WASHINGTON — Prescription abandonment is sharply higher for branded drugs than generic drugs, a new annual report commissioned by the Association for Accessible Medicines (AAM) found.

AAM said Monday that abandonment — defined as the failure to pick up a new script — was nearly three times as high for brand-name drugs as for generics last year, according to the “2017 AAM Generic Drug Access & Savings in the U.S.” study.

Overall, 20.5% of branded scripts were never filled, compared with 7.7% of generics. In addition, branded products account for 20% of approved claims but represent 40% of all abandoned claims for new patients.

Cost plays a significant role in abandonment; 90% of generic co-pays are under $20 versus 39% of branded co-pays.

Also, people who abandoned branded scripts came back to pharmacies and filled generic versions 13% of time, saving an average of $50 in the process, the report found. AAM said 87% of patients save money when switching to a generic alternative.

“New data shows almost 90% of prescriptions are filled by generics, but the costs associated with those medicines have decreased to just 26% of all spending on drugs,” said Chip Davis, president and chief executive officer of AAM. “A priority for our national conversation around drug pricing should be how to ensure generics continue delivering such great access and savings to patients.”

Generic drugs have saved the U.S. health care system $1.67 trillion in the last decade, generating $253 billion in savings in 2016 alone, the study revealed.

Medicare savings from generics amounted to $77 billion, or $1,883 per enrollee, while Medicaid savings were $37.9 billion, or $512 per enrollee. Over the 10-year period from 2007 to 2016, savings from generic drugs totaled  $1.67 trillion.

Nearly 3.9 billion of the total 4.4 billion prescriptions dispensed in the United States are for generics. Generics make up 89% of prescriptions dispensed but only 26% of total medicine spending. Put another way, branded drugs are 11% of prescriptions and responsible for 74% of drug costs.

In 2016, the top 10 products for savings were generic versions of Lipitor ($14.4 billion in savings), Prilosec ($11.1 billion), Zofran ($10 billion), Cymbalta ($8.2 billion), Zocor ($6.9 billion), Neurontin ($5.8 billion), Norvasc ($5.6 billion), Singulair ($4.7 billion), Abilify ($4.6 billion) and Seroquel ($4.5 billion).

The report also looks at state-by-state savings and generic savings by therapy area. The most savings from generic drugs were found in mental health ($44 billion), hypertension ($29 billion) and cholesterol ($28 billion) treatments.