Background Inflammatory entheseal and hip involvement are characteristic extra-spinal manifestations of ankylosing spondylitis (AS). In clinical studies these manifestations are commonly evaluated by enthesitis indexes such as the Maastricht AS Enthesitis Score (MASES) and by standardized power Doppler ultrasound (PDUS) of multiple entheseal sites.
Objectives To evaluate inflammatory PDUS lesions of the entheses and hip joints in patients with AS before and after 6 months of tumor necrosis factor-alpha (TNF-α) blocking therapy in daily clinical practice.
Methods Between November 2004 en October 2008, consecutive outpatients from the Groningen Leeuwarden AS (GLAS) cohort with available PDUS examination before and after 6 months of TNF-α blocking therapy were included in this analysis. All patients fulfilled the modified New York criteria for AS and started TNF-α blocking therapy because of active disease according to the international criteria. Disease activity was assessed with the Bath AS disease activity index (BASDAI) and AS disease activity index (ASDAS). Clinical evaluation of enthesitis was performed with the MASES (range 0-13). PDUS examination was performed at the hip joint and 9 bilateral entheses: plantar fascia, Achilles tendon, tibialis anterior, patellar tendon, quadriceps femoris, pes anserinus, trochanter major, lateral and medial epicondyle of the elbow. Inflammatory lesions assessed at each entheseal site were hypo-echogenicity, thickening, adjacent bursitis and effusion in B-mode as well as positive power Doppler (PD) signal.
Results Mean age of the 85 included AS patients was 43 years (SD ±10.5), median symptom duration 17 years (range 2-49), 73% were male, 85% HLA-B27 positive and 26% had a history of reported hip involvement. Median BASDAI, ASDAS and MASES before start of TNF-α blocking therapy were 5.8, 3.8 and 2, respectively, and improved significantly after 6 months of treatment to 2.6, 1.8 and 1, respectively (p<0.001).
At baseline, 18 patients (21%) showed ≥1 inflammatory lesion of the hip joints with PDUS, which decreased significantly to 6 patients (7%) after 6 months of treatment (p<0.01). Of these patients, positive PD signal of the hip joints decreased significantly from 14 patients (17%) at baseline to 5 patients (6%) after 6 months (p<0.01). In contrast, 67 patients (81%) showed ≥1 inflammatory entheseal lesion with PDUS before start of TNF-α blocking therapy, for which no significant decrease could be found after 6 months of treatment. Also no decrease in positive PD signal was observed for the entheseal sites.
Conclusions This prospective observational cohort study in daily clinical practice shows substantial inflammatory PDUS hip and entheseal lesions in AS patients before start of TNF-α blocking therapy. In the evaluation of the response to TNF-α blocking therapy, only inflammatory PDUS lesions of the hip joints decreased significantly.
Acknowledgements The GLAS cohort was supported by an unrestricted grant from Pfizer. Pfizer had no role in the design, conduct, interpretation, or publication of this study.
Disclosure of Interest F. Wink: None declared, G. Bruijn: None declared, E. Van der Veer: None declared, H. Bootsma: None declared, E. Brouwer Grant/research support: Abbott, Pfizer, Wyeth, S. Arends Grant/research support: Abbott, Pfizer, Wyeth, A. Spoorenberg Grant/research support: Abbott, Pfizer, Wyeth, Consultant for: Abbvie, Pfizer, UCB