The 2010 American College of Rheumatology/European League Against Rheumatism classification criteria for rheumatoid arthritis appear to be more sensitive than the 1987 criteria for the early identification of RA patients, but the two sets of criteria may identify different patient groups, judging from findings presented by Jenny Humphreys, Ph.D.
Looking at 260 patients enrolled in the Norfolk Arthritis Register, a primary care–based inception cohort, who presented between 1990 and 1995 with early inflammatory arthritis symptoms, the investigators found that the 2010 criteria identified as many patients with early RA at baseline as did the 1987 criteria over 5 years, Dr. Humphreys said in an interview at the Annual European Congress of Rheumatology meeting. All subjects were 16 years of age or older at the time they enrolled in the Norfolk Arthritis Register.
Specifically, the incidence rates for RA according to the 2010 criteria were 53.9 cases per 100,000 population for women at baseline and 24.5 cases per 100,000 population for men at baseline, which were similar to the cumulative 5-year incidence rates of 55.7 cases for women and 26.5 cases for men according to the 1987 criteria, said Dr. Humphreys, a clinical research fellow at the Arthritis Research UK Epidemiology Unit, University of Manchester (England).
This suggests that "the 2010 criteria are allowing us to identify these patients earlier on, which is useful," she said, noting that the 1987 criteria identified only 44 cases/100,000 population for women with RA at baseline and only 19 cases/100,000 population for men at baseline.
This is the first study to estimate the incidence of RA using the 2010 ACR/EULAR classification criteria for RA, she noted.
Jenny Humphreys, Ph.D.
"What we have shown is that the incidence of RA using the 2010 criteria is greater when patients first present to health care services," compared with the previous criteria from 1987, Dr. Humphreys said.
However, although the total numbers of patients identified at baseline by the 2010 criteria, and over 5 years by the 1987 criteria, were similar, those identified "were not exactly the same group of patients," she noted.
For example, 4% of patients who satisfied the 1987 criteria cumulatively over 5 years never satisfied the new criteria, and 14% who satisfied the new criteria never satisfied the 1987 criteria. The patients who satisfied the earlier criteria but not the new criteria had more hand joint involvement, symmetrical arthritis, and morning stiffness than did those who satisfied both sets of criteria or just the 2010 criteria.
"This means we need to explore in detail the long-term outcomes in those patients who only ever meet one criteria set," Dr. Humphreys said.
The incidence of a disease is always important in health economics because it gives an idea of the frequency of its occurrence in the population, and resources may be allocated based on this. In addition, it has been suggested that the 2010 criteria could be used as eligibility criteria for certain interventions in RA patients, although this has not been validated and is not currently recommended. "Our data suggest that if that were the case, similar amounts of resources would be required but they may need to be made available earlier, when patients first present with symptoms," she said.
Dr. Humphreys reported that she had no financial conflicts of interest that were relevant to this research.