Clinical and imaging correlates of response to treatment with infliximab in patients with ankylosing spondylitis

Objectives. Ankylosing spondylitis (AS) is a chronic disease leading to pro gressive spinal ankylosis and deformity. The aims of this study were to (1) determine whether infliximab is an effective treatment for AS patients who have failed conventional treatment; (2) identify any baseline clinical var iables that can be associated with responsiveness to treatment; and (3) res olve whether the clinical response correlated with changes from baseline in flammatory changes on magnetic resonance imaging (MRI). Methods. Twenty-one patients who met the modified New York criteria for AS (M:F 18:3) were enrolled in this open labeled study. The mean age was 37.9 +/- 7.9 years and mean disease duration was 8.69 +/- 6.58 years. Patients r eceived infliximab at a dose of 5 mg/kg by intravenous infusion over 2 hour s at 0, 2, 6, weeks. Nine functional variables were measured [i.e,, Bath AS Disease Activity Index (BASDAI), Bath AS Functional Index (BASFI) etc.], 6 clinimetrics (chest expansion, finger to floor, etc.), and inflammatory ma rkers in the peripheral blood at baseline and each subsequent visit. Primar y response to treatment was defined as a > 20% response in 5/9 functional v ariables. A subset of 9 consecutive patients was selected for MRI scans bef ore and after infusions, Results. Eighteen patients were available for assessment at week 14 having received 3 infusions (wks 0, 2, 6). There was > 60% improvement in function al variables, i.e., BASDAI, BASFl, Health Assessment Questionnaire, fatigue , and spinal and total body pain, Clinimetric scores selectively improved, e,g., chest expansion (p < 0.021) by 14 weeks. ESR, CRP and haptoglobin all showed significant improvement at 6 weeks and were maintained to the 14 we ek assessment point. Imaging studies showed improvement in all patients stu died including those with advanced disease. Three patients developed headac he during the infusions. Infliximab was effective in all, but degree of res ponse varied. Very good responders were distinguished from good responders by shorter duration of disease and better baseline clinimetric scores, Conclusions. Infliximab was an effective treatment for AS in a short term t rial. longterm control of symptoms and potential alteration in clinical cou rse of disease will require longterm assessment.