Background. To assign genetically engineered biologic drugs, we need data on the predictors for response to therapy. Prognostic factors for the response to tocilizumab in patients with juvenile idiopathic arthritis (JIA) without systemic symptoms are poorly studied.

Objective. Our aim was to reveal early predictors for the response to tocilizumab therapy in patients with JIA without systemic symptoms.

Methods. A retrospective cohort study enrolled patients with JIA without systemic symptoms who received tocilizumab therapy between July 2009 and August 2017. We assessed the association between the initial demographic, clinical, and laboratory parameters in patients and the best response (according to the ACR90 criteria) to treatment after a year.

Results. The study included 95 (girls 85%) patients; the mean age was 10.3 (6.0; 13.6). During the first year of therapy, 71 (75%), 55 (58%), 38 (40%), and 22 (23%) patients achieved the improvement according to ACR30/50/70/90 criteria, respectively; 22 (23%) patients reached disease inactive stage according to the Wallace criteria. When performing multivariate analysis, the following improvement predictors were revealed based on the ACR90 criteria after a year of treatment: decrease in serum C-reactive protein level during the first month of therapy [odds ratio (OR) 1.024; 95% confidence interval (CI) 1.007–1.051], decrease in disease activity score on the visual analogue scale according to the parent/patient assessment (OR 1.048; 95% CI 1.005–1.105), early onset of the disease (OR 0.38; 95% CI 0.16–0.72), persistent oligoarthritis according to the ILAR (OR 9.9; 95% CI 1.5–109.3). During the first year of tocilizumab administration, neutropenia was registered in one patient, leukopenia — in three cases, and urticaria — in one case.

Conclusion. The variant of JIA, the age at the disease onset, and the disease course pattern in the first month of tocilizumab therapy are the predictors of treatment efficacy throughout the year.