SPARCC spine scores correlated with baseline symptom duration , and SI joint scores correlated negatively with the baseline Bath Ankylosing Spondylitis Disease Activity Index , but neither correlated with the baseline Ankylosing Spondylitis Disease Activity Score , total back pain , the patient 's global assessment of disease activity , the Bath Ankylosing Spondylitis Functional Index , morning stiffness , nocturnal pain , or C-reactive protein level .