TNF and spondylitis: Different predictors of a favourable response to the first anti-TNF drug have been reported in the literature, including shorter disease duration, younger age, HLA-B27 positivity, a lower Bath Ankylosing Spondylitis Functional Index score, higher C-reactive protein levels, a higher Bath Ankylosing Disease Activity Index score, male sex and the presence of peripheral arthritis and spinal inflammation on magnetic resonance imaging [18,32-39].