"The lifetime risk of RA is commonly misunderstood and miscommunicated as a risk of about 1 in 100 based upon the prevalence of RA, which is 0.5% to 1%," say Dr Sherine E. Gabriel and colleagues from Mayo Clinic College of Medicine, Rochester, Minnesota.
"The lifetime risks of RA and other rheumatic diseases have not been estimated previously."
To address this issue, the authors used data from the Rochester Epidemiology Project to estimate the lifetime risk of RA and other rheumatic diseases, including systemic lupus erythematosus (SLE), psoriatic arthritis (PsA), polymyalgia rheumatica (PMR), giant cell arteritis (GCA), ankylosing spondylitis (AS) and Sjögren's syndrome (SS).
The cumulative lifetime risk of developing adult-onset RA in the year 2000 was 3.6% for women (about 1 in 28) and 1.7% for men (about 1 in 59).
The cumulative risk of RA rises steeply around age 60 years in both men and women (the age at which the incidence of RA is highest) and flattens after age 80 years.
Results were similar in the year 1970, when both incidence and mortality rates were substantially higher than current rates, and 1980, when incidence and mortality rates were declining.
The investigators estimate the lifetime risk of any of the inflammatory autoimmune rheumatic diseases at 8.42% for women (about 1 in 12) and 5.13% for men (about 1 in 20).
The incidence of primary inflammatory autoimmune rheumatic diseases peaks near age 80 years in both men and women.
Smaller than lifetime risks
The lifetime risks of RA and primary inflammatory autoimmune rheumatic disease, while greater than previously understood, are nevertheless smaller than the lifetime risks of such common conditions as hip fracture (15.8% for women and 6% for men at age 50) and dementia (10% overall at age 70).
"These results can serve as useful guides in counselling patients regarding their lifetime risk of these conditions and have important implications for disease awareness campaigns," the researchers conclude.
Further investigations are needed "to determine whether identification of persons with high genetic risk for rheumatoid arthritis might justify early detection and intervention to prevent progression to overt clinical disease," they add. (Reuters Health / January 2011)
Arthritis and exercise
Joint Pain/Arthritis News