ASSESSMENT OF ACTIVITY IN CHILDREN WITH ENTHESITIS RELATED ARTHRITIS USING BATH ANKYLOSING SPONDYLITIS DISEASE ACTIVITY INDEX

Background: Enthesitis related Arthritis (ERA), as defined by ILAR criteria, is characterized by involvement of entheses and the axial skeleton in addition to the pheripheral joints. The clinical spectrum of ERA overlaps with that of spondyloarthropathy. Bath Ankylosing Spondyliyis Disease Activity Index (BASDAI) is a score designed to determine the degree of activity in patients with Ankylosing Spondylitis. Its value as an outcome measure in children with ERA has not been tested Objectives: To study the usefulness of BASDAI in children with ERA and to correlate with disease activity markers. Methods: Consecutive patients with ERA with disease duration ≥ 1 years were included. Patients were seen at the pediatric rheumatology clinic of a tertiary hospital since disease onset (defined as the first 6 months). Only patients with complete records were included. BASDAI was collected at baseline and longitudinally. Variables recorded at first visit: age, sex, presence of axial involvement (spinal pain, reduced spinal mobility or chest expansion), enthesitis, HLA B27, number of active joints, number of joints with reduced mobility, duration of stiffness (minutes), ESR (mm/h), physician`s global evaluation of activity(phy), patient`s assessment of well-being (p) and pain meassured on a 10 cm visual analogue scale (VAS), Bath Ankylosing Spondylitis Functional Index (BASFI) and CHAQ scores. Scores were administered by a pediatric rheumatologist (MK). Association between disease activity markers: ESR, number of active joints, phyVAS, pVAS, painVAS and BASDAI score was sought (Fisher Exact Test, Spearman`s correlation). Correlations were: high≥0.7; moderate= 0.4 to 0.7; or low: <0.4. BASDAI score before and after treatment was compared. Results: 37 patients were enrolled (34 M,3 F). Age at onset: 9±2.7 (3-14) years. Axial involvement: 75%. Enthesitis: 57%. Presence of HLA B27: 48%. BASDAI >0 was observed in 33 (89%) patients. Median BASDAI score at first visit: 2.50 (0-5.20). Follow up: 4±2.4 (1-12) years. BASDAI correlated with: BASFI (r:0.71; p=0,002), pVAS (r:0.66; p=0,005), duration of stiffness (r:0.63; p=0,009), pain (r:0.62; p=0,01), CHAQ (r:0.60; p=0,01), phyVAS (r:0.58; p=0,02), number of active joints (r:0.55; p=0,02), ESR (r:0.54; p=0,003). BASDAI showed significant change before and after treatment with MTX or anti TNF agents (p=0.03). Conclusion: BASDAI showed moderate correlation with activity disease markers. It is sensitive to changes after treatment. BASDAI should be included as a useful outcome measure in the asssessment of activity in children with ERA. References: 1. Calin A. Defining disease activity in Ankylosing Spondylitis: is a combination of variables (Bath Ankylosing Spondylitis Disease Activity Index) an apropiate instrument?. Rheumatology 1999;38(9):878-82. Disclosure of Interest: None declaredCitation: Annals of the Rheumatic Diseases, volume 69, supplement 3, year 2010, page 633Session: Paediatric rheumatology (Poster Presentations )