Day #15 - Acute Polyarthritis

Today we discussed a case of a 32 year-old woman with acute/sub-acute onset polyarthritis. The discussant worked us through the differential diagnosis and how to use the history, physical and investigations to arrive at a more definitive diagnosis.

In making a diagnosis we use clinical and laboratory factors. There are diagnostic criteria for each condition which are helpful epidemiologically but can also point out some of the key features of the illness. Recognize that not having all the criteria does not necessisarily mean the patient doesn't have the disease! Just not from a formal epidemiological point of view.

For RA one needs 4/7 of the following (ACR Criteria circa 1980):

1. Morning stiffness lasting >=1 hour
2. 3 or more joints with effusions as examined by a physician. Most commonly wrists, knees, MCPs, PIPs, knee, ankle, MTP
3. Involvement of joints of the hand (wrist, MCP, PIP)
4. Symmetric involvement of similar joints on both sides of the body
5. Rheumatoid nodules
6. Rheumatoid Factor
7. Typical radiographic changes

NB: 1-4 need to be present for >=6 weeks

For SLE one needs 4/11 which I like the mnemonic MD-SOAP-N-HAIR:

1. M - malar rash
2. D - discoid rash
3. S - serositis (pleuritis, paricarditis, rarely peritonitis)
4. O - oral/nasal ulcerations (typically painless, but can be painful)
5. A - Arthritis - symmetric, non-erosive polyarthritis usually involving hands
6. P - Photosensitivity
7. N - Neurologic - seizures or psychois
8. H - Hematologic - Hemolytic anemia or leuko/lymphopenia (unexplained) or thrombocytopenia (unexplained) and persistent
9. A - ANA positive
10. I - Immunologic - Anti-DSDNA, Anti-Sm, Antiphospholipid antibodies
11. R - Renal - Proteinuria or active sediment (casts)
    

In this case, it was rheumatoid arthritis and we then discussed initiating management. The key is to remember that DMARDs take time to work and you will need to use something (NSAIDs if mild, PREDNISONE if moderate-severe) until the DMARDs work.

I also found a great site today, www.rheumatology.org, which has a number of good teaching materials under "Students and Residents".