COPENHAGEN — A new way to assess disease activity in ankylosing spondylitis patients showed good correlation with the Bath score and good responsiveness as patients improved with treatment in an analysis of 60 patients.
The Ankylosing Spondylitis Disease Activity Score (ASDAS) “seems like a promising new tool for assessing disease activity and treatment response,” Dr. Susanne J. Pedersen said at the annual European Congress of Rheumatology. But it needs further validation in larger numbers of patients, and further adjustment to more reliably assess patients with low or high levels of treatment response, said Dr. Pedersen, a rheumatologist at Herlev (Denmark) University Hospital. The ASDAS is based on five clinical elements: back pain, duration of morning stiffness, patient's global assessment, peripheral pain and swelling, and serum level of C-reactive protein (Ann. Rheum. Dis. 2009;68:18-24).
To test correlations of the ASDAS with other assessment methods and to track its change with treatment, Dr. Pedersen and her associates used data from 60 AS patients collected as part of a Danish longitudinal study of AS, known as BIOSPA. The patients met the European Spondyloarthropathy Study Group criteria for spondyloarthritis, had sacroiliitis on MRI or x-ray, and had a BASDAI (Bath AS Disease Activity Index) greater than 30 despite treatment with an NSAID. Their average age was 40 years, 80% were men, and their average disease duration was 12 years. Their average ASDAS at baseline was 3.86, and their average BASDAI was 55.
About two-thirds (68%, or 41) of the patients received infliximab (Remicade), 13 (22%) got etanercept (Enbrel), and 6 (10%) got adalimumab (Humira). Patients were assessed at baseline, and after 22 and 46 weeks of treatment. A total of 53 of the 60 (88%) patients finished 22 weeks of treatment, and 47 (78%) completed 46 weeks of treatment.
Measurement of their ASDAS, BASDAI, and other measures of disease activity at baseline and after 22 weeks of treatment showed good correlation between the ASDAS and BASDAI scores. Among patients with a BASDAI greater than 40 at baseline, a change in the BASDAI of 20 (a common minimum criterion for improvement on treatment) correlated with a change in the ASDAS of 1.38. A change in the BASDAI of 50% (another common criterion for improvement) correlated with an ASDAS improvement of 1.95, Dr. Pedersen said.
Dr. Pedersen and several of her coauthors on the study disclosed financial relationships with Abbott, the company that markets adalimumab. Two of her coauthors had similar relationships with Wyeth, the company that markets etanercept, and one coauthor had similar relationships with Centocor Inc., the company that markets infliximab.