May We Use Enthesitis Indices in Evaluating Disease Activity in Patients with Ankylosing Spondylitis?

Aims: The objective of the present study was to investigate the parameters related to disease activity in patients with Ankylosing Spondylitis (AS). Materials and methods: Fifty-three patients with AS who fulfilled the modified New York criteria were included in this study. The demographic data of the patients were recorded. Laboratory evaluation of the patients comprised erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). Disease activity was assessed using Bath Ankylosing Spondylitis Disease Activity Index (BASDAI). Functional disability was evaluated using The Bath Ankylosing Spondylitis Functional Index (BASFI) and Dougados Functional Index (DFI). Clinical status was evaluated with Bath Ankylosing Spondylitis Metrology Index (BASMI) and quality of life was assessed with Ankylosing Spondylitis Quality of Life Scale (ASQoL). We assessed enthesitis by two indices: Mander Enthesitis Index (MEI) and Maastricht Ankylosing Spondylitis Enthesitis Score (MASES). Results: The patients were divided into two groups: patients having BASDAI scores of less than four (BASDAI<4) with mild disease activity (N=42) and patients having BASDAI scores of four or higher (BASDAI≥4) with moderate to severe disease activity (N=11). MEI, MASES and BASFI scores were significantly higher in patients with moderate to severe disease activity. No significant difference was found in terms of CRP, BASMI and ASQoL between the two groups. A significant correlation was found between the BASDAI scores and MEI, MASES, CRP, DFI and BASFI in patients with AS (the correlation coefficients were 0.538, 0.544, 0.328, 0.407 and 0.466 respectively. P values were <0.05 for all). Conclusions: Laboratory findings are not enough to evaluate disease activity in AS. However CRP seems to have better correlation with disease activity than ESR does and MASES and MEI seem to be an appropriate surrogate for disease activity in AS patients.