DAS and HAQ are acronyms for the two of the most important outcome measures in rheumatology. DAS stands for disease activity score while HAQ stands for health assessment questionnaire. Both are products of genius and have the potential to transform rheumatology care.
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Explore This IssueFebruary 2007
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I mastered the DAS first and, a few weeks ago, tried the HAQ. Alas, my first foray with this instrument went awry after only the second question, when, as they say, I took my eye off the ball.
Treat by Numbers
My interest in adding the HAQ to my clinical repertoire should not be surprising. As a scientist, I believe that quantitation is the bedrock of medical practice as well as research. Furthermore, in my own practice, after incorporating the DAS into regular care, I learned an enormous amount. I have become a cheerleader for this outcome measure much to the amazement of many of my colleagues who do not share my enthusiasm. Indeed, after I extolled the virtues of the DAS at a conference, one of them said, “You should stick a fork in it.”
I started using the DAS in my clinic about two years ago. I had good reasons. First, I am convinced that, for the treatment of RA to advance, rheumatologists must learn to treat by the numbers. While one can debate whether the DAS is better than the DAS28 (and CDAI and SDAI are better than either), the point is that achieving the goal of remission will only happen when the metrics are there. If a clinician believes the patient is doing well, he or she should be able to translate this feeling into a number. Improvement in quality demands the same primacy for metrics.
In thinking about rheumatology today, I worry sometimes that there is too much reliance on intuition. I know that rheumatologists are skilled physicians, proud of their clinical acumen, but we are not seers or diviners and numbers count as well. I was dismayed recently to read an article saying that most rheumatologists “don’t have time to do a DAS.” For the life of me, I cannot figure out what is happening in offices where a simple count of 28 joints represents an unacceptable burden of time. How are providers making decisions if they are not making measurements?
The second reason for my using the DAS has to do with my research. For the past few years, I have been working on approaches to achieve remission in RA, using the DAS to determine this outcome. Unless I understood what a DAS28 of 2.6 really meant, I felt unable to design and conduct a study intelligently.
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.
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.
With the DAS under my belt, I was ready for the next step and would take the plunge that Ted Pincus had been urging on me for years.
For those of you who don’t know him, Theodore Pincus, MD, is a giant of our field, an investigator of vision and passion. No shrinking violet, Ted is always exhorting rheumatologists to use the HAQ and he touts his questionnaires wherever he goes, handing them out like leaflets at a political rally.
Ted was once a basic scientist and knows the value of numbers. He has told me many times that the HAQ gives as much information as the ACR20, 50, or 70 and can match the DAS in its power to illuminate patient outcome. While the data on this point are clear, I was somewhat reluctant to use the HAQ because of the number of questions and their nature—the HAQ Disability Index comprises 20 questions on various activities of daily living. I had perused the questions several times but never really studied their content—a big mistake, as we shall see in next month’s column.
Dr. Pisetsky is physician editor of The Rheumatologist and professor of medicine and immunology at Duke University Medical Center in Durham, N.C.