I went to the DAS workshop at the BSR conference in Liverpool a few years ago. NRAS assisted by providing suitable people to act as 'guinea pigs'. I was one of those lucky people and I am now a whole lot wiser about the overall process for determining disease activity and subsequent drug treatment.
The DAS used in rheumatology units is the DAS 28. This involves assessment of 28 joints in the hands (10 each), wrists (1 each), elbows (1 each), shoulders (1 each) and knees (1 each). Each joint is checked for tenderness and swelling and scored on a chart accordingly. There are other DAS methods available, DAS 56 and I think, DAS 78. It was found that the DAS 28 provided very similar results in terms of synovitis in the joints representative of disease activity throughout the body as those used for checking many more joints. Obviously the time involved in checking 78 joints is rather more than 28 and it is now standard practice to use the DAS 28 method.
I often wondered about why feet were not included in the assessment. In my case it was my feet that were the first to show significant joint damage and subsequent surgery to remove badly damaged metatarsal heads. Due to the damage they are often more painful than other bits. I am assured however that this is due to joint damage and not, for the main part, ongoing disease activity. It was stressed that the feet are most likely to 'feel bad' because they're in constant use and most RA sufferers will have painful feet. By including everyone's feet would simply mean altering the levels of the scores. Seems reasonable!
The scoring is done using a special DAS calculator and combines the tender joints, the swollen joints (ie those showing synovitis), the ESR and the VAS and a couple of factors thrown in! The ESR provides a vital element in the DAS (Disease Activity Score) and, although no-one may be mentioning it specifically, it is used in the calculations.
The VAS is a visual analogue scale. It's the chart which shows how you rate your overall well being and how active you feel your arthritis has been in the previous week.
Pain and fatigue are not taken into account in the DAS but these should be mentioned and noted on your file.
Basically it's best to be completely honest on the day you go for assessment. The nurse will be able to tell from the joint check how bad the problems are. If you're having a particularly good day it's always worth mentioning so that if necessary you can be recalled for further investigation when things are bad. At the end of the day you need to receive treatment that is appropriate for your condition otherwise you won't benefit to the maximum. Drugs can always be adjusted, up or down, as necessary but the starting point needs to be right for you.
DAS less than 2.6 ... .Disease remission
2.6 - 3.2 ... ... ... ... ... Low disease activity
More than 3.2 ... ... .. May require change in treatment for some patients
More than 5.1 ... .... ..Severe disease activity
NRAS provide a good publication on DAS and a DVD to accompany it. Worth requesting if more information would be helpful.
Questions about DAS often come up. Hope this is useful to someone!