Every time I see a patient in the clinic, I do a formal count of tender and swollen joints (hands but no feet), get a sed rate, and ask the patient for a global assessment score. Initially, I used a Web site to calculate the DAS, having to Google it every time. Eventually, one of the drug reps gave me a nice little computer for the DAS. I call it my DASometer, and I carry in the pocket of my long white coat every time I go to clinic.
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Explore This IssueFebruary 2007
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The intricacies and vagaries of the DAS fascinate me. When I have a moment free in clinic, I conjure all kinds of combinations to put the DAS through its paces. I punch in numbers to obtain values that come from a formula worthy of nuclear physics in its square roots and logarithms. I also play games and try to figure out which patient has a higher DAS: someone with five swollen joints and a sed rate of 20 or someone with one tender joint and a sed rate of 10. My fellows think I am crazy to pursue these entertainments but there is method to my madness.
My third reason for using the DAS is practical. The DAS helps guide the use of biologics in my clinic where I must approve every prescription for these expensive agents. When one of the fellows asks me for a biologic for a patient, my first question is, “What is the patient’s DAS?” I then examine the patient myself to confirm the number. This endeavor has made the fellows as well as me much more assiduous in our physical exam and has led to discussions of almost a metaphysical import. “What is swelling?” “What is tenderness?” “Can swelling ever go away?”
Surprises and Lessons
In the process of using the DAS, I have discovered that I really don’t understand RA and the meaning of active disease. For example, I saw a patient recently who was a bricklayer working full-time. He was on only methotrexate and, because he was so functional, I thought that the treatment was adequate. A detailed exam showed a slew of tender joints and a bona fide DAS28 of 4.5. I feared that trouble loomed ahead for this man and we began a TNF blocker.
My enthusiasm for the DAS has grown the more I use it,and I asked the drug rep who gave me my DASometer to get one for each of our fellows. Now the fellows are following patients with this measure. I beam as they come to me and say, “I have a patient with RA who has a DAS of 3.9. What do you think we should do?” Like specialists who use cholesterol values as milestones or juggle drugs to keep the blood pressure down, I feel solidly in the mainstream of medicine.
Next Step: The HAQ
I am now pretty good at the DAS and don’t really need the calculator to tell me where I am on the color-coded scale, where green is good and red is bad.