Low starting dosage of infliximab with possible escalating dosage in psoriatic arthritis gives the same treatment results as standard dosage of adalimumab or etanercept: results from the nationwide Icelandic ICEBIO registry.

Objective: To explore differences in response to a low dosage regimen of infliximab with an escalating dosage in comparison to a standard dosage of etanercept and adalimumab in patients with psoriatic arthritis (PsA).

Methods: Biologically naïve PsA patients who were beginning anti-TNF-α therapy were selected from the ICEBIO registry. Demographics and clinical differences were compared in four treatment groups: infliximab <4 mg/kg; infliximab >4 mg/kg; etanercept or adalimumab at baseline and on follow-up (6 and 12 months, last visit). The Kruskal-Wallis rank sum test was used for comparison of the groups and the Wilcoxon test to compare the two infliximab dosage regimens.

Results: One hundred and eighty-five patients (61% female) were identified; 84 patients received infliximab, 66 etanercept, and 35 adalimumab. A total of 19% of the patients treated with infliximab escalated their dosage ≥4 mg/kg. No significant differences were observed at baseline in respect to visual analog scale (VAS) pain, VAS fatigue, Health Assessment Questionnaire, C-reactive protein (CRP), numbers of swollen or tender joints, or Disease Activity Score (DAS) 28-CRP values. A similar treatment response was observed in all four treatment groups on follow-up.

Conclusion: In respect to treatment effects, a low dosage of infliximab with possible escalating dosage is acceptable for the majority of PsA patients who are in need of biological treatment.