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Medscape
a day ago
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- Medscape
First Scan for Suspected AxSpA: X-rays, MRI, or CT?
BARCELONA, Spain — Data from a prospective imaging study question the use of x-ray radiography first in the diagnostic workup of patients with suspected axial spondyloarthritis (axSpA), a practice that is currently a part of recommendations by the European Alliance of Associations for Rheumatology (EULAR). The study, which evaluated three different imaging pathways based on whether x-ray radiography, MRI, or CT of the sacroiliac joint (SIJ) was used first, found that the two latter approaches yielded a higher diagnostic efficacy than the radiograph-first approach. While just 13% of 30 people who were in the radiograph-first arm of the study were confirmed as having axSpA after the initial scan, 22% of 91 patients in the MRI-first and 30% of 84 people in the CT-first arms were given an axSpA diagnosis. X-ray, MRI, or CT first? Dominik Deppe, MD 'To x-ray or not to x-ray? What may sound somewhat philosophical, is a relevant question,' said study investigator Dominik Deppe, MD, who presented the findings at European Alliance of Associations for Rheumatology (EULAR) 2025 Annual Meeting. Deppe, a doctoral student in the Department of Radiology at Charité – Universitätsmedizin Berlin, Berlin, Germany, explained that although radiographs could show certain structural lesions, such as erosions, sclerosis, or ankylosis, and used relatively low levels of radiation, interpretation could be problematic. 'Even among experts, inter-reader reliability remains low,' Deppe said. MRIs are often performed if the results on radiography are negative or inconclusive. Such scans provide additional insights, he added, and can show both structural and inflammatory lesions, such as bone marrow edema. However, the high cost and low availability of MRI relative to radiography, however, were issues, he acknowledged. This is where CT could perhaps prove most useful. Although it's not part of the standard imaging pathway as yet, it is 'a gold standard for structural lesions,' Deppe said. He added: 'Historically, CT is considered to have high radiation exposure, but nowadays, we can perform CT with ultra-low dose techniques that allow us to reduce radiation exposure to a level that is comparable, or even less, compared to conventional x-rays.' Strategies Compared and Results The study included 205 people with suspected axSpA, who were randomly allocated into one of three arms: 30 to a radiograph-first or 'standard' arm, 91 to an MRI-first arm, and 84 to a CT-first arm. Scans were designated positive or negative by the consensus of two specialized musculoskeletal radiologists who were blinded to the clinical data. A positive result was defined as clear signs of structural or inflammation suggestive of axSpA and no further imaging was done. Those with negative scans underwent a subsequent scan with another method; those in the radiograph-first arm had an MRI scan and then a CT scan, those in the MRI-first arm had a CT scan, and those in the CT-first arm had an MRI scan. The results are preliminary because the study is ongoing and results from the final diagnosis by a rheumatologist are not yet available, Deppe said. He reported that in the radiograph-first arm, 26 (87%) people had a negative scan and then had an MRI scan. This was positive in three (11%) and negative in 23 (88%) of people. None of the people with a negative MRI scan had a positive CT scan. In the MRI-first arm, scans were positive in 20 (22%) and negative in 71 (78%) of people. Again, CT added no further cases among the people who were also MRI-negative. Finally, in the CT-first arm, there were 25 (30%) positive and 59 (70%) negative scans. MRI performed in the CT-negative patients detected two (3%) additional cases of confirmed axSpA. Deppe said: 'Our standard approach, [which] we're using right now, has the lowest diagnostic efficacy, compared to the MRI-first and CT-first approach.' Patient Characteristics Information about patient demographics were not presented, however, which prompted Uta Kiltz, MD, a senior rheumatologist at Rheumazentrum Ruhrgebiet, Herne, Germany, to ask for clarification and about the study design. 'Can you give some information about the population you included in the study?' she asked. 'I think we need to have some more context about the decision-making process to really understand the results.' Deppe responded that the patients had been referred with the suspicion and not confirmed diagnosis of axSpA and had been randomized through a third party into the three different imaging arms. Topline patient demographics had been given in the abstract, which stated that the mean age of the population studied was 38 years (SD, 10.58 years) and just over half (58%) were women. Around half (53%) of the study population was HLA-B27 positive. The mean C-reactive protein level was 3.66 mg/L, and the mean BMI was 25.57. The mean duration of back pain was around 8 years, and 70.6% of people had signs of inflammatory back pain. Questions Raised Several discussants raised concerns about the study design and the interpretation of these early findings. Eric Ruderman, MD, of Northwestern University Feinberg School of Medicine, Chicago, questioned why all patients did not receive all three imaging modalities: 'Ultimately, you don't know the diagnostic specificity of the [ultra] low-dose CT. Why didn't you do all three images in each patient, so that you can actually make a comparison once you have the confirmed diagnosis?' Deppe replied that the team wanted to be pragmatic: 'We wanted to evaluate the clinical settings where the patient does not undergo every imaging, but if we found positive results, as in the clinical practice, we don't need further imaging, and this is something we want to demonstrate in the study.' Xenofon Baraliakos, MD, head of rheumatology at the Rheumazentrum Ruhrgebiet, and the new president of EULAR, raised concerns about potential false positives: 'What happens if the x-ray is it was falsely positive? Have you been able to check for that?' Deppe acknowledged the limitation: 'I think this is something we have to do when we have the final diagnosis by the rheumatologist, to see whether we missed or misinterpreted some of the images.' This study was independently supported. Deppe had no conflicts of interest. The commentators were not involved in the study.
Medscape
09-06-2025
- Health
- Medscape
Sacroiliac MRI Lesions Set Apart axSpA and Other Back Pain
The analysis of structural lesions in sacroiliac joints using MRI showed distinct patterns of structural changes across multiple groups, with patients with axial spondyloarthritis (axSpA) showing higher rates of erosions and fatty lesions than other groups without axSpA. Inflammatory and structural lesions occurred simultaneously in those with axSpA. METHODOLOGY: Researchers assessed differences in the structural lesions appearing on sacroiliac joint MRIs in 172 participants (mean age, 30.1-34.3 years) from two projects comparing patients with axSpA with those without. They included patients with axSpA (n = 47) and those without axSpA comprising patients with chronic back pain (n = 47), women with postpartum back pain (n = 7), runners (n = 24), and healthy individuals (n = 47). Two trained, calibrated readers independently inspected the sacroiliac joint MRIs for erosions, fatty lesions, sclerosis, and ankylosis. A scoring system similar to that of the Spondyloarthritis Research Consortium of Canada scoring method was used for the assessment. Several structural lesion cutoffs were identified and tested as suggested by two working groups, with specific definitions for three or more erosions, three or more fatty lesions, and five or more erosions and/or fatty lesions. The frequency of patients meeting the cutoffs was assessed within different subgroups. TAKEAWAY: Structural lesions were identified in 79% of patients with axSpA and 13% of those without axSpA, with erosions (75% vs 9%) and fatty lesions (40% vs 4%) showing the most marked differences and sclerosis (13% vs 3%) and ankylosis (15% vs 2%) showing smaller group differences. Erosions were also prevalent in women with postpartum back pain (57%), and fatty lesions were the most prevalent in healthy individuals (6%). Significant differences were noted across groups for fatty lesions ( P < .001), erosions ( P < .001), and ankylosis ( P = .016); however, sclerosis showed no significant variation. The proposed cutoff definitions performed well in differentiating axSpA from non-axSpA. < .001), erosions ( < .001), and ankylosis ( = .016); however, sclerosis showed no significant variation. The proposed cutoff definitions performed well in differentiating axSpA from non-axSpA. In the axSpA group, an overlap of 72%-79% was observed between structural lesions and inflammation, while non-axSpA subgroups showed a significantly lower rate of overlap. However, 4%-29% of patients in the non-SpA subgroup compared with only 6% in the axSpA group had structural lesions without inflammation. IN PRACTICE: "We are convinced that if structural lesions ought to be part of axSpA classification criteria, the implementation of cut-offs for these lesions should be considered. Nevertheless, for a comprehensive understanding of the possible added value of structural lesions, it is crucial to look at the prevalence of structural lesions in the absence of inflammation," the authors wrote. SOURCE: This study was led by Zohra Kerami, Amsterdam UMC Locatie AMC, Amsterdam, the Netherlands. It was published online on May 28, 2025, in RMD Open . LIMITATIONS: The sample sizes were notably small for some subgroups. Additionally, comprehensive clinical and demographic information was lacking for healthy individuals, women with postpartum back pain, and runners. Data on previous pregnancies and the interval between MRI and delivery were not collected systematically, which limited the analysis of pregnancy-related effects. DISCLOSURES: This study did not receive any specific funding. Few authors reported receiving consultancy fees, research support, and/or speaking fees and honoraria for lectures or participation in advisory boards from various pharmaceutical companies. One author reported being an associate editor and another reported being an owner of Joint Imaging BV.
Medscape
30-05-2025
- Business
- Medscape
Misdiagnosing and Overdiagnosing AxSpA: An ‘Imaging Crisis?'
TORONTO — MRI is central to the early detection and diagnosis of axial spondyloarthritis (axSpA), but years-long diagnostic delays are still common. However, experts are warning that misinterpretation of MRI findings is contributing to significant increases in false-positive diagnoses in patients presenting with back pain that may be caused by other, noninflammatory conditions. The good news is that studies show that diagnostic accuracy in the interpretation of MRI findings can be significantly improved when rheumatologists provide radiologists with all the clinical information relevant to a diagnosis of axSpA. 'There is a high risk of misdiagnosis and overdiagnosis of axSpA in clinical practice,' said Denis Poddubnyy, MD, PhD, professor in the Division of Rheumatology, Temerty Faculty of Medicine at the University of Toronto, Toronto, Ontario, Canada. Denis Poddubnyy, MD, PhD 'In 2025, evidence of SpA-compatible active inflammatory and structural changes on MRI of the sacroiliac joints is needed for a diagnosis of axSpA,' he said in a presentation at the Spondyloarthritis Research and Treatment Network (SPARTAN) 2025 Annual Meeting. 'There's been a paradigm shift.' Evidence for this paradigm shift comes from the ongoing Improve-axSpA project, Poddubnyy said. The telemedicine initiative, which involves rheumatologists and orthopedists at 40 centers across Germany and Austria, is focused on enhancing the diagnosis of axSpA. Interim findings showed that clinicians misinterpreted the MRI findings in 35% of 476 cases of suspected axSpA submitted for central evaluation. These cases could be explained by noninflammatory conditions that mimic the symptoms of axSpA, said the investigators, led by Poddubnyy. These axSpA-like conditions include degenerative or mechanical changes in the sacroiliac joint (SIJ), degenerative disk disease, and osteitis condensans ilii — a mechanical condition that is often associated with bone marrow edema in the SIJs. 'I believe this [35%] figure is very accurate, not only for Europe — or Germany and Austria — but for anywhere that physicians are trying to apply MRI findings to make an early diagnosis,' Poddubnyy told Medscape Medical News . This finding could also account for a significant proportion of the 40%-50% of patients with axSpA who don't respond to treatment, he said. In the study, central evaluation ruled out axSpA in a whopping 75% of the 183 cases with an inconclusive local diagnosis. In the other 25% of these cases, the diagnosis could not be confirmed by central assessment because of insufficient imaging. This disturbing trend provides evidence of an 'imaging crisis' in axSpA, said Torsten Diekhoff, MD, PhD, a radiologist and associate professor, Charité — Universitätsmedizin Berlin, Berlin, Germany, in an editorial published on May 16, 2025, in The Lancet Rheumatology . Poddubnyy was a co-author. 'The prevailing dilemma in imaging of axial spondyloarthritis lies in the incongruence between early detection and the confidence of the imaging assessment,' they wrote. 'Although clinical work-around strategies have been developed to address this issue, they frequently fail to resolve the fundamental concern of achieving an early diagnosis before the manifestation of structural lesions.' When asked to comment, Jonathan Chan, MD, clinical associate professor, University of British Columbia, Vancouver, British Columbia, Canada, said there are 'definitely some major changes that we all agree are important.' One of them is acknowledging that MRI is a better tool than x-ray and that there is heavier weighting for MRI than for x-ray. 'We know that structural lesions are important, and we know that sometimes bone marrow edema can be intermittent, whereas the presence of multiple erosions will not reverse. That is something you can hang your hat on.' The consequences of diagnostic delay in patients with axSpA are well known and include less favorable treatment response and worse clinical outcomes. In 2019, an analysis of health insurance data in Germany from 1677 patients with axSpA revealed that diagnostic delay was common, with a mean of 5.7 years. The factors associated with longer time to diagnosis included female gender, negative HLA-B27 status, the presence of psoriasis, and a younger age at symptom onset. In its 2022 update of management recommendations for axSpA, members of the Assessment of Spondyloarthritis International Society (ASAS)-European Alliance of Associations for Rheumatology (EULAR) task force addressed the importance of ruling out alternative explanations for symptoms to avoid unnecessary treatment changes. The diagnostic accuracy of MRI imaging interpreted by physicians in clinical practice could be improved with expert support from a telemedicine platform that 'transcends borders,' said Poddubnyy, who is also a clinician investigator at the Schroeder Arthritis Institute, University Health Network, Toronto, Ontario, Canada. 'We want to diagnose patients early, but we need to be extremely careful about how we interpret the imaging of the sacroiliac joints and the spine,' he emphasized. What to Do When MRI Availability Is Limited For many clinicians, however, x-rays are the diagnostic imaging go-to, particularly in areas where access to MRI is limited. 'The specificity of x-rays is not great,' Poddubnyy said. 'If you have to perform x-rays first in your clinical setting, that's okay, but be extremely critical in terms of interpreting this imaging. If you have any doubts about whether axial disease is present, order a cross-sectional image.' When MRI is not readily available, CT may be a good alternative, he suggested. In the Improve-axSpA study, for instance, CT had higher specificity and produced fewer false-positive results than MRI. CT also captured more specific lesions, including erosions and ankylosis. Sharing clinical information can vastly improve MRI interpretation, a 2024 study showed. The results demonstrated that when rheumatologists gave radiologists essential clinical information relevant to the diagnosis of axSpA — not just patient age and gender — the precision and specificity of imaging interpretation significantly improved. When clinical information was available along with conventional radiographs, the precision of SIJ radiograph interpretation — meaning the percentage agreement between diagnosis by a rheumatologist and the radiology report confirming or excluding a diagnosis of axSpA — jumped from 70% to 78%. This kind of information-sharing doesn't happen routinely in clinical practice, said the investigators, led by Tim Pohlner, Charité — Universitätsmedizin Berlin. Some clinicians think that sharing essential clinical information will cause bias on the part of the radiologist, explained Poddubnyy. The expertise of both rheumatologists and radiologists is needed to diagnose axSpA, he added, and that means all information on clinical and imaging outcomes must be accessible. 'This is something that should be done in daily clinical practice, in every radiology setting,' Poddubnyy emphasized. 'Rheumatologists should be initiating this, bringing the radiologist to this idea.' The 2024 ASAS recommendations on clinical information to include on imaging referrals provide support for differentiating inflammatory from noninflammatory changes in patients with suspected or known axSpA. A downloadable checklist that can be shared with the radiologist includes information such as patient history, back pain characteristics, HLA-B27 status, physical activity level, pregnancy history, and SpA parameters. For Chan, who is also a clinical investigator at Arthritis Research Canada, Vancouver, British Columbia, Canada, the importance of sharing clinical information became evident while he was working on the CLASSIC study to revise classification criteria for axSpA in adults. 'We would meet every five scans and do a calibration with two or three central reader radiologists and then our local reader radiologist, who was using the 2009 [ASAS] classification criteria. After…our local reader realized what he was missing and what he needed to look for, it was very easy for him to' change the way he practiced. When asked to comment, Walter P. Maksymowych, MBChB, professor of medicine at the University of Alberta, Edmonton, Alberta, Canada, agreed that sharing clinical information such as HLA-B27 status is important. However, he emphasized that classification criteria for axSpA should not be used to diagnose the disease in clinical practice. Walter P. Maksymowych, MBCh 'These criteria are aimed at identifying patients with shared clinical characteristics for the purposes of clinical research, especially clinical trials research,' he said. 'I do think they help highlight key lessons,' he added, 'particularly the importance of MRI as a diagnostic tool.' Education to Improve Diagnostic Accuracy Education of both rheumatologists and radiologists is needed to improve diagnostic accuracy in axSpA, Poddubnyy said in a recent commentary in Nature Reviews Rheumatology . 'Rheumatologists need appropriate training to recognize the potential imaging pitfalls when diagnosing axSpA,' wrote Poddubnyy and Xenofon Baraliakos, MD, PhD, head of Rheumatology at the Rheumazentrum Ruhrgebiet, in Herne, Germany. Baraliakos is also president-elect of EULAR and past president of ASAS. 'Radiologists require specialized knowledge in interpreting MRI (as well as other imaging) findings in the sacroiliac joints and spine and guidance on how to differentiate inflammatory from mechanical or degenerative changes,' they wrote. Looking ahead, Poddubnyy and Baraliakos noted the emergence of artificial intelligence (AI) and AI-assisted tools in the imaging arena. Early evidence shows that AI can detect subtle patterns of inflammation and structural damage and could potentially increase the accuracy of interpreting axSpA-specific changes. Molecular imaging of inflammatory molecules using modalities such as PET could also prove valuable for determining whether bone marrow edema is related to axSpA or to mechanical stress or degenerative changes. In the meantime, the ASAS interactive online case library is an important resource for both rheumatologists and radiologists, Poddubnyy and Baraliakos said. It provides clinical cases with imaging that represent the entire spectrum of axSpA and the most common differential diagnoses. Other resources include the 2024 international ASAS-SPARTAN standardized image acquisition protocol for diagnostic evaluation of the SIJs by MRI and the 2024 international ASAS recommendations for reporting SIJ imaging, which detail ways in which alternative diagnoses can be considered. Online tools, training, and continuing medical education programs are also available at CARE Arthritis Ltd., said Maksymowych, who is chief medical officer. 'We have instructions on how MRI imaging should be performed and how it should be interpreted, with an extensive library of MRI scans in a DICOM [Digital Imaging and Communications in Medicine] format. We also provide other tools for clinicians, such as how to assess enthesitis, do a physical exam, and so on.' When all is said and done, early diagnosis increases the likelihood of a good treatment response. 'The earlier, the better,' Poddubnyy said. Studies of patients with symptoms of 3-5 years' duration have demonstrated the highest response rates, including remission, he pointed out. 'I'm pretty much convinced that early diagnosis and early treatment, and achieving an early inflammation-free and symptom-free state, will decrease the likelihood of chronic pain and the development of fibromyalgia,' Poddubnyy said. 'And with early and appropriate control of inflammation, we should be able to prevent the progression of structural damage, especially in the spine, and avoid long-term disability caused by ankylosis.'
Medscape
14-05-2025
- Health
- Medscape
Revised AxSpA Classification Criteria Ready for Prime Time
TORONTO — After almost 10 years, the much-anticipated revision of the current classification criteria for the diagnosis of axial spondyloarthritis (axSpA) is ready for prime time. An abstract of the modified criteria is being submitted for presentation at American College of Rheumatology 2025 Annual Meeting in October, said Walter P. Maksymowych, MBChB, professor of rheumatology at the University of Alberta, Edmonton, Alberta, Canada. Walter P. Maksymowych, MBChB The revised criteria 'have a specificity of almost 90% and will ensure homogeneous trial populations,' he said during a presentation at Spondyloarthritis Research and Treatment Network (SPARTAN) 2025 Annual Meeting. The modifications were developed using a worldwide dataset from the Classification of Axial Spondyloarthritis Inception Cohort (CLASSIC) trial. Maksymowych is the principal investigator. The criteria are not meant to be used for the diagnosis of axSpA in clinical practice, he told Medscape Medical News . Admittedly, the revisions will provide greater diagnostic certainty for clinicians wanting to enroll patients in trials. However, the criteria were modified to help investigators identify classic cases of axSpA suitable for clinical trials. Help Is On the Way to 'Identify an MRI That's Indicative of AxSpA' 'These criteria may limit generalizability, but regulatory bodies such as the FDA [US Food and Drug Administration] and the EMA [European Medicines Agency] will see this as of benefit due to reduced misclassification,' Maksymowych said. 'We want to help radiologists in particular, but also rheumatologists, identify an MRI that's indicative of axSpA. We also thought it was important to identify the clinical factors associated with a diagnosis of axSpA when the MRI imaging is negative.' Concerns about the current classification criteria, developed in 2009 by the Assessment of SpondyloArthritis International Society (ASAS), surfaced shortly after implementation. Although the criteria made it possible to distinguish axial from peripheral disease, and to diagnose axSpA earlier using an MRI, there were reports of inconsistencies and lower clinical trial response rates. The prospective CLASSIC trial was an ASAS-SPARTAN initiative launched to test the performance of the criteria using prespecified sensitivity and specificity targets of ≥ 75% and ≥ 90%, respectively. The trial recruited 1015 patients aged 45 years or younger from 61 centers in 27 countries. All had been consecutively referred to a rheumatologist for lower back pain of at least 3 months' duration and suspected spondyloarthritis. The findings showed that the sensitivity of the 2009 criteria varied from 73.8% to 82.4% and the specificity ranged from 77.1% to 84.3%, depending on the source of imaging data and the stage of global diagnostic evaluation. Revising the 2009 criteria is a very important follow-up project, Maksymowych said. In 2016, the work of modifying the criteria to a specificity threshold of 90% or more was taken on by the ASAS-SPARTAN criteria classification steering committee. The approach was data-driven, with some minor expert consensus modifications along the way. A multivariate analysis of data from the CLASSIC trial showed that inflammation in the sacroiliac joints (SIJs) on an MRI — even before visible evidence of the structural change — was the most important independent variable associated with the diagnosis of axSpA. The second most important independent variable was inflammatory back pain, followed by the presence of the HLA-B27 allele. Lianne Gensler, MD Revisions to the current criteria are long overdue, said Lianne Gensler, MD, professor of medicine at the University of California San Francisco (UCSF) and a member of the steering committee. Some of the issues surrounding the 2009 criteria were the result of clinicians using them as diagnostic criteria, she said in an interview. In clinical practice, the focus is on diagnostic sensitivity not specificity, explained Gensler, who is director of the UCSF Ankylosing Spondylitis Clinic. 'The goal is to capture all patients with axSpA, including the atypical cases, because you need to treat them. But with classification criteria, the goal is to identify typical cases that will allow researchers to draw an inference. The patient population is much more restricted.' The modified criteria have a table format, which brings them into alignment with classification criteria for all rheumatic diseases, Maksymowych said. There is also a scoring system with a cutoff of 11 points. 'Classification Criteria Scoring System Really Reflects Clinical Decision-Making' Liron Caplan, MD, PhD 'Mathematically, it's a simple concept, but the classification criteria scoring system really reflects clinical decision-making,' said Liron Caplan, MD, PhD, associate professor of rheumatology at the University of Colorado, Aurora, Colorado. 'The data from CLASSIC show that confidence takes a big leap when rheumatologists have the imaging data available, specifically the MRI,' he told Medscape Medical News . The clinical features selected for a diagnosis of axSpA all have an objective manifestation, such as uveitis — 'that painful, red, inflamed eye' — and inflammatory bowel disease, said Caplan, who leads the steering committee and is a past chair of SPARTAN. 'Interpretation of MRI Imaging of Certain Negative States Is Key' The revised criteria rely very much on the imaging, 'even though a lot of people like to think that, 'Yes, well, we can do this clinically,'' Caplan pointed out. 'Interpretation of the MRI imaging of certain negative states is key.' Rheumatologists should be talking to radiologists about how to get the MRI done, Maksymowych emphasized in his presentation. 'Bone marrow edema seen in two consecutive slices is no longer sufficient for a diagnosis of axSpA.' In the CLASSIC trial, MRI was performed at all SPARTAN and most ASAS sites using the first standardized MRI image acquisition protocol (IAP) to diagnose inflammation of the SIJs, he said. 'When you're looking at an MRI, you're not just looking at inflammatory lesions, you're looking at all the sequences simultaneously and ascertaining other structural and inflammatory lesions at the same time.' The IAP, to which 91% of delegates voted 'yes' at the 2022 annual meeting of ASAS, includes at least four sequences of the SIJs in two planes orthogonal to the sacrum. Inflammation-, fat-, and erosion-sensitive sequences are considered critical for the optimal visualization of inflammation, structural damage, and the bone-cartilage interface. The standardized IAP for SIJ MRI diagnosis can be applied to any MRI scanner and delivers 'superb' imaging — 'better than you'd see in any clinical trial today,' Maksymowych said. It should be performed within 6 weeks of the patient visit, he added, 'whilst the clinical data is still fresh in the mind of the rheumatologist.' So what's next? 'We've got this phenomenal dataset. Our imaging dataset is unique,' Maksymowych said. 'We need to provide clear guidance around interpretation of an MRI and transfer knowledge to rheumatologists and radiologists about what constitutes inflammatory back pain.'
