Arthritis, which includes osteoarthritis (OA), rheumatoid arthritis (RA), or other types, ranks as a leading cause of disability and pain in the United States. “Arthritis accounts for more than 100 million physician and outpatient visits, 1 million hospitalizations, and an estimated $156 billion in medical expenses and lost wages each year,” says Juyoung Park, PhD. “Considering the substantial healthcare resource utilization and economic burden associated with arthritis, it is an important public health interest to understand prevalence trends.”

 

A Welcome Update

For a study published in the American Journal of Public Health, Dr. Park and her colleagues, Angelico Mendy, MD, MPH, and Edgar R. Vieira, PhD, examined the prevalence trends of OA, RA, and other types of arthritis in the U.S. from 1999 to 2014. Data on more than 43,700 community-dwelling adults aged 20 and older who participated in the 1999–2014 National Health and Nutrition Examination Surveys (NHANES) were analyzed. According to the results, the age-adjusted prevalence of arthritis was 24.7%. The breakdown of prevalence rates was 9.7% for OA 4.2% for RA, 2.8% for other types of arthritis, and 8.0% for types of arthritis that were not known by participants. “The prevalence of OA increased from 6.6% to 14.3% over the study period, whereas RA prevalence decreased from 5.9% to 3.8%,” says Dr. Park (Figure).

The observed increase in OA prevalence was significant in both men and women; among non-Hispanic Whites, non-Hispanic Blacks, and Hispanics; and people with high socioeconomic status. The observed decrease in RA prevalence was more pronounced in men; among non-Hispanic Blacks; in participants with low income; and among participants who were obese.

 

Explaining Trends

Dr. Park says it is plausible that the introduction of effective drugs during the study period led to improvements in treatment regimens and a decrease in RA prevalence. “Both diagnosis and the start of pharmacological treatment for RA occurred earlier during our study period, which may have contributed to our findings on RA prevalence,” she says. “The reduced frequency of joint replacements and other joint operations relating to RA may have also had an effect.” Conversely, increases seen in the age-adjusted prevalence of OA were likely a consequence of cumulative exposure to risk factors and biological changes, such as oxidative damage, thinning of cartilage, or muscle weakness.

Contrary to data from other recent data, Hispanics and non-Hispanic Blacks were less likely than non-Hispanic Whites to have arthritis. This finding may be attributable to a lack of adequate healthcare for a correct diagnosis. Other studies suggest non-Hispanic Blacks and Hispanics are more likely than non-Hispanic Whites to use self-care or alternative or complementary medicine and are less likely to receive traditional medical care. The finding that OA was more common in older White women may be explained by age-related degeneration and hormonal changes, like lower estrogen levels, being associated with a higher risk for OA.

 

Important Implications

“Our findings on the prevalence of various types of arthritis can be used to inform clinicians on strategies to improve treatment approaches as well as healthcare policy and reform,” Dr. Park says. “The findings can also be used as a resource to identify and minimize risk factors associated with the increasing prevalence of arthritis. Due to the growing economic and public health burden associated with arthritis, cost-effective rehabilitation programs are necessary to minimize symptoms, maximize functional capacity, reduce disability, and improve quality of life.”

Dr. Park notes that physicians should carefully assess pain symptoms and functional limitations in both younger and older patients, and develop individualized care plans. “Physicians should prioritize cost-effective and safe treatment, especially for groups with the highest prevalence, rather than simply prescribing pain medications,” she adds.

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