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There is no single laboratory test or procedure that can be used to diagnose RA

Diagnosis and monitoring

Diagnosing and Monitoring RA


  • There is no single laboratory test or procedure that can be used to diagnose RA; instead a set of criteria that includes clinical symptoms (stiffness, swelling), radiographic features and the presence of RF is currently used to establish a diagnosis.1,2
  • Because physical effects of early disease are often subtle, and may overlap with symptoms of other conditions, diagnosis of RA can be challenging.2
  • Early diagnosis and treatment are important, as potentially irreversible joint damage occurs early in the course of disease.3
A number of criteria and composite measures are used to assess disease activity and monitor response to therapy in RA
American College of Rheumatology (ACR) criteria
  • Originally published in 19954
  • A 20% improvement in these criteria, a result that is known as ACR20, requires a 20% reduction in the number of swollen joints on a 68-joint count, in the number of tender joints on a 66-joint count and in three of five of the following criteria:
    • Patient’s assessment of pain
    • Patient’s global assessment of disease activity
    • Physician’s global assessment of disease activity
    • Patient’s assessment of physical function
    • Markers of inflammation (e.g. erythrocyte sedimentation rate [ESR] or CRP)
  • ACR50 and ACR70 similarly require 50% and 70% reductions, respectively5
  • An ACR70 response is sometimes used to refer to a state of clinical remission, although clinical remission is a status rather than a change of disease activity
Disease activity score 28 (DAS28)
  • Disease activity score in 28 joints – a composite numerical score which combines several discrete individual measures of RA activity, such as swollen joint count, tender joint count, ESR and measures of general health status, into a single grading of disease severity
  • Score ranges from 0 to 10 with a higher score indicating a higher disease activity
  • A DAS28 of <2.6 is typically used to define clinical disease remission, although other clinical definitions exist
European League Against Rheumatism response criteria
  • Combines the DAS28 at the time of evaluation with the change in DAS28 between two time points and may be used to define improvement or response to treatment
  • Response categories include good, moderate and low response
Radiographic evaluation
  • Radiography provides an objective measure of the extent of anatomical joint damage
  • A range of radiographic scores are currently used, many of which combine assessments of erosions and joint space narrowing – such as the Sharp score, the Larsen score and modified versions of these scores6
Health Assessment Questionnaire - Disability Index (HAQ-DI)
  • A standardised and widely used patient self-report questionnaire developed to assess the patient's physical function in rheumatic diseases and since applied to a wide variety of other clinical fields7
  • Comprises 20 questions in eight domains; the final score is the mean of the highest scores across the eight domains and ranges from 0 to 3, with higher levels reflecting greater disability8
Functional Assessment of Chronic Illness (FACIT) -Fatigue
  • A short (13-question) validated standard patient self-report questionnaire designed to measure fatigue and its impact on daily function9
  • The FACIT–Fatigue scale ranges from 0 to 52, with higher scores indicating less fatigue
  • There is also a more detailed fatigue questionnaire called FACIT–F
Medical Outcomes Short Form-36©
  • A self-administered patient questionnaire validated as a measure of health-related quality of life in RA patients
  • Comprises eight subscales (domains), which assess different aspects of patient health, and two summary scales (the physical and mental component summary scales)10

References:

  1. Arnett FC, et al. The American Rheumatism Association 1987 revised criteria for the classification of rheumatoid arthritis. Arthritis Rheum 1988; 31:315–324.
  2. O’Dell JR. Therapeutic strategies for rheumatoid arthritis. N Engl J Med 2004; 350:2591–2602.
  3. Lindqvist E, et al. Course of radiographic damage over 10 years in a cohort with early rheumatoid arthritis. Ann Rheum Dis 2003; 62:611–616.
  4. Felson DT, et al. American College of Rheumatology. Preliminary definition of improvement in rheumatoid arthritis. Arthritis Rheum 1995; 38:727–735.
  5. Rindfleisch JA, Muller D. Diagnosis and management of rheumatoid arthritis. Am Fam Physician 2005; 72:1037–1047.
  6. Baron G, et al. Reporting of radiographic methods in randomised controlled trials assessing structural outcomes in rheumatoid arthritis. Ann Rheum Dis 2007; 66:651–657.
  7. Fries JF, et al. Measurement of patient outcome in arthritis. Arthritis Rheum 1980; 23:137–145.
  8. Smolen JS, et al. Effect of interleukin-6 receptor inhibition with tocilizumab in patients with rheumatoid arthritis (OPTION study): a double-blind, placebo-controlled, randomised trial. Lancet 2008; 371:987–997.
  9. Cella D, et al. Validation of the Functional Assessment of Chronic Illness Therapy Fatigue Scale relative to other instrumentation in patients with rheumatoid arthritis. Rheumatology 2005; 32:811–819.
  10. Kosinski M, et al. The SF-36 Health Survey as a generic outcome measure in clinical trials of patients with osteoarthritis and rheumatoid arthritis: relative validity of scales in relation to clinical measures of arthritis severity. Med Care 1999; 37:MS23–MS39.

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