The prevalence of functional disability is significantly higher in people with rheumatoid arthritis (RA) than in people without RA regardless of age and sex, and the higher prevalence persists over time. This is a core finding of a retrospective, population-based study from the Mayo Clinic, Rochester, Minn. In the study, investigators assessed the prevalence of patient-reported functional disability associated with RA by comparing the incidence of functional disability of a cohort of patients with RA to a cohort without RA.1
The study’s other key findings were that the excess in the prevalence of functional disability pre-dated the RA incidence rate. Additionally, RA patients who were particularly disadvantaged, with an increasing burden of functional disability over the course of their disease were positive for rheumatoid factor (RF) or anti-cyclic citrullinated peptide (CCP) antibodies.
“This study shows the excess in the prevalence of functional disability in RA predates the RA incidence data, defined by fulfillment of the 1987 ACR criteria for RA, by one to two years,” says the study’s lead author Elena Myasoedova, MD, PhD, assistant professor of medicine, Mayo Clinic.
“Our findings suggest the burden of functional disability affecting most groups of RA patients begins early in the disease course and may precede RA diagnosis,” Dr. Myasoedova says.
Noting that functional disability is a reality for all patients living with RA, Elena Schiopu, MD, associate professor, Department of Rheumatology, Michigan Medicine, University of Michigan, Ann Arbor, says the novelty of the study is that it explores functional disability in the first two years preceding the diagnosis of RA.
“RA does develop in stages, starting with the presence of antibodies, a period of undifferentiated arthritis, followed by the official diagnosis based on fulfillment of classification criteria,” she says. “With musculoskeletal diagnoses leading the causes of disability in the U.S., it’s not surprising that even during the pre-RA phase, there is functional disability.”
The study included 586 patients with RA and 531 patients without RA. All study participants were residents of Olmsted County, Minn., and were 18 years or older. Patients with RA were diagnosed between January 1999 and December 2013 based on the 1987 American Rheumatism Association Criteria for RA, and the incidence date was defined as the earliest date in which the patient fulfilled four or more of these RA criteria.
People in the comparison group without RA were similar to the RA patients in age (56 vs. 55 years old), sex (70% female), smoking history, obesity (39% vs. 40%), use of antidepressants within one year of index date (26% vs. 28%), and calendar year of index (i.e., year corresponding to the incident date of RA patients). Of the patients with RA, 374 (64%) were rheumatoid factor or anti-cyclic citrullinated peptide antibody positive.