Rheumatoid arthritis monotherapy in the Jak inhibitors Era. Current prevalence and associated factors in a multicenter study.

Background: Combined therapy constitutes the standard of care in RA. Jak inhibitors (Jaki) have shown efficacy in monotherapy, a modality used in cases where it is not possible to use Disease-Modifying Anti Rheumatic Drugs (csDMARDs).

Objectives: To estimate the prevalence (total and by drug), reason for using and the increase over the time of bDMARDs or tsDMARDs as monotherapy after the availability of the Jaki. To analyze the differential characteristics between patients with monotherapy vs combined therapy.

Methods: Cross-sectional multicenter study. Consecutive patients with a diagnosis of RA (ACR/EULAR 2010) under treatment with bDMARDs or tsDMARDs started from 2013 were included. Socio-demographic, clinic, and therapeutic data were collected.

Results: A total of 505 RA patients were included. Since 2013, the prevalence of monotherapy usage was (any) 49%. The drugs used as monotherapy were Jaki in 41% and TNF-blockers in 30%. The leading causes of monotherapy use were intolerance/adverse events (62%), medical decision or lack of adherence (37.7%). The highest socioeconomic level and a better functional status at diagnosis were predictors of monotherapy use. The use of the second line of treatments and less polypharmacy were independent factors associated with this therapeutic modality.

Conclusions: The current prevalence of monotherapy in RA was 49%, the Jaki were the most used drug in this modality. Monotherapy increases from year to year. There are differential characteristics in patients using monotherapy.