Sex, age, therapeutic class, number of other medications prescribed within 10 days of the antihypertensive prescription, number of refills, co-pay, comorbidity score, baseline blood pressure (BP), and change in BP were significantly associated with first-fill rates (P < 0.05). CONCLUSIONS Patients who are older, female, have multiple comorbidities, and/or have relatively lower BPs may be less likely to fill a first prescription for antihypertensive medications and may be potential candidates for interventions to improve adherence to first-fill prescriptions.

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.…”

Pharmacy-based Interventions to Reduce Primary Medication Nonadherence to Cardiovascular Medications

“…13,14 Studies in closed health care systems have found slightly lower rates of PMN (15%-26%), although the problem is still substantial. [15][16][17] Once PMN can be identified and measured, the challenge is to identify interventions specifically targeting PMN. Systematic reviews of the adherence literature indicate that community pharmacists can play an important role.…”