Does vit D level predict response to RA Rx? Yes...maybe! POS0100 showed in 236 RA pts, 57% starting TNFi, rest other bDMARDs, at 1 yr, good responders & remission 4x less likely to respond if low vit D but sig for DAS(ESR) not CDAI/SDAI. ?Give VIT D to all! #EULAR2021 @RheumNow