An estimated 119 million Americans over the age of 12 take prescription medication, according to figures from the National Survey on Drug Use and Health. However, many struggle with the rising cost of their medicine, even those with health insurance to help them afford the required medication. 

The latest Consumer Reports Best Buy Drugs Prescription Costs and Concerns survey, published earlier this month, found one-quarter of patients with prescription needs experienced an increase in the cost of their medication over the last 12 months. The organization suggested three reasons why patients who had health insurance were still affected by rising drug prices.

It suggested patients with with high-deductible insurance plans are still liable for the full price of a drug until they meet their deductibles. One in three Americans with health insurance through their employers are on high-deductible plans, according to figures from the Kaiser Family Foundation. These plans feature increased cost sharing and copayment, but this results in patients absorbing some of the costs when the price of medication rises. 

Changes in insurance company formularies was also cited by Consumer Reports as a contributor to the increase in prices experienced by some patients with insurance. Insurers sometimes move medication from lower, cheaper tiers to higher tiers, resulting in patients forking out a higher co-pay. These changes are usually made at the start of the year, but one survey found up to half the insurers examined dropped or reduced coverage in the middle of the year.

Stephen W Schondelmeyer, professor of pharmaceutical economics at the University of Minnesota, explained: "Increasingly, as drug prices go up, there's a tendency by insurance companies to move your medications to a higher-cost tier… That forces you to either pay the higher cost or switch medications." He suggested patients check the drugs they require are covered in their plans before signing up or renewing a policy. 

Finally, Consumer Reports pointed to the high cost of certain medications as one of the contributing factors in increasing the price of other drugs. It noted medication such as Copaxone (used to treat patients with rheumatoid arthritis) and multiple sclerosis medication Humira cost around $4,500 a month. This is significantly more than commonly prescribed drugs such as Lipitor or Prozac. 

Schondelmeyer explained insurance companies pass on the high cost of rarer drugs to all customers by raising monthly premiums and lowering coverage for other, less pricey medicine. "Those high prices are part of why insurance companies continue to raise your out-of-pocket costs and premium," he asserted.