The US treatment market for rheumatoid arthritis (RA) is set to increase in value from $6.4 billion in 2013 to $9.3 billion by 2020, representing a Compound Annual Growth Rate (CAGR) of 5.5%, according to business intelligence provider GBI Research.

The company’s report states that this growth will be driven partly by the US’ increasing prevalent population, which is forecast to hit 1.68 million by 2020. Consequently, the country will remain the largest RA therapeutics player of the eight major pharmaceutical markets (the US, UK, Canada, France, Germany, Spain, Italy and Japan) over the forecast period.

Furthermore, Yasser Mushtaq, senior analyst for GBI Research, says the entry of premium-priced, disease-modifying therapies into the US’ RA treatment arena, along with new biosimilar products, will also be a contributing factor to its expansion.

However, as Mushtaq explains: “While the patent expiration of blockbuster drugs as early as this year is expected to cause strong biosimilar uptake in the EU, thereby reducing the Annual Cost of Therapy (ACoT) in this region, these products may not measurably affect the pricing of currently marketed RA treatments in the US.

“Despite the fact that biosimilars are likely to be priced at a discount to their reference drug, the lack of regulatory guidelines for their approvals in the US may deter drug manufactures from seeking marketing approval for these products.”

The analyst adds that drug developers may be further discouraged by state legislation preventing clinicians from taking up biosimilar versions of their reference drugs. This will result in a stable ACoT for RA treatments in the US over the forecast period.

Mushtaq concludes: “The US had the highest ACoT of the eight major markets in 2013, with $5,983, reflecting the country’s higher drug costs in comparison with Canada and the EU. This figure is expected to grow at a CAGR of 3.2% to reach $7,435 by 2020.”