- Arthritis is the leading cause of disability in the United States.
- In this country, about one of every six people (43 million) has arthritis, and the disease limits the daily activities of seven million people.
- Approximately 21 million Americans suffer from osteoarthritis; 75% of them are women. By 2020, if current rates continue, 60 million people will have the disease, and 11 million will have activity limitations.
- Forty percent of people with arthritis are age 65 or older.
- Pharmaceutical agents are available to control the disabling symptoms, especially pain, of arthritis.
Arthritis is not a single disease but rather it is an umbrella term for a group of more than 100 conditions that involve the joints and surrounding tissues, including osteoarthritis, rheumatoid arthritis, gout, and bursitis. (CDC 1999) All of these conditions can decrease quality of life, causing pain and limiting people’s ability to engage in the activities of daily living. Besides the physical toll, arthritis costs the U.S. nearly $65 billion annually. (CDC 2002) Although cost-effective interventions are available to reduce the burden of arthritis, they are currently underutilized.
Percentage of Adults with Arthritic Symptoms by Age, 2000
Note: Respondents were asked if they had experienced pain, aching, stiffness, or swelling in or around a joint that was present most days for at least one month.
Source: National Health Interview Survey, 2000
New treatments for arthritis
COX-2 inhibitors represent a newer class of medications used to treat arthritis. COX-2 inhibitors interfere with an enzyme that causes pain and swelling. Moreover, these drugs do not inhibit the COX-1 enzyme, which may help maintain the normal stomach lining. Thus, COX-2 inhibitors are reported to have less gastrointestinal side effects than older drugs, such as aspirin or other nonsteroidal anti-inflammatory agents. (Silverstein 2000; Bombardier 2000) Included in the COX-2 class are rofecoxib and celecoxib.
Despite the wide availability and use of COX-2 inhibitors in the U.S., some countries restrict coverage of these agents or provide no coverage at all. New Zealand has not approved reimbursement for Celebrex® or Vioxx®, both COX-2 inhibitors. (PHARMAC 2002) In Ontario, Canada, reimbursement for Vioxx® is limited to patients with osteoarthritis who have failed prior treatment with acetaminophen, and who have a history of documented, clinically significant ulcer or gastrointestinal bleeding, or failure or intolerance to at least three other non-steroidal anti-inflammatory agents. (Ontario Ministry of Health and Long Term Care 2002) In addition, reimbursement for this drug is limited to a maximum daily dose of 25 mg, which is not always sufficient to provide effective control of symptoms.
Recent advances in biotechnology have produced novel approaches to treat arthritis. Biologic response modifiers are genetically engineered substances used to reduce the signs and symptoms of rheumatoid arthritis. (Paget 2002) Drugs in this class include etanercept, anakinra, and infliximab. Etanercept, the first in this new class of drugs, acts by inhibiting tumor necrosis factor (TNF), one of the proteins that plays an important role in the cascade of reactions that causes the inflammatory process of rheumatoid arthritis, resulting in significant reduction in inflammatory activity. Infliximab, a monoclonal antibody, also inhibits TNF. Anakinra is a recombinant IL-1 receptor antagonist that also modifies the inflammatory response.
Both etanercept and infliximab are approved by the FDA, but have limited availablity in other countries. These drugs are not covered in New Zealand, or Ontario, Canada and their use in the UK is restricted to patients who have failed arthritis treatments with other medications. (National Institute for Clinical Excellence 2002; PHARMAC 2002; Ontario Ministry of Health and Long Term Care 2001)
Drugs in the pipeline for arthritis
- Additional inflammatory response modulators to reduce the inflammation of arthritis are being studied. (Koopman 2001)
- A vaccine for rheumatoid arthritis which would prevent the autoimmune response is in development. (PhRMA 2002)
Pharmaceutical approaches that modify the inflammatory or immune response are likely candidates for new drugs to treat arthritis. (Koopman 2001) In 2002, eight new drugs for osteoarthritis were undergoing clinical trials. (PhRMA 2002) In addition, clinical trials for 22 new medications for rheumatoid arthritis, including a vaccine to prevent the autoimmune process that causes the disease, were in progress in 2002. (PhRMA 2002)