Does height influence the assessment of spinal and hip mobility measures used in ankylosing spondylitis?

OBJECTIVE: It is not known if height contributes to the variability in mobility measures in patients with ankylosing spondylitis (AS) and whether any measures should be reported corrected for height. We examined the contribution of height to the variability of mobility measures in patients with a diverse spectrum of AS disease. METHODS: We assessed the 9 mobility measures comprising the Bath AS and Edmonton AS Metrology Indices (BASMI and EDASMI) in a total of 205 patients. The contribution of height to the variability in mobility scores was analyzed descriptively according to tertiles of height, and also by combined probability scatter plots that combined each individual's height with the corresponding score for either the composite index or each of the 9 spinal mobility measures. Hierarchical (sequential) linear regression was used to assess the contribution of height to the variance in EDASMI and BASMI composite scores and individual measures, adjusted for age, disease duration, and the Bath AS Disease Activity Index. RESULTS: Descriptive data and correlation analysis revealed significant differences related to height for both the EDASMI and the BASMI, particularly for EDASMI cervical rotation, EDASMI lumbar side flexion, chest expansion, lumbar flexion, and intermalleolar distance. Combined probability scatter plots showed that for a particular height there was a wide distribution of mobility scores and only intermalleolar distance showed some relation to height. Hierarchical regression analysis showed that height contributed significantly, although relatively minimally to the variance of both the EDASMI (3.1%; p

Development and validation of the Edmonton Ankylosing Spondylitis Metrology Index.

OBJECTIVE: Assessment of spinal and hip mobility has been recommended by the Assessments in Ankylosing Spondylitis (AS) Working Group for clinical trials and record keeping, although suggested measures primarily reflect structural damage. Our objective was to validate a simple, 4-item composite measure of spinal and hip mobility, the Edmonton AS Metrology Index (EDASMI). METHODS: We assessed the EDASMI and the Bath AS Metrology Index (BASMI) using a total of 263 patients from 3 countries: Canada (n = 205), Australia (n = 29), and Colombia (n = 29). Intra- and interobserver reliability were assessed in a subset of 44 patients. Construct validity with respect to disease activity (Bath AS Disease Activity Index [BASDAI]), function (Bath AS Functional Index [BASFI]), and structural damage (modified Stoke AS Spinal Score [mSASSS]) was analyzed using correlation and hierarchical regression. Responsiveness was assessed in a subset of 33 patients who received either anti-tumor necrosis factor alpha therapy (n = 26) or pamidronate (n = 7) over 24 weeks. RESULTS: In contrast to the EDASMI, BASMI scores covered a limited range, with 70% of patients demonstrating a score < or =3 (range 0-10) and 4 of 5 individual measures demonstrating substantial floor effects. Both measures were highly reliable (intraclass correlation coefficient >0.90) and demonstrated similar construct validity (EDASMI correlated with disease duration [0.52], BASDAI [0.24], BASFI [0.61], Bath Ankylosing Spondylitis Radiology Index [0.79], mSASSS [0.75]; P < 0.001 for all). The change in EDASMI score was significant after 24 weeks of therapy (standardized response mean 0.40; P = 0.03), but change in the BASMI was not significant. CONCLUSION: The EDASMI is a simple, rapid, and reliable tool for the assessment of spinal mobility in AS that is responsive to therapeutic intervention.

Infliximab in ankylosing spondylitis: a prospective observational inception cohort analysis of efficacy and safety.

OBJECTIVE: Infliximab, a neutralizing antibody to tumor necrosis factor-alpha, appears to be effective therapy in ankylosing spondylitis (AS), although treatment is costly and serious infections are an increasing concern. We investigated the efficacy and tolerability of infliximab in a prospective observational inception cohort of patients with nonsteroidal antiinflammatory drug-refractory AS seen in both university and community based practice. We also used a lower dose, 3 mg/kg, than has been evaluated to date in AS. METHODS: We included all consecutive patients with AS starting infliximab therapy 3 mg/kg i.v. at 0, 2, and 6 weeks and q 2 months between April 2000 and October 2001. Data were systematically collected at baseline, 14 weeks, and 1 year, or at withdrawal, and included demographic characteristics, Bath AS indexes (BASDAI, BASFI, BASGI, BASMI), adverse events, and reasons for withdrawal. Laboratory measures included erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), serum matrix metalloproteinases (MMP) 1 and 3, and serum human cartilage glycoprotein-39 (YLK-40). The first 6 consecutive patients were also studied by several magnetic resonance sequences, including dynamic MRI with gadolinium augmentation of affected joints. Maximal rate of augmentation was determined at baseline and 84 days. Analysis was by intention-to-treat. RESULTS: Twenty-one patients (m:f = 17:4), mean age 42.5 years (range 24-66), mean disease duration 13.8 years (range 3-26), were studied: 13 had active peripheral synovitis at baseline. Mean followup was 47.5 weeks (range 10-77). Four patients withdrew, 2 for serious adverse events (septic osteomyelitis and severe hypersensitivity after 3 and 2 infusions, respectively), one for lack of efficacy, and one lost to followup. Three patients required an increased dose to 5 mg/kg after 14 weeks. Efficacy data were available on 17 patients at 14 weeks; mean BASDAI improved significantly from baseline (6.2) to 14 weeks (2.8) (p < 0.001), with 10 patients (58.8%) showing at least 50% improvement (range 0-99.6%). Significant reduction in mean BASFI (43.4%; p < 0.001), BASGI (44%; p = 0.001), ESR (55%; p < 0.001), and CRP (63.5%; p = 0.01) was evident. Complete remission of peripheral joint disease was seen in 5 of 11 (45.4%) patients evaluated at 14 weeks and maximal rate of MRI defined gadolinium augmentation was significantly decreased (p = 0.04). Reductions in serum YKL-40 and MMP-1 and 3 were nonsignificant, but significant correlations were observed between changes in BASDAI, ESR, CRP, and changes in serum levels of MMP-3 and YKL-40 (p < 0.005 to p < 0.05). Followup data on 8 patients completing 1 year of therapy revealed continued efficacy at a dose of 3 mg/kg every 8 weeks. CONCLUSION: Infliximab appears to be effective and well tolerated for both axial and peripheral joint disease in AS even at lower doses than those examined to date. Suppression of markers of cartilage degradation/turnover commensurate with reductions in clinical and laboratory measures of disease activity suggests that these markers should be further validated as surrogates for structural damage in AS. Controlled trials are warranted to further assess the potential of this agent in ameliorating structural damage.