Predictors of response and drug survival in ankylosing spondylitis patients treated with infliximab

BACKGROUND: The advent of anti-tumor necrosis factor-α (TNFα) drugs has changed the course of ankylosing spondylitis (AS). While data are available concerning the long term effectiveness of single anti-TNF agents, little has been published about predictors of treatment response in AS. The aim of this retrospective study was to evaluate the survival, effectiveness, and safety of infliximab over a 5-year period and to identify predictors of disease outcome. METHODS: Seventy AS patients attending the Rheumatology Clinic of the University of Padua who were treated with intravenous infliximab at 0, 2, 4 weeks and then every 6, 8, or up to 16 weeks were studied retrospectively. Demographic information, laboratory inflammatory and disease indices (BASDAI, BASFI, BASMI) were collected (at baseline, 3, 6, 12 months and once a year thereafter). Clinical improvement, drug tolerability, adverse events/side effects and causes leading to discontinuation were recorded. RESULTS: Infliximab caused a rapid, persistent improvement at all the assessment times in the BASDAI 50 (71.4 %) and ASDAS scores (97.1 % in ASAS20, 80 % in ASAS40, 80 % in ASAS5/6), and already within 6 months of beginning treatment in 50 % percent of the patients. The other 50 % withdrew because of: adverse events (12 = 34.3 %), side effects (5 = 14.3 %), drug inefficacy (12 = 34.3 %), spontaneously (4 = 11.4 %). Those who did not respond were prevalently females (34.3 % vs 17.1 %). CONCLUSION: Factors such as female sex, use of steroids, persistently high inflammatory levels, BASFI and BASDAI indices were found to be negative predictors of treatment response. Infliximab was found to be safe, effective and well-tolerated; it elicited satisfactory long term response and drug survival rates.