How does pharmacy benefit design affect patient's adherence to medicine?

Pharmacy benefit design has an important, direct influence on adherence to medicines. Higher copays and restrictive benefits lead to a reduction in use of medicines and can increase total medical costs in the long run.

A synthesis of the literature by researchers at RAND Health found a 2-6 percent decrease in prescription drug spending for every 10 percent increase in cost sharing (depending
on therapeutic class and patient outcomes). Researchers also found an unambiguous association between higher medication copays or cost-sharing and increased use of hospitalizations and emergency medical services for patients with congestive heart failure, lipid disorders,
diabetes, and schizophrenia.

Compared to seniors with uncapped prescription coverage, seniors with a $1,000 annual benefit cap under a Medicare+Choice plan were less likely to use medicines appropriately and experienced unfavorable clinical outcomes. Use of medicines to treat hypertension, high cholesterol, and diabetes was 15 percent, 27 percent, and 21 percent lower, respectively for patients subject to
the cap relative to those with full coverage. The cap was also associated with poorer control of blood pressure, lipid levels, and glucose levels, and savings from reduced use of medicines were offset by increases in the costs of hospitalizations and emergency care.

A 2004 RAND study found that doubling copays for medicines reduced adherence by 25-45 percent. As
patients’ use of medicines declined due to increased copays, emergency room visits increased 17 percent and hospital stays rose 10 percent among patients with diabetes, asthma, or gastric acid disorder.