Background: Effective hypertension management often necessitates patients' adherence to the blood pressure (BP)-lowering medication regimen they are prescribed. Patients' adherence to that regimen can be affected by prescription- and payment-related factors that are typically controlled by prescribers, filling pharmacies, pharmacy benefit managers, and/or patients' health insurance plans. This study describes patterns and changes from 2009 to 2014 in factors that the literature reports are associated with increased adherence to BP-lowering medication.
Methods and findings: We use a robust source of United States prescription sales data-IMS Health's National Prescription Audit-to describe BP-lowering medication fill counts and spending in 2009 compared with 2014. Moreover, we describe patterns and changes in adherence-promoting factors across age groups, payment sources, and medication classes. From 2009 to 2014, the BP-lowering medication prescription fill count increased from 613.7 million to 653.0 million. Encouraging changes in adherence-promoting factors included: the share of generic fills increased from 82.5% to 95.0%; average days' supply per fill increased from 45.9 to 51.8 days; and average total (patient contribution) spending per years' supply decreased from $359 ($54) to $311 ($37). Possibly undesirable changes included: the percentage of fills for fixed-dose combinations decreased from 17.1% to 14.2% and acquired via mail order decreased from 10.7% to 8.2%. In 2014: 653.0 million fills occurred accounting for $28.81B in spending; adults aged 45-64 years had the highest percentage of fixed-dose combinations fills (16.9%); and fills with Medicaid as the payment source had the lowest average patient spending per fill ($1.19).
Conclusions: We identified both encouraging and possibly undesirable patterns and changes from 2009 to 2014 in factors that promote adherence to BP-lowering medications during this period. Continued tracking of these metrics using pharmacy sales data can help identify areas that can be addressed by clinical and policy interventions to improve adherence for medications commonly used to treat hypertension.