Causes of the Failure of Biological Therapy at a Tertiary Center: A Cross-Sectional Retrospective Study.

Introduction Rheumatoid arthritis (RA) is one of the most commonly encountered autoimmune diseases. Treatment generally includes disease-modifying anti-rheumatic drugs (DMARDs) and/or biological therapy. However, a significant proportion of the patients do not respond to treatment either as a (primary failure) or lose efficacy over time (secondary failure).