Mechanisms underlying DMARD inefficacy in difficult-to-treat rheumatoid arthritis: a narrative review with systematic literature search.

Management of RA patients has significantly improved over the past decades. However, a substantial proportion of patients is difficult-to-treat (D2T), remaining symptomatic after failing biological and/or targeted synthetic DMARDs. Multiple factors can contribute to D2T RA, including treatment non-adherence, comorbidities and co-existing mimicking diseases (e.g. fibromyalgia). Additionally, currently available biological and/or targeted synthetic DMARDs may be truly ineffective ('true' refractory RA) and/or lead to unacceptable side effects. In this narrative review based on a systematic literature search, an overview of underlying (immune) mechanisms is presented. Potential scenarios are discussed including the influence of different levels of gene expression and clinical characteristics. Although the exact underlying mechanisms remain largely unknown, the heterogeneity between individual patients supports the assumption that D2T RA is a syndrome involving different pathogenic mechanisms.

Difficult-to-treat rheumatoid arthritis: an area of unmet clinical need.

Increased effectiveness of pharmacological treatments in early RA has led many to believe that difficult-to-treat, established RA is a condition of the past. However, there are still plenty of RA patients who continue to have signs and symptoms suggestive of inflammatory disease activity, despite consecutive treatment with multiple conventional synthetic and biological DMARDs. We argue that difficult-to-treat RA constitutes an area of unmet clinical need and propose a definition of this concept. An overview of what is known about the multiple contributory factors varying for each individual patient, and an approach towards improved patient-tailored management are presented. This management approach involves thorough assessment to determine whether persistence of signs and symptoms is based on inflammatory disease activity, and the role of comorbidities. Furthermore, it addresses medication-related issues, such as non-adherence, patient beliefs and expectations, and setting of realistic treatment goals.