Abstract
Background: Much of the distance between the promise of evidence-based medicine and reality of improved patient outcomes can be attributed to problems in the ‘last mile,’ or patient adherence – the extent to which a person’s behavior coincides with medical or health advice. 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. We used a unique combination of electronic health record (EHR) data from clinics and prescription claims data to understand first-fill rates for hypertension and factors associated with first-fill behavior.
Methods: We conducted a retrospective cohort study and linked individual patient data for new (i.e., first-time) prescriptions of medications for hypertension from EHR, with claims data obtained from an insurance plan. EHR data were obtained from the Geisinger Clinic, a large group practice serving a 31-county area of central and northeastern Pennsylvania. The Clinic includes 41 community practice sites with primary and multi-specialty care, all of which have used an EHR since 2001. Adherence was defined as a claim generated for the first-fill prescription within 30 days of the index date.
Results: Of 3240 patients written a new, first-time prescription for any antihypertensive medication, 2685 (83%) generated a corresponding claim within 30 days. Gender, age, therapeutic class, number of medications prescribed within 10 days of prescription, number of refills, co-pay, comorbidity score, baseline systolic blood pressure, baseline diastolic blood pressure, change in systolic blood pressure, and change in diastolic pressure were significantly associated with first-fill rates (P<0.05). Race, number of hypertension medications ordered, number of office visits prior to prescription, post-systolic blood pressure, and post-diastolic blood pressure had no association.
Conclusions: The data reveal characteristics of patients who are less likely to adhere to treatment for hypertension. Patients who are older, female, have comorbidities, and/or have relatively lower blood pressures may be less likely to adhere to treatment for hypertension. Patients with these characteristics may be potential candidates for interventions to improve adherence.
- Received September 11, 2008.
