Systemic literature review of the performance of the 2010 ACR/EULAR classification criteria for rheumatoid arthritis: good news of debatable significance

Is the epidemiology of rheumatoid arthritis changing? Results from a population-based incidence study, 1985-2014

OBJECTIVES

To examine trends in the incidence of rheumatoid arthritis (RA) from 2005 to 2014 overall and by serological status as compared with 1995-2004 and 1985-1994.

METHODS

We evaluated RA incidence trends in a population-based inception cohort of individuals aged ≥18 years who first fulfilled the 1987 American College of Rheumatology (ACR) criteria for RA between 1 January 1985 and 31 December 2014. Incidence rates were estimated and were age-adjusted and sex-adjusted to the white population in the USA in 2010. Trends in incidence were examined using Poisson regression methods.

RESULTS

The 2005-2014 incidence cohort comprised 427 patients: mean age 55.4 years, 68% female, 51% rheumatoid factor (RF) positive and 50% anti-cyclic citrullinated peptide antibody positive. The overall age-adjusted and sex-adjusted annual RA incidence in 2005-2014 was 41/100 000 population (age-adjusted incidence: 53/100 000 in women and 29/100 000 in men). While these estimates were similar to the 1995-2004 decade, there was a decline in the incidence of RF-positive RA in 2005-2014 compared with the previous two decades (p=0.004), with a corresponding increase in RF-negative cases (p<0.001). Smoking rates declined and obesity rates increased from earlier decades to more recent years.

CONCLUSIONS

Significant increase in incidence of RF-negative RA and decrease in RF-positive RA in 2005-2014 compared with previous decades was found using 1987 ACR criteria. The incidence of RA overall during this period remained similar to the previous decade. The changing prevalence of environmental factors, such as smoking, obesity and others, may have contributed to these trends. Whether these trends represent a changing serological profile of RA requires further investigation.

The challenge of using the rheumatoid arthritis diagnostic criteria in clinical practice

The new 2010 ACR/EULAR (American College of Rheumatology/European League Against Rheumatism) criteria of Rheumatoid Arthritis recently published, have been released to classify and identify patients with early RA who could benefit from early therapy. They recommend anti-citrullinated protein antibody (ACPA) testing as an alternative criterion to Rheumatoid Factor (RF) and ACPA that were introduced together with the other classic criteria in a scoring system. We previously criticized these new criteria because of unavailable specificity and sensibility in the first paper, and the use of ACPA as dichotomous criterion (presence/absent) and alternatives to rheumatoid factor. Our previous work promoted discussion and fostered new research on this issue. By the light of new data, in an effort to improve clinical reasoning, we suggest a more practical probabilistic point of view. In this regard, we analyze the sensitivity and specificity of the diagnostic studies that evaluate the performance of the 2010 classification criteria. Then, we compare the old and the new classification criteria. Subsequently, we describe the use of likelihood ratios applied to the classification criteria and different cutoff levels of ACPA for decision-making in different setting. Moreover, we define some properties of likelihood ratios and their use for diagnosing or excluding rheumatoid arthritis. We want to share this kind of knowledge within the scientific community because we believe that it can help general practitioners and specialists to recognize early arthritis patients implementing a more efficient probabilistic clinical reasoning.