The 2023 ACR/EULAR classification criteria for calcium pyrophosphate deposition disease

Dual-Energy Computed Tomography Applications in Rheumatology

Dual-energy computed tomography (DECT) has emerged as a transformative tool in the past decade. Initially employed in gout within the field of rheumatology to distinguish and quantify monosodium urate crystals through its dual-material discrimination capability, DECT has since broadened its clinical applications. It now encompasses various rheumatic diseases, employing advanced techniques such as bone marrow edema assessment, iodine mapping, and collagen-specific imaging. This review article aims to examine the unique characteristics of DECT, discuss its strengths and limitations, illustrate its applications for accurately evaluating various rheumatic diseases in clinical practice, and propose future directions for DECT in rheumatology.

Imaging of crystal-induced arthropathies in 2025

In recent years, imaging has become an essential tool in the assessment of crystal-induced arthropathies (CIAs), including gout, calcium pyrophosphate deposition disease, and basic calcium phosphate crystal deposition. Advances in imaging have improved diagnosis and disease monitoring, leading to its integration into classification criteria and clinical guidelines. Ultrasound (US), conventional radiography (CR), and dual-energy computed tomography (DECT) each offer unique advantages. US is a widely accessible, cost-effective, and dynamic tool, while DECT provides crystal-specific images, aiding particularly in gout diagnosis. CR, though less sensitive to early crystal deposition, remains valuable for evaluating structural damage and chronic changes. Despite these advances, challenges remain. The specificity and sensitivity of imaging findings need further validation, and the clinical relevance of certain imaging features is debated. This review summarizes recent developments, highlights key strengths, and discusses unresolved issues, emphasizing areas where future research is needed to optimize imaging use in CIAs.

Core domain set for chronic and/or recurrent manifestations of calcium pyrophosphate deposition disease: OMERACT delphi survey to establish consensus

OBJECTIVE

To agree on important domains for the Outcome Measures in Rheumatology (OMERACT) core domain set for chronic and/or recurrent manifestations of calcium pyrophosphate deposition (CPPD) disease.

METHODS

Patient research partners (PRPs) and other participants (mainly clinicians and researchers) contributed to three rounds of a consensus survey using Delphi methodology. Consensus was defined if ≥70% of both patients and other participants scored the domain as 'critically important domain to include'. In a subsequent ranking exercise, all participants were asked to select and rank up to 10 of the domains reaching consensus.

RESULTS

Fifteen domains reached consensus as critically important. Within the Pathophysiological Manifestations area, these were joint pain, joint tenderness, joint swelling, acute CPP crystal arthritis flare, joint damage on imaging tests, joint calcification on imaging tests, and crystals in joint fluid. Within the Life Impact area, these were overall function, ability to complete daily tasks, ability to work, health related quality of life, patient global assessment response to treatment, patient global assessment of disease activity, physician global assessment of disease activity, and patient satisfaction with treatment. No domains within the Societal/Resource Use area reached consensus as critically important. In the ranking exercise, joint pain, joint tenderness, joint swelling, acute CPP crystal arthritis flare and overall function were most highly ranked.

CONCLUSION

This work has identified potential domains for the OMERACT core domain set for chronic and/or recurrent manifestations of CPPD disease. There was strong support for joint pain, joint tenderness, joint swelling, acute CPP crystal arthritis flare, overall function, and global assessments of disease activity as core domains.

Association Between Vascular Calcifications on Joint Radiographs and Calcium Pyrophosphate Crystal Arthritis: A Medical Records Review Study

OBJECTIVE

Previous studies have shown an association between chondrocalcinosis (CC) and vascular calcifications (VCs). This study aimed to investigate the association of VCs detected on joint radiographs (XRs) of older patients diagnosed with calcium pyrophosphate (CPP) arthritis compared with a control group with osteoarthritis (OA).

METHODS

A medical records review study of joint radiographs (knee and wrist) was conducted. CPP crystal arthritis was diagnosed based on at least 1 documented episode of arthritis with synovial fluid analysis positive for CPP crystals or imaging showing CC at 1 or more sites, with no alternative inflammatory arthritis diagnosis. The control group comprised patients with OA and no CC, matched 1:1 for age and sex. All participants were over 60 years of age. XRs were reviewed for CC, OA, and VCs at the affected joint by 2 independent observers.

RESULTS

A total of 98 patients were enrolled in both the CPP arthritis group and the OA group. VCs adjacent to the affected joint were detected in 69 patients of the CPP group and 19 patients of the control group (70.4% vs 19.4%, p < 0.001). Among patients aged 60 to 80 years, the presence of VCs on XRs was highly indicative of CPP, demonstrating a specificity of 89.2% (95% confidence interval: 79.1%-95.6%). In the CPP group, patients with VCs had a significantly higher prevalence of cardiovascular (CV) comorbidities.

CONCLUSIONS

The detection of VCs on XRs was strongly associated with CPP crystal arthritis. The presence of VCs may further serve as a biomarker for an increased burden of CV comorbidities.

Core domain set for studies of acute calcium pyrophosphate crystal arthritis: OMERACT delphi survey to establish consensus

OBJECTIVE

To identify potential domains for the Outcome Measures in Rheumatology (OMERACT) core domain set for studies of an individual flare of acute calcium pyrophosphate (CPP) crystal arthritis.

METHODS

Patient research partners (PRPs) and other participants (mainly clinicians and researchers) completed three rounds of survey using Delphi methodology. Consensus was defined as ≥ 70 % of both PRP and other participants groups rated the domain as a 'critically important domain to include'. In a subsequent ranking exercise, all participants were asked to rank and comment on up to 10 domains to include as core domains.

RESULTS

Fourteen domains reached consensus as critically important in the Delphi survey. In the Pathophysiological Manifestations area, the domains were joint pain, joint tenderness, joint swelling, joint inflammation on imaging tests and duration of acute CPP crystal arthritis flare. In the Life Impact area, the domains were overall function, ability to complete daily tasks, ability to work, health related quality of life, patient global assessment response to treatment, patient and physician global assessments of disease activity, and patient satisfaction with treatment. In the Societal/Resource Use area, use of rescue medications reached consensus. In the ranking exercise, joint pain, joint tenderness, joint swelling, overall function and ability to complete daily tasks ranked highest.

CONCLUSION

Joint pain, joint swelling, joint tenderness, duration of acute CPP crystal arthritis flare, overall function, ability to complete daily tasks, and patient global assessment of disease activity received the strongest support to be included in the OMERACT core domain set for studies of acute CPP crystal arthritis.

Cervical proprioception, postural control, and pain: unraveling the interconnected challenges in rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a chronic autoimmune disease that impairs proprioception and postural control, increasing fall risk and reducing quality of life. This study evaluated cervical proprioception and postural control in RA patients versus asymptomatic individuals, examined their relationship within the RA group, and investigated pain's mediating effects on this association.

METHODS

In this cross-sectional study, 82 RA patients and 82 age- and gender-matched controls were recruited. Cervical proprioception was assessed using the Cervical Joint Position Error Test (CJPET), while postural control was evaluated via a stabilometric force platform measuring center-of-pressure length (L CoP), 95% confidence ellipse sway area (ESA 95%), and center-of-pressure velocity (V CoP). Statistical analyses included t-tests, correlation, regression, and mediation analysis to evaluate relationships and the role of pain in cervical proprioception and postural control.

RESULTS

RA patients demonstrated significantly impaired cervical proprioception and postural control compared to controls (p < 0.001). Significant differences were observed in cervical flexion, extension, rotation, and postural control measures (L CoP, ESA 95%, and V CoP; p < 0.001 for all parameters). Pearson's correlations revealed significant relationships between cervical proprioception and postural control parameters. Regression analysis indicated that cervical proprioception, particularly when combined with age and disease duration, significantly predicted postural control. Mediation analysis revealed that pain significantly mediated the relationship between cervical proprioception and postural control.

CONCLUSIONS

Cervical proprioception is significantly reduced in RA patients and strongly influences postural control. Pain serves as a key mediator in this relationship, emphasizing the need for effective pain management to enhance proprioceptive and postural functions in RA patients. These findings suggest that the insights from this cross-sectional study could inform future interventions aimed at enhancing proprioception and managing pain, which may significantly benefit RA patients' postural stability and overall quality of life.

Advanced imaging techniques in crystal arthritis

Gout and calcium pyrophosphate deposition (CPPD) disease are the most common causes of crystal arthritis. Identifying the pathogenic crystal deposition is the cornerstone of the diagnosis, but also prognosis and monitoring of the diseases. Conventional radiography has been for decades the only imaging technique used, with its very restricted sensitivity in both diseases. Advanced techniques, namely ultrasound and dual-energy computed tomography (DECT), are being increasingly used in the diagnosis and management of gout and CPPD diseases, and their role is now well recognized in classification criteria and in recommendations for the diagnosis and management. In gout, ultrasound elementary lesions of monosodium urate deposition are well defined and have been shown to be sensitive to change and can be monitored, while direct quantification of these deposits can be performed with DECT. In CPPD disease, the definition of elementary lesions and their scoring has been well established for ultrasound, while the proof of concept that DECT can help discriminate calcium pyrophosphate crystal deposits among other calcium-containing structures has been shown. The aim of this narrative review is to provide an overview of the use of advanced imaging techniques in crystal-induced arthropathies.

Systematic literature review on Calcium Pyrophosphate Deposition (CPPD) nomenclature: condition elements and clinical states- A Gout, Hyperuricaemia and Crystal-Associated Disease Network (G-CAN) consensus project

OBJECTIVES

The Gout, Hyperuricaemia and Crystal-Associated Disease Network (G-CAN) has developed a calcium pyrophosphate deposition (CPPD) nomenclature project. This systematic literature review constituted its first step and aimed to provide a state-of-the-art analysis of the medical literature of the last 20 years.

METHODS

A systematic literature search was undertaken in the PubMed, Cochrane and Embase databases between 2000 and 2022, restricted to studies on humans and in the English language. Eight reviewers independently and manually extracted labels related to CPPD concepts, according to an a priori list generated by the authors: pathogenic conditions and pathogenic crystal labels, elementary imaging condition elements and asymptomatic and symptomatic condition states. For each concept, labels were analysed to determine their frequency.

RESULTS

Among the 2375 articles identified, 886 articles were included, of which 394 (44.5%) were case reports and 169 (19.0%) were scoping reviews. Overall, the most common labels used to designate the pathogenic condition were 'pseudogout' in 365/783 (46.6%), 'chondrocalcinosis' in 207/783 (26.4%) and 'calcium pyrophosphate deposition disease' in 181/783 (23.1%) occurrences. The most common abbreviation was 'CPPD' in 312/390 (80.0%), but with different meanings. CPPD clinical phenotypes were often described as 'pseudo-form' labels.

CONCLUSION

Those results demonstrate the heterogeneity of labels used to describe CPPD condition concepts, with wide variation in condition labels in the medical literature. This work provides the rationale and basis to achieve agreement about CPPD technical nomenclature.

Features Associated With Different Inflammatory Phenotypes of Calcium Pyrophosphate Deposition Disease: A Study Using Data From the International American College of Rheumatology/EULAR Calcium Pyrophosphate Deposition Classification Criteria Cohort

OBJECTIVE

The study objective was to examine the disease, demographic, and imaging features associated with different inflammatory phenotypes of calcium pyrophosphate deposition (CPPD) disease, ie, recurrent acute calcium pyrophosphate (CPP) crystal arthritis, chronic CPP crystal inflammatory arthritis, and crowned dens syndrome (CDS).

METHODS

Data from an international cohort (assembled from 25 sites in 7 countries for the development and validation of the 2023 CPPD classification criteria from the American College of Rheumatology/EULAR) that met the criteria were included. Three cross-sectional studies were conducted to determine the phenotypic characteristics of recurrent acute CPP crystal arthritis, chronic CPP crystal inflammatory arthritis, and CDS. Multivariable logistic regression analysis was used to calculate adjusted odds ratio (aOR) and 95% confidence interval (CI) to examine the association between potential risk factors and the inflammatory phenotype.

RESULTS

Among the 618 people included (56% female; mean age [standard deviation] 74.0 [11.9] years), 602 (97.4%) had experienced acute CPP crystal arthritis, 332 (53.7%) had recurrent acute arthritis, 158 (25.6%) had persistent inflammatory arthritis, and 45 (7.3%) had had CDS. Recurrent acute CPP crystal arthritis associated with longer disease duration (aOR 2.88 [95% CI 2.00-4.14]). Chronic CPP crystal inflammatory arthritis was associated with acute wrist arthritis (aOR 2.92 [95% CI 1.81-4.73]), metacarpophalangeal joint osteoarthritis (aOR 1.87 [95% CI 1.17-2.97]), and scapho-trapezo-trapezoid (STT) joint osteoarthritis (aOR 1.83 [95% CI 1.15-2.91]), and it was negatively associated with either metabolic or familial risk for CPPD (aOR 0.60 [95% CI 0.37-0.96]). CDS was associated with male sex (aOR 2.35 [95% CI 1.21-4.59]), STT joint osteoarthritis (aOR 2.71 [95% CI 1.22-6.05]), and more joints affected with chondrocalcinosis (aOR 1.46 [95% CI 1.15-1.85]).

CONCLUSION

CPPD disease encompasses acute and chronic inflammatory phenotypes, each with specific clinical and imaging features that need to be considered in the diagnostic workup.

Efficacy and safety of 10 mg versus 30 mg of oral prednisolone for acute CPP crystal arthritis: findings of a randomized controlled trial

INTRODUCTION

The optimal prednisolone dose for managing acute calcium pyrophosphate (CPP) crystal arthritis remains unclear. We compared the efficacy and safety of 10- and 30-mg daily doses of prednisolone for acute CPP crystal arthritis.

METHOD

This randomized, controlled, open-label trial included patients with acute CPP crystal arthritis and symptoms that had begun less than 72 h earlier. Patients without CPP crystals, those with septic arthritis, and those with uncontrolled infections were excluded. Participants received either 10 or 30 mg of prednisolone daily for 7 days. The primary outcome was time until complete resolution of symptoms; secondary outcomes included time until clinical resolution, recurrence rates, laboratory profiles, and adverse events, adjusted for confounders.

RESULTS

Seventy-nine patients participated. Baseline characteristics were comparable, except that the 30-mg recipients had more initial inpatient visits (p = 0.03). The median time until complete resolution was 7 days in both groups (p = 0.73). The 30-mg recipients exhibited faster clinical resolution (1 vs. 3 days; p = 0.03), but adjusted analyses revealed no significant differences in time until complete resolution (6.2 vs. 6.5 days; p = 0.68) or clinical resolution (2.4 vs. 2 days; p = 0.27). The overall recurrence rate was 14.3%; the 30-mg recipients experienced slightly more recurrences (p = 0.08). The other secondary outcomes did not differ significantly.

CONCLUSIONS

The 10- and 30-mg daily doses of prednisolone were equally effective in treating acute symptoms of CPP crystal arthritis, with no significant differences in resolution time, recurrence rates, or safety outcomes.

Calcium pyrophosphate deposition disease

Calcium pyrophosphate deposition (CPPD) disease is a consequence of the immune response to the pathological presence of calcium pyrophosphate (CPP) crystals inside joints, which causes acute or chronic inflammatory arthritis. CPPD is strongly associated with cartilage degradation and osteoarthritis, although the direction of causality is unclear. This clinical presentation is called CPPD with osteoarthritis. Although direct evidence is scarce, CPPD disease might be the most common cause of inflammatory arthritis in older people (aged >60 years). CPPD is caused by elevated extracellular-pyrophosphate concentrations in the cartilage and causes inflammation by activation of the NLRP3 inflammasome. Common risk factors for CPPD disease include ageing and previous joint injury. It is uncommonly associated with metabolic conditions (eg, hyperparathyroidism, haemochromatosis, hypomagnesaemia, and hypophosphatasia) and genetic variants (eg, in the ANKH and osteoprotegerin genes). Apart from the detection of CPP crystals in synovial fluid, imaging evidence of CPPD in joints by mainly conventional radiography, and increasingly ultrasonography, has a central role in the diagnosis of CPPD disease. CT is useful in showing calcification in axial joints such as in patients with crowned dens syndrome. To date, no treatment is effective in dissolving CPP crystals, which explains why control of inflammation is currently the main focus of therapeutic strategies. Prednisone might provide the best benefit-risk ratio for the treatment of acute CPP-crystal arthritis, but low-dose colchicine is also effective with a risk of mild diarrhoea. Limited evidence suggests that colchicine, low-dose weekly methotrexate, and hydroxychloroquine might be effective in the prophylaxis of recurrent flares and in the management of persistent CPP-crystal inflammatory arthritis. Additionally, biologics inhibiting IL-1 and IL-6 might have a role in the management of refractory disease.

Development of a deep learning model for automated detection of calcium pyrophosphate deposition in hand radiographs

Background

Calcium pyrophosphate deposition (CPPD) disease is a leading cause of arthritis, which can mimic or strongly interfere with other rheumatic diseases such as gout, osteoarthritis (OA) or rheumatoid arthritis (RA). In the recently established ACR/EULAR CPPD classification criteria, calcification and OA features of the wrist and hand joints are substantial features.

Objectives

To develop and test a deep-learning algorithm for automatically and reliably detecting CPPD features in hand radiographs, focusing on calcification of the triangular fibrocartilage complex (TFCC) and metacarpophalangeal (MCP)-2 and -3 joints, in separate or combined models.

Methods

Two radiologists independently labeled a dataset of 926 hand radiographs, yielding 319 CPPD positive and 607 CPPD negative cases across the three sites of interest after adjudicating discrepant cases. CPPD presence was then predicted using a convolutional neural network. We tested seven CPPD models, each with a different combination of sites out of TFCC, MCP-2 and MCP-3. The model performance was assessed using the area under the receiver operating characteristic (AUROC) and area under the precision-recall (AUPR) curves, with heatmaps (Grad-CAM) aiding in case discrimination.

Results

All models trialed gave good class separation, with the combined TFCC, MCP-2 and MCP-3 model showing the most robust performance with a mean AUROC of 0.86, mean AUPR of 0.77, sensitivity of 0.77, specificity of 0.80, and precision of 0.67. The TFCC-alone model had a slightly lower mean AUROC of 0.85 with a mean AUPR of 0.73. The MCP-2-alone and MCP-3-alone models exhibited mean AUROCs of 0.78-0.87, but lower mean AUPRs of 0.29-0.47. Heatmap analysis revealed activation in the regions of interest for positive cases (true and false positives), but unexpected highlights were encountered possibly due to correlated features in different hand regions.

Conclusion

A combined deep-learning model detecting CPPD at the TFCC and MCP-2/3 joints in hand radiographs provides the highest diagnostic performance. The algorithm could be used to screen larger OA or RA databases or electronic medical records for CPPD cases. Future work includes dataset expansion and validation with external datasets.

Computed tomography-current status and future directions for arthritis imaging

Applications of computed tomography (CT) in arthritis imaging have rapidly expanded in recent years due to ongoing technical developments. Dual-energy CT (DECT) has become indispensable in clinical practice, particularly for diagnosing gouty arthritis and assessing bony structural changes. Technological innovations such as low-dose CT and state-of-the-art reconstruction algorithms reduce radiation exposure while maintaining image quality and short acquisition times. This review explores the growing role of CT in arthritis imaging. Recent innovations have extended DECT's utility beyond gout diagnosis to the detection of inflammatory changes in various arthritic conditions. Postprocessing techniques such as the generation of subtraction images and iodine maps provide valuable insights into tissue perfusion and inflammatory activity, crucial for arthritis management. DECT can distinguish calcium from uric acid crystals, facilitating the differential diagnosis of various crystal arthropathies in a variety of clinical settings. This ability is particularly valuable in distinguishing between different clinical conditions in patients with inflammatory joint changes within a single imaging examination. Moreover, the advent of four-dimensional CT promises a better assessment of dynamic joint instabilities and ligament injuries, especially in the wrist. Overall, DECT offers a comprehensive approach to arthritis imaging, from the detection of structural changes to the assessment of active inflammation in joints and tendons. Continuous advances in CT technology, including photon-counting CT, hold promise for further improving diagnostic accuracy and expanding the role of CT in arthritis imaging and therapy monitoring.

Calcium Pyrophosphate Crystal Formation and Deposition: Where Do we Stand and What Does the Future hold?

PURPOSE OF THE REVIEW

Although calcium pyrophosphate deposition (CPPD) has been known since the 1960s, our understanding of its pathogenesis remains rudimentary. This review aims to illustrate the known mechanisms underlying calcium pyrophosphate (CPP) crystal formation and deposition and explore future directions in research. By examining various perspectives, from basic research to clinical and imaging assessments, as well as new emerging methodologies, we can establish a starting point for a deeper understanding of CPPD pathogenesis.

RECENT FINDINGS

Recent years have seen significant advances in CPPD research, particularly in the clinical field with the development of the 2023 ACR/EULAR classification criteria for CPPD disease, and in imaging with the introduction of the OMERACT ultrasonographic definitions and scoring system. However, progress in basic research has been slower. New laboratory approaches, such as Raman spectroscopy and omics sciences, offer promising insights that may help piece together the puzzle of CPPD. CPPD is a common yet understudied condition. As the population ages and CPPD becomes more prevalent, there is an urgent need to better understand the disease and the mechanisms involved in crystal formation and deposition, in order to improve diagnosis and therapeutic approaches.

Dual-Energy Computed Tomography Applications in Rheumatology

Dual-energy computed tomography (DECT) has emerged as a transformative tool in the past decade. Initially employed in gout within the field of rheumatology to distinguish and quantify monosodium urate crystals through its dual-material discrimination capability, DECT has since broadened its clinical applications. It now encompasses various rheumatic diseases, employing advanced techniques such as bone marrow edema assessment, iodine mapping, and collagen-specific imaging. This review article aims to examine the unique characteristics of DECT, discuss its strengths and limitations, illustrate its applications for accurately evaluating various rheumatic diseases in clinical practice, and propose future directions for DECT in rheumatology.

Acute Neck Pain from Crowned Dens Syndrome: A Case Report and Clinical Insights

BACKGROUND Crowned dens syndrome (CDS) is a rare condition characterized by deposition of calcium pyrophosphate crystals on the odontoid process of the second cervical vertebra, forming a calcified 'crown', with neck pain being a common symptom. The disorder exhibits unique clinical and radiological features, resembling manifestations of meningitis, such as acute headaches and cervical stiffness. There are few case reports and case series related to CDS. Patients generally respond well to treatment with nonsteroidal anti-inflammatory drugs (NSAIDs), although there is a certain rate of recurrence. Since there are few reports of CDS, we sought to publish this case report, aiming of increasing clinicians' awareness and reducing misdiagnosis rates. CASE REPORT A 62-year-old man presented to the Emergency Department with "cutting-like" headaches and neck pain for 2 days, and was subsequently diagnosed with CDS by cervical computed tomography (CT) scan, and hematological tests revealed inflammatory manifestations. He was advised to take oral nonsteroidal anti-inflammatory drugs and to rest; his symptoms improved after 3 days and his neck pain had almost resolved after 2 months. CONCLUSIONS In older patients experiencing new headaches and neck pain, along with increased inflammatory markers, particularly those with a history of pseudogout, the possibility of CDS should be considered. Case reports suggest that oral NSAIDs and short courses of corticosteroids can generally alleviate symptoms. Further research is needed on CDS diagnosis and treatment.

Acute coronary syndrome in calcium pyrophosphate deposition disease patients: A US inpatient care cohort study

OBJECTIVE

Recent studies have shown that CPPD might be associated with a higher risk of cardiovascular events related to inflammation. Thus, we aim to examine the outcomes of patients admitted for acute coronary syndrome (ACS) with and without CPPD.

METHODS

We used data from the US National Inpatient Sample (NIS) Database to identify patients who were admitted for ACS between 2006 and 2019. The ICD-9 and -10 codes were used to determine the patients with ACS related hospitalizations and of those, we classified two groups of patients: those with and those without any CPPD code. Data collection included demographics and comorbidities. Outcomes were in-hospital mortality, length of stay, hospital charges, and in-hospital complications. Associations between CPPD and specific morbidity were evaluated with chi-square tests. T-tests were used for continuous variables. We have also presented odds ratio (OR) along with 95 % confidence intervals (CI) for the outcomes of interest.

RESULTS

A total of 17,322,362 patients were admitted for ACS. Among them, 7,458 had CPPD, with a mean age of 75 years and 48 % were females. CPPD patients were more likely to be older (75 vs 68 years; p < 0.001) compared to non-CPPD patients. Among the comorbidities, chronic kidney disease was more frequently observed in CPPD patients. Regarding the inpatient complications, acute ischemic stroke and post-procedural hemorrhage were more frequently seen in CPPD patients. Interestingly, the in-hospital mortality was lower in the CPPD patients than the non-CPPD patients (OR: 0.77; CI 95 % 0.70-0.85). ACS in CPPD patients was associated with a longer mean length of stay than those without CPPD (OR: 3.35; 95 % CI 3.17-3.53). In addition, mean total charges were higher in the CPPD group (OR: 1.04; 95 % CI 1.01-1.10).

CONCLUSION

ACS in CPPD patients is associated with higher healthcare utilization, including cost and length of hospital stay, and lower in-hospital mortality than non-CPPD patients.

Describing calcium pyrophosphate deposition: undoing the tower of Babel!

PURPOSE OF REVIEW

In 1977, McCarty astutely observed, 'The variety of names suggested for the condition associated with deposits of calcium pyrophosphate dihydrate crystals is exceeded only by the variations of its clinical presentation'. Fast forward to 2024, a standardized nomenclature for calcium pyrophosphate deposition (CPPD) is still lacking. This review aims to delineate the challenges in characterizing CPPD through nomenclature and imaging.

RECENT FINDINGS

Despite the effort of nomenclature standardization in 2011 by the EULAR, confusion persists in the literature and clinical practice, with pseudo-forms and obscure abbreviations. The Gout, Hyperuricemia and Crystal-Associated Disease Network (G-CAN) has launched a project to redefine CPPD nomenclature and formulate a user-friendly language for effective communication with patients and other stakeholders. Additionally, recent advancements in imaging, have shed light on various aspects of the disorder.

SUMMARY

Almost 60 years from the first description of a clinical manifestation related to calcium pyrophosphate crystals, a common language describing the disorder is still lacking. A redefined CPPD nomenclature, together with lay-friendly terminology, would significantly contribute to the uniformity of CPPD research, enhance public understanding and awareness and improve doctor-patient communication and therefore disease outcomes. Imaging can provide deep insights into CPPD elements, promoting comprehension of this disorder.

[First classification criteria for diseases caused by calcium pyrophosphate deposition (CPPD)-Translation, explanation and assessment]

AIM

For diseases caused by calcium pyrophosphate deposition (CPPD), validated classification criteria were previously lacking. In this article the recently developed and validated classification criteria are translated, explained, and assessed.

METHODS

In recent years a multinational research group developed classification criteria for CPPD disease with the support by the European Alliance of Associations for Rheumatology (EULAR) and the American College of Rheumatology (ACR), following an established method. The developed criteria were finally validated in an independent cohort. The translation and annotation of the new first classification criteria were carried out in an iterative procedure in consensus with the authors.

RESULTS

The presence of a crowned dens syndrome or calcium pyrophosphate crystals in the synovial fluid in patients with pain, swelling or sensitivity of the joints (entry criterion) is sufficient for the classification as CPPD disease, where the symptoms cannot be completely explained by another rheumatic disease (exclusion criterion). If these symptoms are not present, a count of more than 56 points based on weighted criteria comprised of clinical features and the results of laboratory and imaging investigations can be included for classification as a CPPD disease. These criteria had a sensitivity of 92.2% and a specificity of 87.9% in the derivation cohorts (190 CPPD cases and 148 mimics), whereas the sensitivity was 99.2% and the specificity 92.5% in the validation cohorts (251 CPPD cases and 162 mimics).

CONCLUSION

The ACR/EULAR classification criteria 2023 of a CPPD disease will facilitate clinical research in this field. The use in the clinical routine will show how practical the criteria are.

Recent advances in the therapeutic management of calcium pyrophosphate deposition disease

Calcium pyrophosphate deposition (CPPD) disease is a form of crystal-induced arthropathy that arises from the accumulation of calcium pyrophosphate crystals within joints and soft tissues. This process leads to inflammation and damage to the affected joints. It can present asymptomatically or as acute or chronic inflammatory arthritis. Risk factors and comorbidities, including prior joint injury, osteoarthritis, hereditary or familial predisposition, and metabolic diseases, should be evaluated in CPPD cases. The management of CPPD remains a challenge in the sparsity of randomized controlled trials. The lack of such trials makes it difficult to establish evidence-based treatment protocols for CPPD. This review provides an overview of the current pharmacological management of CPPD, focusing on reducing inflammation, alleviating symptoms, and preventing acute flares. Non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids, and colchicine are effective in managing acute CPP arthritis. Colchicine may also be used prophylactically to prevent recurrent flares. In cases where other treatments have failed, anakinra, an interleukin-1 receptor antagonist, can be administered to alleviate acute flares. The management of chronic CPP inflammatory arthritis includes NSAIDs and/or colchicine, followed by hydroxychloroquine, low-dose glucocorticoids, and methotrexate, with limited data on efficacy. Tocilizumab can be used in refractory cases. In small studies, synovial destruction using intra-articular injection of yttrium 90 can decrease pain. To date, no disease-modifying therapies exist that reduce articular calcification in CPPD.