Therapeutic substitution could reduce US drug spending by nearly 10%, study finds

The routine use of therapeutic substitution—where cheaper, chemically different compounds from the same therapeutic drug class are substituted for higher priced brand name drugs—could reduce US drug spending by nearly 10%, a new study in JAMA Internal Medicine has found.1

Unlike generic substitution—where a generic equivalent of a brand name drug is used—therapeutic substitution replaces the brand name drug with a drug with a different active ingredient but the same therapeutic effect, such as reducing blood pressure or cholesterol. While some studies have shown that therapeutic substitution could yield substantial cost savings, the practice is controversial because of safety and efficacy concerns.

To estimate the potential economic impact therapeutic substitution might have on drug expenditure, the researchers used data from the 2010- 2012 Medical Expenditure Panel Survey, a nationally representative survey of the non-institutionalized civilian population of the US.

The study used survey data from 107 132 individuals, of whom 62% reported use of any prescribed medicine. From the participants’ reported prescription drug use, the researchers calculated that the use of branded drugs for which substitution was possible added up to around $73bn in excess spending during the study period. Of this total, $24bn was in excess out-of-pocket spending for patients.

The researchers said, “The excess was present across numerous drug classes throughout many aspects of medicine and equated to 9.6% of total, and 14.1% of out-of-pocket, prescribed medicine expenses.”

Statins, atypical psychotics, selective serotonin re-uptake inhibitors, and angiotensin receptor blockers were the drug classes with the highest excess spending, they said.

“Although therapeutic substitution is controversial it offers a potential mechanism to significantly decrease costs if it can be implemented in a way that does not negatively affect quality of care,” the researchers said.

In an accompanying editor’s note,2 Joseph S Ross, an associate editor of the journal, noted that caution was needed in any program of therapeutic substitution because substitute drugs may not necessarily be as effective and may have different potencies or safety profiles.

“On the other hand, drug companies often market their new drugs as having benefits over existing competitors, even when these benefits have not been substantiated in randomized clinical trials,” Ross said. “To achieve the benefits of within class substitution we need wider adoption of systematic protocols, aligned with physician judgment, as to when such substitutions are beneficial and when not.”