We assessed the efficacy, tolerance and cost of a 3mg/kg starting dose of infliximab for ankylosing spondylitis (AS) and psoriatic arthritis (PsA).

We retrospectively followed-up 45 biologic-naive consecutive patients (11 with axial AS, 24 with axial and peripheral [mixed] AS and 10 with PsA) who were treated between 2002 and 2005 with a 3mg/kg dose of infliximab after failure of conventional therapies. The following variables were recorded: visual analog scale (VAS) scores of patient’s global (G) and pain (P) assessment, duration of early morning stiffness (EMS), disease activity (BASDAI) and functional disability (BASFI). Treatment responses were assessed at 6 and 12 months using the AS assessment score (ASAS)-20% and -40% criteria and BASDAI-50.

Baseline characteristics of the 29 men and 16 women were (median [range]): G-VAS, 70 [13–100]; P-VAS, 70 [13–100]; EMS, 60 [0–180] minutes; BASDAI, 64.4 [23.9–100]; BASFI, 57.2 [3.5–98.5]. All manifestations regressed significantly (p<0.0001) for 39 (86.7%) and 24 (53.5%) patients at 6 and 12 months, respectively; 26 (57.8%) had achieved ASAS-20 responses at 6 months that persisted at 1 year for 20 (44.4%); 19 (42.2%) and 12 (26.7%) satisfied BASDAI 50 criteria at 6 and 12 months, respectively. Interestingly, almost 30% still received low-dose infliximab after 4 years of follow-up.

An initial dose of 3mg/kg of infliximab significantly attenuated AS and PsA manifestations in>40% of the patients, making use of this dose highly advantageous in terms of safety and 33% lower cost.