Artritis Reumatoide

Best Practice & Research Clinical Rheumatology Vol. 19, No. 1, pp. 55–72, 2005
doi:10.1016/j.berh.2004.08.005 available online at http://www.sciencedirect.com

4 Early diagnosis of rheumatoid arthritis
Henk Visser* MD, PhD Rijnstate Hospital, Wagnerlaan 55, P. O. Box 9555, 6800 TA Arnhem, The Netherlands
Early diagnosis of rheumatoid arthritis (RA) is an important challenge for clinicalrheumatologists. This is because there is substantial evidence that early treatment with disease-modifying antirheumatic drugs leads to a better disease outcome. The 1987 American College of Rheumatology classification criteria for RA do not perform well as a diagnostic tool in early arthritis. Therefore, diagnostic studies are needed to develop diagnostic criteria or prediction models that enableclinicians to distinguish RA from other arthritides in an early phase of the disease. Diagnostic studies are hampered by the lack of an independent gold standard for RA. Since the most important clinical features of RA are the persistence of the arthritis and the development of erosions, arthritis outcome is a clinically relevant gold standard. Diagnosis is a phased, multivariable process in which theprobability of the presence of disease is updated continuously when new diagnostic information is added to the patient profile. Therefore, besides univariate studies, multivariable diagnostic studies are needed to evaluate the value of current diagnostic practice or to evaluate the added value of a new diagnostic procedure. This chapter describes univariate and multivariate studies that have beenperformed in early arthritis populations to assess the diagnostic value of medical history, physical examination, laboratory tests and imaging in RA diagnosis. Key words: rheumatoid arthritis; diagnosis; arthritis outcome.

THE IMPORTANCE OF EARLY DIAGNOSIS Rheumatoid arthritis (RA) is a systemic auto-immune disease, with a main characteristic of persistent joint inflammation that results injoint damage and loss of function. Numerous studies have shown that substantial irreversible damage occurs within the first 2 years, as evidenced by the maximal rate of erosive joint disease during this period.1,2 There is now growing evidence that therapeutic intervention early in the disease course of RA leads to earlier disease control and less joint damage.3–5 Moreover, recent years have shownrapid development of powerful and expensive therapeutic agents for RA.6 However, in the majority of early arthritis patients who are not diagnosed as RA, the disease is self-limiting.7 Since treatment of early arthritis with
* Tel.:C31 26 3786575; Fax:C31 26 3786612. E-mail address: hvisser@alysis.nl 1521-6942/$ - see front matter Q 2005 Elsevier Ltd. All rights reserved.

56 H. Visserdisease-modifying antirheumatic drugs (DMARDs) is only justified when the riskbenefit or cost-effectiveness ratios are favourable, it is mandatory to be able to differentiate between RA and other forms of arthritis soon after symptom development. RA should be considered as a medical priority that requires prompt diagnosis and appropriate treatment.8

WHAT IS THE GOLD STANDARD? A problem in the diagnosticresearch of RA is the lack of an independent gold standard. RA has no disease-specific clinical, radiological or immunological features. In most studies, either the physician’s clinical diagnosis or the disease classification according to the 1987 American College of Rheumatology (ACR) classification criteria has been used as the gold standard. A drawback of these gold standards is that they aredependent on the diagnostic tests that are evaluated. This leads to circularity and overestimation of the diagnostic properties of these tests. Another drawback of the use of classification criteria is that approximately 15% of patients with persistent arthritis do not fulfil any of the international classification criteria, even at 2-year follow-up.9 These forms of arthritis are then classified as...