Objective: To assess, firstly, the validity of the enthesis index published by Mander (Mander enthesis index (MEI)) and, secondly, to investigate whether it is possible to define a new enthesis index that is less time consuming to perform with at least similar or better properties. Methods: Data from the OASIS cohort, an international, longitudinal, observational study on outcome in ankylosing spondylitis, were used. In this study, measures of disease activity, including the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and the MEI, were assessed regularly in 217 patients. With the MEI, for each measurement period independently, a process of data reduction was performed to identify the entheses most commonly reported as painful by the patients. A more concise enthesis index was constructed with aid of the entheses found in this way. Correlations with measures of disease activity were used to test the validity of several entheses indices. Results: Reduction of the number of entheses from 66 to 13 and omitting grading of the intensity of pain resulted in an index which was named the "Maastricht Ankylosing Spondylitis Enthesitis Score" (MASES). The MASES (range 0-13) has much greater feasibility than the MEI (range 0-90). However, up to 21% of patients with a score >0 on the MEI were not identified by a score on the MASES >0. Only 2.1% of the patients with an original enthesis score >0 had an original score on the MEI >3 (range 0-90) and it can be questioned whether a low score on the MEI index represents clinically important enthesitis. The Spearman correlation coefficient between the MASES score and the MEI was 0.90 and between the MASES and the BASDAI was 0.53 compared with a correlation of 0.59 between the MEI and the BASDAI. Conclusions: MASES seems to be a good alternative to the MEI with much better feasibility.

IntroductionIdentifying ankylosing spondylitis (AS) patients who are likely to benefit from tumor necrosis factor-alpha (TNF-α) blocking therapy is important, especially in view of the costs and potential side effects of these agents. Recently, the AS Disease Activity Score (ASDAS) has been developed to assess both subjective and objective aspects of AS disease activity. However, data about the predictive value of the ASDAS with respect to clinical response to TNF-α blocking therapy are lacking. The aim of the present study was to identify baseline predictors of response and discontinuation of TNF-α blocking therapy in AS patients in daily clinical practice.MethodsAS outpatients who started TNF-α blocking therapy were included in the Groningen Leeuwarden Ankylosing Spondylitis (GLAS) study, an ongoing prospective longitudinal observational cohort study with follow-up visits according to a fixed protocol. For the present analysis, patients were excluded if they had previously received anti-TNF-α treatment. Predictor analyses of response and treatment discontinuation were performed using logistic and Cox regression models, respectively.ResultsBetween November 2004 and April 2010, 220 patients started treatment with infliximab (n = 32), etanercept (n = 137), or adalimumab (n = 51). At three and six months, 68% and 63% of patients were Assessments in Ankylosing Spondylitis (ASAS)20 responders, 49% and 46% ASAS40 responders, and 49% and 50% Bath Ankylosing Spondylitis Disease Activity Index (BASDAI)50 responders, respectively. Baseline predictors of response were younger age, male gender, higher ASDAS score, higher erythrocyte sedimentation rate (ESR) level, higher C-reactive protein (CRP) level, presence of peripheral arthritis, higher patient's global assessment of disease activity, and lower modified Schober test. In August 2010, 64% of patients were still using their TNF-α blocking agent with a median follow-up of 33.1 months (range 2.4 to 68.2). Baseline predictors of discontinuation of TNF-α blocking therapy were female gender, absence of peripheral arthritis, higher BASDAI, lower ESR level, and lower CRP level.ConclusionsBesides younger age and male gender, objective variables such as higher inflammatory markers or ASDAS score were identified as independent baseline predictors of response and/or continuation of TNF-α blocking therapy. In contrast, higher baseline BASDAI score was independently associated with treatment discontinuation. Based on these results, it seems clinically relevant to include more objective variables in the evaluation of anti-TNF-α treatment.

Objectives. To investigate whether the single-item fatigue question of the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and the Multidimensional Fatigue Inventory (MFI) are appropriate instruments to measure fatigue in ankylosing spondylitis (AS); to identify factors that influence fatigue in AS; and to assess how fatigue in all its aspects is associated with quality of life in AS. Methods. A total of 812 patients with AS were included. Patients completed questionnaires on disease activity (BASDAI), functional ability (Bath Ankylosing Spondylitis Functional Index [BASFI]), global well-being (Bath Ankylosing Spondylitis Global Score [BAS-G]), overall perceived health (EuroQoL visual analog scale), and quality of life (Ankylosing Spondylitis Quality of Life questionnaire, and Short Form 36 [SF-36]).Patients were dichotomized into a F؉ group (fatigue ‫؍‬ major symptom) if the BASDAI fatigue score was > 5.0 and a F؊ group (fatigue ‫؍‬ minor symptom) if the fatigue score was < 5.0. Reproducibility was assessed with intraclass correlation coefficients, and responsiveness was calculated according to 3 different methods. Logistic regression analysis was used to determine which factors were associated with fatigue. Multiple regression analysis was used to investigate whether fatigue contributes in explaining quality of life. Results. Fifty-three percent of the patients were assigned to the F؉ group. They scored significantly worse compared with the F؊ group with respect to each dimension of the MFI and to all other questionnaires studied (all P < 0.001). The BASDAI fatigue question, as well as each separate dimension of the MFI, showed moderate to good reproducibility (0.57-0.75) and responsiveness (0.23-0.96). Fatigue was, in the opinion of the patients, highly associated with pain (70% of patients) and stiffness (54% of patients). Logistic regression analysis showed that scores on BASDAI, BASFI, BAS-G, and mental health status (SF-36) were independently associated with fatigue (R 2 ‫؍‬ 0.52). Multiple regression analysis showed that scores on the BASDAI fatigue question were significantly associated with quality of life. With the 5 MFI dimensions as explanatory variables, different aspects of fatigue were associated with different domains of quality of life. Conclusion. Fatigue as a major symptom of AS can effectively be measured with either a single-item question on the intensity of fatigue or with the MFI. The MFI, however, provides more insight into specific dimensions of fatigue. Fatigue appears to be associated with the level of disease activity, functional ability, global well-being, and mental health status. In addition, fatigue negatively influences different aspects of quality of life. KEY WORDS. Fatigue; Ankylosing spondylitis; Questionnaires; Quality of life; Assessment. INTRODUCTIONFatigue has been acknowledged as an important symptom in ankylosing spondylitis (AS) (1-4). Although fatigue is a widely used term, no uniformly accepted definition is available. Belza described fatigue as "the end...

IntroductionThe aim of this study was to investigate the construct validity and test-retest reliability of the International Physical Activity Questionnaire (IPAQ; long form) and the Short QUestionnaire to Assess Health-enhancing physical activity (SQUASH) and to investigate the relation between daily physical activity and clinical assessments in patients with ankylosing spondylitis (AS).MethodsFor validity, the self-report questionnaires IPAQ and SQUASH were compared with daily physical activity assessed with the ActiGraph accelerometer during 7 consecutive days in 63 AS outpatients. For reliability, the IPAQ and SQUASH were administered twice approximately 1 week apart in 52 AS outpatients. In all 115 patients, clinical assessments were performed at the outpatient clinic.ResultsIPAQ and SQUASH total scores correlated significantly with accelerometer outcome: ρ = 0.38 and r = 0.35, respectively. Intraclass correlation coefficients between first and second assessments of the IPAQ and SQUASH were 0.83 and 0.89, respectively. Bland-Altman analyses showed no systemic bias, but in particular for the IPAQ the 95% limits of agreement were wide. Daily physical activity assessed by accelerometer, IPAQ, and SQUASH correlated significantly with disease activity, physical activity, and quality of life. A relation with spinal mobility was found only for the accelerometer and SQUASH. The direction of these correlations indicates that higher daily physical activity is related to lower disease activity and better physical function, spinal mobility and quality of life.ConclusionsBoth physical activity questionnaires showed modest construct validity. The SQUASH showed good test-retest reliability, superior to the IPAQ. These results indicate that the SQUASH is more suitable than the IPAQ to assess daily physical activity in AS population studies. However, it is desirable to add questions on AS-specific physical activity. Further studies are needed to investigate the causality of the relation between daily physical activity and clinical assessments.