US Arthritis Prevalence Continues Steady Rise; Activity Limitations Grow More Rapidly

Randy Dotinga

October 18, 2021

Nearly a quarter of adults in the United States have been diagnosed with various forms of arthritis, new federal estimates report. The disorders limit the activities of 43.9% of them. Researchers also report that adults with poorer mental or physical health and those who are more disadvantaged socially are most vulnerable to arthritis.

"There is a substantial unmet need for existing, evidence-based, arthritis-appropriate interventions for people with arthritis to minimize activity limitations," study co-author and Centers for Disease Control and Prevention (CDC) epidemiologist Kristina Theis, PhD, MPH, told Medscape Medical News. "Our findings show that interventions addressing self-management, education, physical activity, workplace accommodations, and mental health, among other areas, are all indicated for people with arthritis."

The CDC report was published October 8 in Morbidity and Mortality Weekly Report. Researchers estimated the number of arthritis cases on the basis of in-person interviews conducted with tens of thousands of US adults as part of the National Health Interview Survey during 2016–2018. In the report, the researchers considered arthritis to include general arthritis, rheumatoid arthritis, gout, lupus, and fibromyalgia.

Activity Limitations Rose Faster Than Predicted

According to the report, an estimated 58.5 million US adults (23.7%; 21.5% age-standardized) told interviewers that they had been diagnosed with arthritis conditions. Of those, 25.7 million (43.9%; 40.8% age-standardized) had arthritis-attributable activity limitations (AAALs), which represents 10.4% of all adults.

The number of adults who reported having arthritis rose by 4.1 million from previous estimates for the years 2013–2015, a number that's on pace with predictions. The number in the AAAL category rose by 2 million, a jump that's higher than what had been predicted.

"The aging of the population is one factor in the increasing number of people with arthritis, even though arthritis is not an inevitable part of aging," Theis said. "Individual factors, such as body mass index or other health conditions, and societal factors, such as educational and economic opportunities, likely play a role."

Arthritis was especially common among those aged ≥65 years (50.4%), those who were unable to work or were disabled (52.3%), and those who self-reported fair/poor health (51.2%) or joint symptoms in the past 30 days (52.2%). The rate of arthritis was also high among those whose activities of daily living (ADL) were limited (54.8%) and those whose instrumental activities of daily living (IADL) were limited (55.9%).

The researchers report that the percentage of AAAL was also high among the following groups: "adults with joint symptoms in the past 30 days (51.6%), adults who were unable to work or disabled (54.7%), adults of other/multiple races (54.5%) or non-Hispanic American Indian or Alaska Natives (60.7%), adults with low income (53.3%) or poor/near poor income-to-poverty ratios (63.3%), or with moderate psychological distress (59.5%). AAAL was also reported by a high proportion of adults with arthritis who had an ADL disability (82.6%), IADL disability (80.4%), serious psychological distress (76.3%), or fair/poor self-rated health (72.6%)."

The researchers also found that among all adults with arthritis, the percentage of adults with arthritis was high among women (59.3%), those with obesity or overweight (74.2%), and those who weren't sufficiently active (58%).

Comments on Latest Findings

Michael LaValley, PhD, biostatistician at the Boston University School of Public Health, Boston, Massachusetts, who has studied arthritis statistics, told Medscape Medical News that the findings "fall right in line with the trends that have been observed in arthritis over the past 20 years. The prevalence is increasing, which certainly seems to be influenced by the aging population in the US."

As for specific conditions, he said the rate of osteoarthritis may be influenced by older Americans and by those with obesity and sedentary behavior. "There is also some thinking that there may be environmental factors increasing the risk for some types of arthritis, but nothing conclusive. There also may be more clinical attention paid to arthritic conditions, leading to more people being diagnosed or even just suspecting that they have arthritis."

It's difficult to disentangle connections between arthritis and risk factors such as poverty, he said. "There almost certainly are occupational exposures that put people at risk of osteoarthritis ― having to kneel, stoop, and lift heavy things ― or other musculoskeletal conditions like lower back pain. These exposures are most likely in jobs that would predominantly go to people with few other options because of lower levels of income and education. People in these jobs would also be more likely to have financial stresses that lead to increased psychological distress and less time to take care of their health."

Also, he said, "There is probably some reverse causation with the occupational results, self-related health, and psychological distress. These could all be affected by a person's arthritis. Having arthritis may interfere with getting a better-paying job, and arthritis could certainly reduce someone's self-reported health and induce psychological distress."

The authors and LaValley have disclsoed no relevant financial relationships.

Morb Mortal Wkly Rep. Published online October 8, 2021. Full text

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