To evaluate the role of MRI in predicting a Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) improvement of at least 50% (BASDAI 50) upon anti-tumour necrosis factor (TNF) therapy of active ankylosing spondylitis (AS).
MRIs from patients with active AS who participated in randomised controlled trials were analysed with respect to presence and extent of active inflammatory lesions as detected in the spine (n = 46), sacroiliac (SI) joints (n = 42) and both sites (n = 26). Univariate and multivariate logistic regression analyses were applied to evaluate MRI and clinical data in predicting a BASDAI 50 response.
The Berlin MRI spine score (odds ratio (OR) 1.16, 95% CI 1.02 to 1.33) and disease duration (OR 0.9, 95% CI 0.63 to 0.97) were statistically significant predictors of a BASDAI 50 response using regression analysis while there was only a trend for C-reactive protein (CRP). The likelihood ratio (LR) for achievement of BASDAI 50 was increased in patients with a Berlin MRI spine score >/=11 (LR 6.7), disease duration <10 years (LR 4.2) and CRP >/=40 mg/litre (LR 3.4). All patients with two or three of these predictors improved clinically (as assessed by BASDAI) by at least 45%. Disease duration >20 years, normal CRP and no active inflammatory lesion in the spine were highly predictive of not achieving BASDAI 50. A trend was only found for the MRI score of SI joints to be predictive.
Widespread inflammation in the spine as detected by MRI contributes to predicting a BASDAI 50 response in active patients with AS treated with anti-TNF agents.