The study estimates that U.S. spending on such drugs will reach nearly $115 billion in 2014. Specialty drugs are defined as drugs used to treat very serious ailments, such as cancer and autoimmune diseases like diabetes. The drugs require special handling and administration.

Their costs are high due to several factors, including the expense of developing them, and the fact that physicians are delaying treatment of some patients until drugs now under development come to market.

Heading the list of expensive specialty drug therapies will be diabetes drugs, where spending on them is expected to increase by 24 percent between now and 2015. (Other disease categories where Express Scripts expects to see higher spending on drugs are cancer, multiple sclerosis, and inflammatory conditions such as rheumatoid arthritis.)

According to Express Scripts, diabetes became the costliest prescription drug therapy class in 2011. The increasing incidence of the disease in the general population, plus an abundance of new diabetes drugs in the pipeline will add to the overall cost of drugs in that class.

Jun 14, 2013