Treatment decisions in axial spondyloarthritis daily clinical practice are more than treat-to-target.

OBJECTIVE: 'Treat-to-target principles' are advised for axial spondyloarthritis (axSpA), although a clear target is not yet defined and targets do not always reflect inflammation. Treat-to-target use and motives for treatment choices in clinics are unknown. Therefore, we studied the presence of residual disease activity according physician's opinion, patient's opinion and composite indices and compared them to the subsequent treatment decisions. METHODS: This cross-sectional multicentre study included 249 patients with a clinical diagnosis of axSpA ≥6 months. Remission and low disease activity according to the BASDAI (<1.9 and <3.5, respectively) and physician's and patient's opinion were assessed. Questionnaires included patient-reported outcomes and patients and physicians completed questions regarding treatment decisions. RESULTS: A total of 115/249 (46%) patients were in remission according to the physician and 37% (n = 43) of these patients reached remission according to the BASDAI. In 51/83 (60%) of the patients with residual disease activity according to the physician and a BASDAI >3.5 the treatment was left unchanged, either because of low disease activity as rated by the physician [n = 15 (29%)] or because of a combination of low disease activity with non-inflammatory complaints or comorbidities [n = 11 (25%)]. Retrospective treat-to-target evaluations showed that treatments were most frequently intensified in patients with arthritis or inflammatory back pain and less often in patients with other (non-inflammatory) musculoskeletal comorbidities. CONCLUSION: This study shows that physicians do not always strictly apply treat-to-target in case of residual disease activity in axSpA. Usually, they accept low disease activity as satisfactory.

[18F]Fluoride PET provides distinct information on disease activity in ankylosing spondylitis as compared to MRI and conventional radiography.

PURPOSE: To relate [18F]fluoride uptake on PET with abnormalities on magnetic resonance imaging (MRI) and conventional radiography (CR) in ankylosing spondylitis (AS) patients. METHODS: Ten clinically active AS patients (female 6/10, age 38 ± 11 years) were included, and both spine and SI-joints were examined. PET scans were dichotomously scored for enhanced [18F]fluoride uptake, MRI scans were scored for fatty lesions, erosions, ankylosis, and bone marrow edema (BME), and CR was scored for erosions, syndesmophytes, and ankylosis. The overlap of lesions across all modalities was evaluated through univariate and multivariate analyses using a generalized mixed model. RESULTS: In the spine, 69 lesions with enhanced [18F]fluoride uptake, 257 MRI lesions, and 88 CR lesions were observed. PET lesions were mostly located in costovertebral and facet joints, outside the field of view (FOV) of the MRI and CR. However, PET lesions inside the FOV of MRI and CR partially showed no abnormality on MRI and CR. In lesions with abnormalities on multiple modalities, both univariate and multivariate analysis showed that PET activity had the strongest association with BME on MRI and ankylosis on CR. In the SI joints, 15 lesions (75%) with PET uptake were found, with 87% showing abnormalities on MRI and CR. CONCLUSION: [18F]fluoride PET lesions are often found outside the scope of MRI and CR, and even in the same location show only partial overlap with abnormalities on MRI (especially BME) and CR (especially ankylosis). This suggests that [18F]fluoride PET partially visualizes aspects of AS separate from MRI and CR, providing novel information. CLINICAL TRIAL REGISTRATION: NL43223.029.13 registered at 02-05-2013.  https://www.toetsingonline.nl/to/ccmo_search.nsf/fABRpop?readform&unids=C1257BA2002CC066C1257B4E0049A65A.

Bone formation in ankylosing spondylitis during anti-tumour necrosis factor therapy imaged by 18F-fluoride positron emission tomography.

Objectives: Excessive bone formation is an important hallmark of AS. Recently it has been demonstrated that axial bony lesions in AS patients can be visualized using 18F-fluoride PET-CT. The aim of this study was to assess whether 18F-fluoride uptake in clinically active AS patients is related to focal bone formation in spine biopsies and is sensitive to change during anti-TNF treatment. Methods: Twelve anti-TNF-naïve AS patients [female 7/12; age 39 years (SD 11); BASDAI 5.5 ± 1.1] were included. 18 F-fluoride PET-CT scans were performed at baseline and in two patients, biopsies were obtained from PET-positive and PET-negative spine lesions. The remaining 10 patients underwent a second 18F-fluoride PET-CT scan after 12 weeks of anti-TNF treatment. PET scans were scored visually by two blinded expert readers. In addition, 18F-fluoride uptake was quantified using the standardized uptake value corrected for individual integrated whole blood activity concentration (SUVAUC). Clinical response to anti-TNF was defined according to a ⩾ 20% improvement in Assessment of SpondyloArthritis international Society criteria at 24 weeks. Results: At baseline, all patients showed at least one axial PET-positive lesion. Histological analysis of PET-positive lesions in the spine confirmed local osteoid formation. PET-positive lesions were found in the costovertebral joints (43%), facet joints (23%), bridging syndesmophytes (20%) and non-bridging vertebral lesions (14%) and in SI joints (75%). After 12 weeks of anti-TNF treatment, 18F-fluoride uptake in clinical responders decreased significantly in the costovertebral (mean SUVAUC -1.0; P < 0.001) and SI joints (mean SUVAUC -1.2; P = 0.03) in contrast to non-responders. Conclusions: 18F-fluoride PET-CT identified bone formation, confirmed by histology, in the spine and SI joints of AS patients and demonstrated alterations in bone formation during anti-TNF treatment.

Muscle wasting in male TNF-α blocker naïve ankylosing spondylitis patients: a comparison of gender differences in body composition.

Objective: To assess gender differences in body composition (BC) in a cohort of AS patients naïve to TNF-α blockers. Methods: Patients included fulfilled the Modified New York criteria for AS. Demographic information and disease activity measures (ASDAS and BASDAI) were reported. BC was measured by whole body DXA. Body fat percentage (BF%), fat mass index (FMI), fat free mass index (FFMI) and android/gynoid fat ratio were reported and compared between men and women and with the reference population (percentiles). Results: Seventy consecutive patients were included; 60% were men. Demographic variables were similar, except for dyslipidaemia (57.1% of men; 14.3% of women). Women had significantly more fat (BF%, FMI), and less muscle (FFMI) than men, but below the median of the reference population. Male AS patients had a markedly low FFMI (31.7th percentile) compared with the reference population. In the whole group, after multivariate analysis, an ASDAS CRP >3.5 was related to lower fat free mass content. In men, a significant relationship between having a high disease activity (ASDAS, BASDAI) and lower BF% or FMI percentile was found, but in women it was the opposite. Conclusion: Muscle wasting, measured as low FFMI compared with the reference population, was found in male TNF-α blocker naïve AS patients, especially in those with active disease. Women had higher volumes of body fat than men, but near the median of the reference population. The relationships between fat content and disease activity support the complex association between adipose tissue and inflammation.

Reproducibility of performance measures of physical function based on the BASFI, in ankylosing spondylitis.

OBJECTIVE: To establish the test-retest reproducibility of performance measures of physical function based on the Bath Ankylosing Spondylitis Functional Index (BASFI) questionnaire in patients with AS. METHODS: Data were obtained from 65 AS patients. They were tested on two occasions by one assessor with a 1-week interval. Physical function was assessed via eight performance measures based on items used in the BASFI questionnaire, representing activities of daily life, which AS patients frequently report to be problematic. For each activity, a performance score was determined. Pain and exertion were measured using a 10-cm horizontal visual analogue scale (VAS) and Borg's modified scale, respectively. Test-retest reproducibility was assessed for all measurements using intraclass correlation coefficients (ICCs) and by calculating the standard error of measurement (SEM). RESULTS: Adequate intrarater reliability was found. For performance scores, ICCs ranged from 0.73 to 0.96. Measurements of exertion and pain also showed adequate intrarater reliability, with the exception of one performance measure, namely the test for the ability to look over one's shoulder. For this test, the ICCs were 0.66 and 0.69 for exertion and pain, respectively. The remaining ICCs for exertion ranged from 0.71 to 0.88 and for pain from 0.74 to 0.83. The SEM for performance scores ranged from 4 to 9% of the observed score. The SEM for exertion ranged from 8 to 11% and for pain from 10 to 15%. CONCLUSIONS: Performance measures of physical function based on the BASFI questionnaire have adequate to excellent test-retest reproducibility. Due to the presence of measurement error, measurements are accurate for group assessment; repeated measurements are advised for an adequate assessment of individual patients.