6. Clinical Data Clinical data will be collected as part of routine care, in conjunction with specialist adolescent and young adult rheumatologists in the Arthritis UK Centre for Adolescent Rheumatology at UCLH. Validated clinical measures of disease activity will be documented at each clinic visit such as physician global assessment of disease activity, juvenile arthritis disease activity score (JADAS), Health Assessment Questionnaire (HAQ - measure of function), biochemical (blood) markers of inflammation such as C-reactive protein and erythrocyte sedimentation rate and for ERA validated measure of disease activity for spondyloarthritis will be collected (Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI) and Ankylosing Spondylitis Disease Activity Index (ASDAS). All of the above measures are collected as part of routine clinical care.