RA seronegative or seropositive?

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Dear all,

Just need to find out whether Rheumatoid Arthritis (RA) is serongeative or seropositive? As the condition may occur with or without the presence of rheumatoid factor in 15 to 20% of case ,does it belong to both categories?

Would appreciate your opinion in this matter.

Thank you

 

Rheumatoid arthritis is rheumatoid arthritis if it meets the criteria for diagnosis (there has been a recent suggested change in that criteria). One of those criteria is they are seropositive for RA factor ... it is still rhematoid arthrtis if they do not have it, as long as they meet enough of the other criteria.

If they do not have the factor, they are not considered as part of the seronegative group Which include, for eg AS, PA, Reactive artictris and the undifferentiated forms).

The significane of the RA factor is that if its present, there tends to be a not as good of a long term prognosis.

 

Hi,

Just to clarify are you suggesting that RA cannot be classed as seronegative even when RF is absent? In a few aricles it has been classed in either categories depending on whether the RF is present.

Thanks

 

I think you might be confusing the clasification between rheumatoid arthritis and the seronegative spondyloarthropathies with the presence/absense of Rheumatoid factor. The classification into those groups is based on a set of criteria. Rheumatoid arthritis may be seronegative or seropositive for the rhematoid factor. If it is seronegative for RF, that does not move it into the seronegative spondyloarthropathy group.

 

OK ,so RA belongs to seropositive group regardless of RF.
Sorry its the day before the finals,got a bit mixed up.

Thanks for your feedback.

 

Yes.

Historically, they were all rheumatoid arthritis as the joint problems all looked about the same. Then some were identified as 'variants' as they did share some features in common with each other and were a bit different to the classic rheumatoid arthritis.

Then along came sero testing and they were divided in the the rheumatoid factor positive and negative groups. Most of the 'variants' were seronegative for rheumatoid factor; but some of them still had all the classic rheumatoid arthritis features and did not share some of the other features of the other variant that were seronegative (eg the sacroilitis).

Over time with the better understanding of the concept of 'pattern recognition'; the advent of understanding of the HLA's (esp B-27), and then the application of the diagnostic criteria, there was a clear distinction between the seronegative group and true rheumatoid arthritis that was not based on the presence or absence of rhematoid factor.

The only real role that rheumatoid factor now plays is that it is just one of a number of criteria that are part of the 'pattern recgnition' for the diagnostic criteria and its a good prognostic indicator (its presence is usually asssociated with worse outome and more extra-articular features).

The 1987 ARA Criteria for Classification of Rheumatoid Arthritis:
Any four of the following criteria must be present to classify patients as having RA:
• morning stiffness (> 1 hr for more than 6 weeks)
• arthritis of three or more joints for greater than 6 weeks
• arthritis of hand joints for more than 6 weeks
• symmetrical arthritis for more than 6 weeks
• rheumatoid nodules
• serum rheumatoid factor
• radiographic changes (including erosions or bony decalcification)

The new suggested guidelines are:
Patients are definitively diagnosed with RA if they score 6 or more points:
Domain: Joint involvement
– 1 medium-large joint (0 points)
– 2-10 medium-large joints (1 point)
– 1-3 small joints (2 points)
– 4-10 small joints (3 points)
– More than 10 small joints (5 points)

Domain: Serology
– Not positive for either rheumatoid factor or anti–citrullinated protein antibody (0 points)
– At least one of these two tests are positive at low titer, defined as more than the upper limit of normal but not higher than three times the upper limit of normal (2 points)
– At least one test is positive at high titer, defined as more than three times the upper limit of normal (3 points)

Domain: Duration of synovitis
– Less than 6 weeks (0 points)
– 6 weeks or longer (1 point)

Domain: Acute phase reactants
– Neither C-reactive protein nor erythrocyte sedimentation rate is abnormal (0 points)
– Abnormal CRP or abnormal ESR (1 point)

 

Just want to say your indepth description really helped me with my revision.

Thanks again.