Abstract
OBJECTIVES: High biologic requirement in inflammatory rheumatic diseases (IRD) may indicate a difficult to treat (D2T) condition. In axial spondyloarthritis (axSpA), a consensual definition for this concept is still lacking. Our objectives are to identify the prevalence and characteristics of multiswitcher patients with axSpA, and to analyse the number and reasons for switches. METHODS: This is a longitudinal observational study including patients treated with biologic agents for axSpA. We propose to define D2T patients as those who required more than 2 b/tsDMARD. Patients who did not fulfil this definition were used as controls. The prevalence of multiswitchers was calculated, and characteristics were compared between the two groups. The number and reasons for switches were analysed in the D2T group. RESULTS: 124 patients were included. The prevalence of multiswitchers was 24.19%. There were no significant differences between the two groups in the age, sex, and comorbidities. D2T patients have more arthritis (p=0.01), and fibromyalgia (p=0.04), and higher disease activity before initiating biotherapy, (BASDAI:p=0.04), (ASDAS:p=0.04). Additionally, the time from diagnosis to the first use of biologic was longer (p=0.04). In the multivariate analysis, the D2T condition was found to be associated with fibromyalgia (p=0.01). Among this group, the prevalence of those treated with 3, 4, and 5 b/tsDMARD was 86%, 9%, and 5%, respectively, the primary and secondary failures were the most common reasons for switching. CONCLUSION: We suggest that D2T-axSpA present several characteristics. Identification of this category in large studies is necessary to establish a consensus definition.