Objectives To compare effectiveness, safety and costs of standard versus individually tailored reduced doses of anti-TNF drugs in patients with Ankylosing Spondylitis (AS) after achieving low disease activity.

Methods This was a single center prospective observational study performed within the national biologics registry. The anti-TNF dose tapering strategy was chosen by treating physicians, without pre-specified protocol. We used propensity score (PS) methodology to identify 2 cohorts of patients matched for relevant baseline characteristics (age, gender, baseline activity, baseline function, disease duration, duration of anti-TNF therapy - see table) who were treated with either reduced (n=53) or standard (n=83) doses of TNF inhibitors. Two years outcomes and costs of anti-TNF drugs were compared between both PS-matched cohorts.

Results In the reduced dosing group the median dose of TNF inhibitor corresponded to 0.67, and 0.58 of the standard dose initially, and at 24 months resp., and 23% of patients required return to standard dosing regimen. The hazard ratio (95% CI) of reduced versus standard dosing group for relapse and any adverse event was 1.25 (0.68; 2.28), and 0.61 (0.31; 1.19) resp. (Figure). The mean change per 2 years in BASFI, as well as BASDAI and CRP area under the curve (AUC) were no different between both groups, but the cost for anti-TNF drugs was substantially lower in the reduced dosing group (table).

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Conclusions In AS patients after reaching low disease activity a tailored approach to reduce doses of anti-TNF drugs produced similar clinical outcomes at 2 years, but was substantially less costly.

Acknowledgements Supported by project of MHCR for conceptual development of research organization 023728

Disclosure of Interest None declared