The prevalence of rheumatoid arthritis (RA) has been significantly underestimated, particularly among younger individuals, according to a new report. A potentially crippling disease, RA can be tricky to diagnose early and expensive to treat.
The report, released in Arthritis and Rheumatology in January 2018, shows that 19.3% of men and 16.7% of women aged 18 to 64, and 15.7% of men and 13.5% of women over age 65 report joint-symptoms but don’t have doctor-diagnosed arthritis. Overall prevalence of arthritis, including both diagnosed and undiagnosed cases, is 29.9% in men and 31.2% in women aged 18 to 64, and 55.8% in men and 68.7% in women over age 65, according to the report.
These estimates, gleaned from an analysis of the 2015 National Health Interview Survey (NHIS), are 68% higher than previous prevalence estimates, which relied merely on a single survey question and did not correct for measurement errors.
Treating RA takes up a huge market share for pharmaceuticals, with one RA biologic—Humira—earning the top spot as the world’s best-selling drug for several years. But as more biologics and biosimilars hit the market, it’s important to consider the big picture in RA management.
Janus kinase inhibitors
Miriam Cohen, MD, is an assistant professor of medicine at the Johns Hopkins University School of Medicine whose clinical expertise is in clinical and molecular rheumatology. She says Janus kinase (JAK) inhibitors are the big topic in RA treatment lately, and will likely be the next step in care from RNF-inhibitors “RA seems to be the one area that’s taking off with new medications and biologics,” Cohen says. “The idea is to be more selective.”
While JAK inhibitors seem to target RA very well, some concerning side effects must be addressed before more widespread adoption, she says. Side effects can be similar to old disease-modifying antirheumatic drugs (DMARDS), spurring concerns with blood counts and hepatic function. Cohen says there are also concerns with lipid levels, cardiovascular disease, and bowel issues. Cohen would also like to see an oral formulation for these medications.
One JAK inhibitor that was approved by the FDA is tofacitinib (Xeljanz), a twice-daily pill that can also be used to treat psoriatic arthritis. “It’s exciting because it’s a different approach to treatment, and involves a different arm of the immune system,” Cohen says.
Other companies are looking at the JAK 1, 2, and 3 enzymes, she says. Aside from JAK, though, she says there are also new developments with TNF- and RNF- inhibitors, as well as biosimilars.
Though there are more options than ever, Cohen says clinicians are also slower to adopt biosimilars. “There’s a lot of suspicion and wariness of how they work in terms of response and effectiveness.”
Erin Bauer, MD, is a board-certified rheumatologist practicing at Virginia Mason Medical Center in Seattle, agrees, adding that there has also been some availability and logistic problems with biosimilars. Bauer also agrees that the market for biologics will continue to grow, particularly in the area of JAK inhibitors.