Why is diagnosing rheumatoid arthritis so challenging?

Diagnosing rheumatoid arthritis for many RA patients became a journey that involves several physicians.  Some patients endure symptoms for 1 month to 10 years in the US before diagnosis [1].  More recent studies reported that average lag time between presence of symptoms and diagnosis ranged from 8.8 months in Poland [2], 17 months in Spain [3], 30.2 months in Saudi Arabia [4], 40.2 months in Venezuela [5], to 37.2 to 55.2 months in the US [6].

First of all, rheumatoid arthritis disease can present an overlapping set of symptoms and clinical signs in individual patients.

Second, other diseases can cause stiffness and pain in joints so these other diseases need to be ruled out.

Third, no single test definitively indicates a positive diagnosis of RA.

Fourth, the American College of Rheumatology and other professional societies have NOT published a set of diagnostic criteria as of 2016 [7]

Instead, the main professional society for rheumatologists, the American College of Rheumatology, has published classification criteria in 1987 and 2010. 

Fifth, about 1 in every 6 patients diagnosed with RA do not meet the 1987 or the 2010 RA classification criteria [8]. 

The difference between diagnosing rheumatoid arthritis and classifying it

The goal of diagnostic criteria for RA are to identify all patients with RA.  Diagnostic criteria thus need to be very broad. They include common symptoms, clinical signs, and results of laboratory tests, but also relatively rare symptoms that are found in only some patients. Diagnostic criteria are very useful in a clinical practice [7, 9]

In comparison, classification criteria list a set of symptoms, clinical signs and lab results observed in some rheumatoid arthritis patients.  

  • Physicians use classification criteria to find a group of RA patients who are more similar to each other than the total RA population (called a more homogeneous group or cohort).
  • The classified subgroup of RA patients are often asked to participate in clinical trials to study the causes of RA, find new biomarkers, or measure the response to a new treatment [7, 9].    

Initial steps in diagnosing RA

Rheumatologists examine each patient for the signs and symptoms of rheumatoid arthritis and other potential diseases that can mimic rheumatoid arthritis. 

If no other diseases appear to cause the swollen, painful joint(s), then rheumatologists will likely examine the patient for meeting the classification criteria for RA.

 

 


 

The 2010 Classification criteria for diagnosing Rheumatoid Arthritis at 6 weeks or longer [10]

First, patients should have at least one swollen joint (clinical synovitis) that was not explained by a different disease [10].

If RA is suspected, then the patient should be examined for the presence of four characteristics that indicate a potential RA classification using the 2010 version:

  • involved joints (Group A),
  • RA-associated serology or antibodies (Group B),
  • indicators of ongoing inflammation (Group C), and
  • duration of symptoms (Group D).[10] 

The score for each patient is the sum of the highest score for each group.  Each patient’s score ranges from 1 to 10 [10]. Physicians make a positive RA classification if the patient has a score of 6 to 10 [10].

However, seronegative RA patients are less likely to meet the 2010 RA classification criteria than meet the 1987 RA classification criteria [8].

The 1987 Classification criteria for diagnosing rheumatoid arthritis [11]

Classification of RA by the 1987 revised criteria required a positive finding of 4 of the following 7 criteria [11]:

1.    Morning stiffness:  The affected joints are stiff or less flexible for at least one hour before maximal flexibility occurs or returns.

2.    Arthritis in 3 or more joints:  Physician observes swelling and / or fluid in at least 3 joint areas simultaneously in the legs or arms at the following 14 joints:

  • legs (right or left ankle, knee, first toe joint (proximal interphalangeal joint), the joints between toes and feet (metatarsophalangeal joints) or
  • arms (wrist, elbow, first finger joint (proximal interphalangeal joint), the joints between fingers and hands (metacarpophalangeal joints)

3.    Swollen arthritic joint in the hand:  Physician observes at least one swollen joint in the hand or wrist in the wrist, first finger joint (proximal interphalangeal joint), the joints between fingers and hands (metacarpophalangeal joints.

4.    Symmetric arthritis: Same joints on both sides of the body appear swollen, red, and warm. For example, right and left wrists.

5.    Rheumatoid nodules: Physician observes one or more rheumatoid nodules (hard bumps) just below the skin over bones, joints, or near joints.

6.    Serum Rheumatoid Factor:  Abnormal levels of Rheumatoid Factor.

7.    Radiologic changes:  X-rays of swollen joints display rough, potholed cartilage (erosions) and lower bone mineral density (bony decalcification) near the affected RA joints.  (Changes that indicate only osteoarthritis are scored negative.)

How many newly diagnosed RA patients are in the RA classification subgroups?

Kasturi and colleagues [8] reviewed the medical records of nurses enrolled in the Nurses’ Health Study I and II.  128 nurses reported a new diagnosis of rheumatoid arthritis in 2009 to 2012.

The rheumatologists then assessed the medical records of these 128 nurses to see how many of the nurses were in the 1987 RA classification subgroup and / or the 2010 RA classification subgroup. 

The authors classified 98 of the 128 nurses diagnosed with RA as belonging to at least one of the RA classification groups [8].  More than half of the nurses (56%) were classified as having RA by both sets of classification criteria [8]

The rheumatologists placed about 3 of every 4 of these nurses who were newly diagnosed with RA in a 1987 RA classification subgroup [8].  

Fewer ―about 6 of 10― of these nurses met the 2010 RA classification criteria [8].

How many patients had RA but did not belong in the RA classification subgroups?

Not all patients with rheumatoid arthritis meet the 2010 or the 1987 classification criteria.  For example, Kasturi et al reported that individual rheumatologists had diagnosed:

  • 26 nurses (20%) who met only the 1987 RA classification criteria.
  • 9 nurses (7%) who met only the 2010 RA classification criteria
  • 21 nurses (16%) although each of these nurses did not meet either the 2010 or the 1987 classification criteria [8]

Thus, diagnosing rheumatoid arthritis in one of every 6 patients in a rheumatologists’ clinical practice may require insights on RA beyond the 1987 and the 2010 classification criteria.    

Please remember that classification criteria define the symptoms and signs of only a subgroup of RA patients.      

How many months or years did the diagnosing rheumatoid arthritis take in your case?   Mine was about two years.

 

Selected references

 

1.         Chan, K.W., et al., The lag time between onset of symptoms and diagnosis of rheumatoid arthritis. Arthritis Rheum, 1994. 37(6): p. 814-20.

2.         Kwiatkowska, B., et al., Early diagnosis of rheumatic diseases: an evaluation of the present situation and proposed changes. Reumatologia, 2015. 53(1): p. 3-8.

3.         Hernandez-Garcia, C., et al., Lag time between onset of symptoms and access to rheumatology care and DMARD therapy in a cohort of patients with rheumatoid arthritis. J Rheumatol, 2000. 27(10): p. 2323-8.

4.         Hussain, W., et al., From Symptoms to Diagnosis: An Observational Study of the Journey of Rheumatoid Arthritis Patients in Saudi Arabia. Oman Med J, 2016. 31(1): p. 29-34.

5.         Rodriguez-Polanco, E., et al., Lag time between onset of symptoms and diagnosis in Venezuelan patients with rheumatoid arthritis. Rheumatol Int, 2011. 31(5): p. 657-65.

6.         Molina, E., et al., Association of socioeconomic status with treatment delays, disease activity, joint damage, and disability in rheumatoid arthritis. Arthritis Care Res (Hoboken), 2015. 67(7): p. 940-6.

7.         Aggarwal, R., et al., Distinctions between diagnostic and classification criteria? Arthritis Care Res (Hoboken), 2015. 67(7): p. 891-7.

8.         Kasturi, S., et al., Comparison of the 1987 American College of Rheumatology and the 2010 American College of Rheumatology/European League against Rheumatism criteria for classification of rheumatoid arthritis in the Nurses' Health Study cohorts. Rheumatology international, 2013.

9.         June, R.R. and R. Aggarwal, The use and abuse of diagnostic/classification criteria. Best Pract Res Clin Rheumatol, 2014. 28(6): p. 921-34.

10.       Aletaha, D., et al., 2010 rheumatoid arthritis classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative. Ann Rheum Dis, 2010. 69(9): p. 1580-8.

11.       Arnett, F.C., et al., The American Rheumatism Association 1987 revised criteria for the classification of rheumatoid arthritis. Arthritis Rheum, 1988. 31(3): p. 315-24.

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