Short-term response in new users of anti-TNF predicts long-term productivity and non-disability: analysis of Czech ATTRA ankylosing spondylitis biologic registry

<b>Objectives</b>: To assess the role of short-term response to first anti-TNF in long-term prediction of disability. <b>Methods</b>: In nationwide registry ATTRA, we identified ankylosing spondylitis patients starting anti-TNF between 01/2003 and 12/2016. Full disability and work impairment (WI; WPAI questionnaire) were predicted via the Cox- and lagged-parameter mixed-effect regression. <b>Results</b>: 2,274 biologicals-naïve patients newly indicated to anti-TNF were prospectively followed (6,333 patient-years; median follow-up 1.9 years). Reaching BASDAI <b>&lt;</b> 4 (77.4%) and ASDAS-CRP <b>&lt;</b> 2.1 (61.1%) after 3 months of anti-TNF both decreased the risk of future disability by ≈2.5-fold. ASDAS-CRP <b>&lt;</b> 2.1 predicted non-disability better than BASDAI <b>&lt;</b> 4 &amp; CRP <b>&lt;</b> 5 mg/L (p = 0.032). BASDAI <b>&lt;</b> 4 &amp; CRP <b>&lt;</b> 5 mg/L was comparable to BASDAI <b>&lt;</b> 4 (p = 0.941) and to BASDAI change by &gt;50% or by &gt;2 points (p = 0.902). ASDAS-CRP change &gt;1.1 and &gt;2.0 both failed to predict non-disability. Once on anti-TNF therapy, the strongest predictor of WI was Pain (SF36). Yearly increase in indirect costs remains below €3,000 in those reaching ASDAS-CRP <b>&lt;</b> 2.1. <b>Conclusions</b>: Low disease activity measured by ASDAS-CRP ≤ 2.1 should be used to measure the outcome of new anti-TNF therapy. Continuous WI could be decreased through pain management.