Van der Heijde et al developed disease activity scores (DAS) for patients with rheumatoid arthritis. These can be used to monitor patients and to evaluate the effectiveness of therapeutic interventions. The authors are from Nijmegen in The Netherlands.
Parameters:
(1) Ritchie score – range 0 to 46
(2) number of swollen joints- range 0 to 36
(3) erythrocyte sedimentation rate (ESR) in mm during first hour
(4) general health status using a 100 mm visual analogue scale (VAS) – range 0 to 100, with 100 indicating worst possible health imaginable
DAS score using 4 variables =
= (0.53938 * (SQRT(Ritchie score))) + (0.06465 * (number of swollen joints)) + (0.330 * LN(ESR)) + (0.00722 * (general health VAS score))
DAS score using 3 variables =
= (0.53938 * (SQRT(Ritchie score))) + (0.06465 * (number of swollen joints)) + (0.330 * LN(ESR)) + 0.224
where:
• The only difference between the 2 scores is that 0.224 is used in the 3-variable score instead of the general health VAS component. This corresponds to a VAS score of 31, which was the mean VAS score.
Interpretation:
• minimum score: 0 (no disease activity)
• maximum score: around 8.16
• The higher the score, the greater the disease activity.
difference in scores after therapy =
= (initial score) – (current score)
|
Current Score
|
Difference in scores
|
Response
|
|
<= 2.4
|
<= 0.6
|
no response
|
|
|
0.61 to 1.2
|
moderate response
|
|
|
> 1.2
|
good response
|
|
2.41 to 3.7
|
<= 0.6
|
no response
|
|
|
0.61 to 1.2
|
moderate response
|
|
|
> 1.2
|
moderate response
|
|
> 3.7
|
<= 0.6
|
no response
|
|
|
0.61 to 1.2
|
no response
|
|
|
> 1.2
|
moderate response
|
from Table III page 5, van Riel (1996)
where:
• In van Riel et al the maximum swollen joint is listed as 44, while van der Heijde uses 36.
