Predictive value of serum amyloid a levels for requirement of concomitant methotrexate in tocilizumab initiation: A <i>post hoc</i> analysis of the SURPRISE study

<b>Objectives:</b> To identify predictive factors for remission by tocilizumab monotherapy in rheumatoid arthritis (RA) patients. <b>Methods:</b> This is a <i>post hoc</i> analysis of the SURPRISE study, a 2-year randomized, controlled study comparing the efficacy of tocilizumab with (ADD-ON) and without methotrexate (SWITCH). The primary endpoint was DAS28-ESR remission (&lt;2.6) at week 24. The change in modified total Sharp score from baseline to week 52 (ΔmTSS/year) was also assessed as an endpoint. The effect of clinical parameters at baseline on remission was estimated by logistic regression analysis. <b>Results:</b> In SWITCH (<i>n</i> = 96), CRP, SAA, RF, and DAS28 at baseline showed predictive value for DAS28 remission in unadjusted analysis. Adjusted analysis confirmed SAA and DAS28 as predictive factors, with SAA having the highest value (ROC-AUC = 0.731). Furthermore, structural remission (ΔmTSS/year ≤ 0.5) rate was significantly higher in patients with SAA of n = 98), only DAS28 showed predictive value for DAS28 remission. In patients with SAA <b>Conclusion:</b> RA patients with low SAA levels at baseline may benefit similarly from tocilizumab with and without methotrexate. <b>Trial registration number:</b> NCT01120366.