In early 2019, Jennifer Hepworth and her husband were stunned by a large bill they unexpectedly received for their daughter's prescription cystic fibrosis medication. Their payment had risen to $3,500 from the usual $30 for a month's supply.

That must be a mistake, she told the pharmacy. But it wasn't. It turned out that the health insurance plan through her husband's job had a new program in which it stopped applying any financial assistance they received from drugmakers to the family's annual deductible.

Insurers or employers can tap into funds provided to patients by drugmakers through copay assistance programs, which were designed by the companies to help patients afford increasingly expensive medications. But, because those payments are no longer counted toward the deductible, patients must pay an amount out-of-pocket, too, often for the same drugs. Those deductibles or other out-of-pocket costs can easily run into thousands of dollars.