Objectives To describe disease activity 30 years after disease onset in a previously studied cohort of patients with juvenile idiopathic arthritis (JIA) and reveal predictors of long-term active disease.

Methods Patients with JIA, first referred 1980–1985 and re-examined 15 and 23 years after onset, were invited to attend. All 176 patients were assessed by questionnaires. Patients with signs of active disease at 15 years or later also came to a clinical re-examination (n=90). Disease activity was assessed by the clinical juvenile arthritis disease activity score (JADAS3) and by the criteria for remission in JIA, and health status by Health Assessment Questionnaire (HAQ) and Medical Outcome Study 36-item Short Form Health Survey (SF-36).

Results At 30-year follow-up, 59% of the patients were in clinical remission off medication, 7% were in remission on medication and 34% had active disease. 70% of the patients were in the same category of disease activity at 15 and 30 years. The JADAS3 was ≤2.0 in 54%, 2.1–4.5 in 18% and >4.5 in 28%. HLA-DRB1*01, physician's global assessment and a short total time in remission at 15 years, predicted active disease. Physician's global assessment also predicted a JADAS3 >4.5. From 15 to 30 years (n=90), physician's global assessment, number of active joints, erythrocyte sedimentation rate and C reactive protein improved significantly, but patient's global assessment, HAQ and SF-36 did not.

Conclusions 41% of the patients with JIA had active disease or were on medication after 30 years and 28% had a high symptom state. Remission rates and patient-reported health status at 15 years were comparable with rates at 30 years.