Tumour necrosis factor inhibitor survival and predictors of response in axial spondyloarthritis—findings from a United Kingdom cohort by Yahya, Fariz, Gaffney, Karl, Hamilton, Louise, Lonsdale, Ellie, Leeder, Jane, Brooksby, Alan, Cavill, Charlotte, Berry-Jenkins, Joshua, Boyle, Cathal, Bond, Debbie, Sengupta, Raj