Patients with < 4 years and 4 years of disease were compared for improvement in Bath Ankylosing Spondylitis Disease Activity Index ( BASDAI ) , Bath Ankylosing Spondylitis Functional Index ( BASFI ) , Ankylosing Spondylitis Disease Activity Score ( ASDAS ) , C-reactive protein ( CRP ) and magnetic resonance imaging ( MRI ) score for sacroiliac joints ( SIJ ) .