Background Juvenile idiopathic arthritis (JIA) is a disease which maintains specific childish rheumatological features during whole life. There is still an open discussion which criteria of the disease activity should be used for the management of adult patients with JIA.

Objectives To analyse the usefulness of known disease activity and functional indices used in adult rheumatological practise for the assessment of rheumatoid arthritis (RA) and spondyloarthritidies (SpA): disease acitivity score (DAS), disease acitivity score 28 (DAS28), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Spondylitis Functional Index (BASFI), Health Assessment Questionnaire – disability index (HAQ-DI), short form health survey with 36 questions (SF-36).

Methods 35 adult patients with JIA (polyarticular form) classified by the ILAR (International League of Asociations for Rheumatology) classification criteria (Durban 1997, Edmonton 2001) were assessed clinically initially (I) and after 1 year (II) using DAS, DAS28, BASDAI, BASFI, HAQ-DI, SF-36.

Results 35 adult patients with JIA (polyarticular form) 19.4 (SD 1.8) years old with disease duration 6.5 (SD 4.2). 16 patients receive anti-TNF therapy and 19 patients methotrexate monotherapy. DAS 28 (I) 3.10 (IQR = 2.2) and DAS28 (II) 3.09 (IQR = 1.7), p = 0.3; DAS (I) 2.09 (IQR = 1.6) and DAS (II) 2.03 (IQR = 1), p = 0.39; HAQ-DI (I) 0.44 (IQR = 0.57) and HAQ-DI (II) (IQR = 0.62), p = 0.32; BASDAI (I) 3.6 (IQR = 3.45) and BASDAI (II) 4.75 (IQR = 3.275), p = 0.46; BASFI (I) 1.9 (3.15) and BASFI (II) 1.1 (IQR = 1.2), p = 0.057; SF-36 physical health (I) 40.4 (IQR = 9.5) and SF-36 physical health (II) 38.7 (IQR = 11), p = 0.02; SF-36 mental health (I) 50.1 (IQR = 27) and SF-36 mental health (II) 50.9 (IQR = 14.2), p = 0.6.

Conclusions Accordingly to the results, increased values of disease activity indices (usually used in adults patients with RA and SpA) show that tendons as well as peripheral joints are involved in the inflammatory process of JIA polyarticular form. Therefore the evaluation of tendons/entheses in adult patients with JIA polyarticular form should be performed routinely in daily rheumatological practise including radiological assessment as well as standard evaluation of peripheral joints. Our data suggest that there is a necessity to create complex index which includes assessment of tendons/entheses/peripheral joints for patients with JIA.