Features Associated With Different Inflammatory Phenotypes of Calcium Pyrophosphate Deposition Disease: 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.

Acute Severe Inflammatory Lumbar Spinal Pain Induced by Calcium Pyrophosphate Crystals: Computed Tomography Is Everything.

Acute back pain with neurological symptoms is a medical emergency. Here we report a case of severe degenerative spine disease with raised inflammatory markers due to an atypical cause.

The 2023 ACR/EULAR Classification Criteria for Calcium Pyrophosphate Deposition Disease.

OBJECTIVE: Calcium pyrophosphate deposition (CPPD) disease is prevalent and has diverse presentations, but there are no validated classification criteria for this symptomatic arthritis. The American College of Rheumatology (ACR) and EULAR have developed the first-ever validated classification criteria for symptomatic CPPD disease. METHODS: Supported by the ACR and EULAR, a multinational group of investigators followed established methodology to develop these disease classification criteria. The group generated lists of candidate items and refined their definitions, collected de-identified patient profiles, evaluated strengths of associations between candidate items and CPPD disease, developed a classification criteria framework, and used multi-criterion decision analysis to define criteria weights and a classification threshold score. The criteria were validated in an independent cohort. RESULTS: Among patients with joint pain, swelling, or tenderness (entry criterion) whose symptoms are not fully explained by an alternative disease (exclusion criterion), the presence of crowned dens syndrome or calcium pyrophosphate crystals in synovial fluid are sufficient to classify a patient as having CPPD disease. In the absence of these findings, a score >56 points using weighted criteria, comprising clinical features, associated metabolic disorders, and results of laboratory and imaging investigations, can be used to classify as CPPD disease. These criteria had a sensitivity of 92.2% and specificity of 87.9% in the derivation cohort (190 CPPD cases, 148 mimickers), whereas sensitivity was 99.2% and specificity was 92.5% in the validation cohort (251 CPPD cases, 162 mimickers). CONCLUSION: The 2023 ACR/EULAR CPPD disease classification criteria have excellent performance characteristics and will facilitate research in this field.

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

OBJECTIVE: Calcium pyrophosphate deposition (CPPD) disease is prevalent and has diverse presentations, but there are no validated classification criteria for this symptomatic arthritis. The American College of Rheumatology (ACR) and EULAR have developed the first-ever validated classification criteria for symptomatic CPPD disease. METHODS: Supported by the ACR and EULAR, a multinational group of investigators followed established methodology to develop these disease classification criteria. The group generated lists of candidate items and refined their definitions, collected de-identified patient profiles, evaluated strengths of associations between candidate items and CPPD disease, developed a classification criteria framework, and used multi-criterion decision analysis to define criteria weights and a classification threshold score. The criteria were validated in an independent cohort. RESULTS: Among patients with joint pain, swelling, or tenderness (entry criterion) whose symptoms are not fully explained by an alternative disease (exclusion criterion), the presence of crowned dens syndrome or calcium pyrophosphate crystals in synovial fluid are sufficient to classify a patient as having CPPD disease. In the absence of these findings, a score>56 points using weighted criteria, comprising clinical features, associated metabolic disorders, and results of laboratory and imaging investigations, can be used to classify as CPPD disease. These criteria had a sensitivity of 92.2% and specificity of 87.9% in the derivation cohort (190 CPPD cases, 148 mimickers), whereas sensitivity was 99.2% and specificity was 92.5% in the validation cohort (251 CPPD cases, 162 mimickers). CONCLUSION: The 2023 ACR/EULAR CPPD disease classification criteria have excellent performance characteristics and will facilitate research in this field.

A functional genomics approach reveals suggestive quantitative trait loci associated with combined TLR4 and BCP crystal-induced inflammation and osteoarthritis.

OBJECTIVE: Basic calcium phosphate (BCP) crystals can activate the NLRP3 inflammasome and are potentially involved in the pathogenesis of osteoarthritis (OA). In order to elucidate relevant inflammatory mechanisms in OA, we used a functional genomics approach to assess genetic variation influencing BCP crystal-induced cytokine production. METHOD: Peripheral blood mononuclear cells (PBMCs) were isolated from healthy volunteers who were previously genotyped and stimulated with BCP crystals and/or lipopolysaccharide (LPS) after which cytokines release was assessed. Cytokine quantitative trait locus (cQTL) mapping was performed. For in vitro validation of the cQTL located in anoctamin 3 (ANO3), PBMCs were incubated with Tamoxifen and Benzbromarone prior to stimulation. Additionally, we performed co-localisation analysis of our top cQTLs with the most recent OA meta-analysis of genome-wide association studies (GWAS). RESULTS: We observed that BCP crystals and LPS synergistically induce IL-1ß in human PBMCs. cQTL analysis revealed several suggestive loci influencing cytokine release upon stimulation, among which are quantitative trait locus annotated to ANO3 and GLIS3. As functional validation, anoctamin inhibitors reduced IL-1ß release in PBMCs after stimulation. Co-localisation analysis showed that the GLIS3 locus was shared between LPS/BCP crystal-induced IL-1ß and genetic association with Knee OA. CONCLUSIONS: We identified and functionally validated a new locus, ANO3, associated with LPS/BCP crystal-induced inflammation in PBMCs. Moreover, the cQTL in the GLIS3 locus co-localises with the previously found locus associated with Knee OA, suggesting that this Knee OA locus might be explained through an inflammatory mechanism. These results form a basis for further exploration of inflammatory mechanisms in OA.

Outcomes of COVID-19 in people with rheumatic and musculoskeletal disease in Ireland over the first 2 years of the pandemic.

BACKGROUND: Poor COVID-19 outcomes occur with higher frequency in people with rheumatic and musculoskeletal diseases (RMD). Better understanding of the factors involved is crucial to informing patients and clinicians regarding risk mitigation. AIM: To describe COVID-19 outcomes for people with RMD in Ireland over the first 2 years of the pandemic. METHODS: Data entered into the C19-GRA provider registry from Ireland between 24th March 2020 and 31st March 2022 were analysed. Differences in the likelihood of hospitalisation and mortality according to demographic and clinical variables were investigated. RESULTS: Of 237 cases included, 59.9% were female, 95 (41.3%) were hospitalised, and 22 (9.3%) died. Hospitalisation was more common with increasing age, gout, smoking, long-term glucocorticoid use, comorbidities, and specific comorbidities of cardiovascular and pulmonary disease, and cancer. Hospitalisation was less frequent in people with inflammatory arthritis and conventional synthetic or biologic disease-modifying antirheumatic drug use. Hospitalisation had a U-shaped relationship with disease activity, being more common in both high disease activity and remission. Mortality was more common with increasing age, gout, smoking, long-term glucocorticoid use, comorbidities, and specific comorbidities of cardiovascular disease, pulmonary disease, and obesity. Inflammatory arthritis was less frequent in those who died. CONCLUSION: Hospitalisation or death were more frequently experienced by RMD patients with increasing age, certain comorbidities including potentially modifiable ones, and certain medications and diagnoses amongst other factors. These are important 'indicators' that can help risk-stratify and inform the management of RMD patients.

Basic calcium phosphate crystals induce the expression of extracellular matrix remodelling enzymes in tenocytes.

OBJECTIVES: Basic calcium phosphate (BCP) crystals contribute to several syndromes associated with tendon disease, including acute calcific tendinitis and Milwaukee shoulder syndrome. Interactions between BCP crystals and tenocytes (tendon cells) may contribute to these clinical syndromes. This study aimed to determine the direct effects of BCP crystals on tenocyte function and viability. METHODS: In vitro assays were used to assess changes in human tenocytes cultured with BCP crystals. Real-time PCR was used to determine changes in the expression of tendon-related genes and extracellular matrix remodelling enzymes (MMPs; a disintegrin and metalloproteases, ADAMTS; and tissue inhibitor of metalloproteinases, TIMPs). ELISA was used to measure protein concentrations in tenocyte supernatants. MTT and alamarBlue™ assays were used to determine changes in cell viability. RESULTS: BCP crystals upregulated tenocyte gene expression of MMP-1, MMP-3, ADAMTS-4 and TIMP-1 after 24 h. Time-course experiments showed expression peaked at 8 h for TIMP-1 and 48 h for MMP-1 and ADAMTS-4. Cyclooxygenase (COX)-1 gene expression was upregulated after 48 h. Tenocytes did not alter expression of scleraxis and tendon collagens, and expression of pro-inflammatory cytokines was not induced with BCP crystals. BCP crystals increased tenocyte release of prostaglandin E2 (PGE2) and MMP-1 protein after 24 h. However, neither COX-1 inhibition nor COX-2 inhibition led to consistent change in BCP crystal-induced tenocyte gene expression of extracellular matrix remodelling enzymes. BCP crystals had no effect on tenocyte viability. CONCLUSION: BCP crystals induce extracellular matrix remodelling enzymes, but not inflammatory cytokines, in tenocytes.

Association of Gout Polygenic Risk Score With Age at Disease Onset and Tophaceous Disease in European and Polynesian Men With Gout.

OBJECTIVE: To determine whether a gout polygenic risk score (PRS) is associated with age at gout onset and tophaceous disease in European, East Polynesian, and West Polynesian men and women with gout. METHODS: A 19-variant gout PRS was produced in 7 European gout cohorts (N = 4,016), 2 East Polynesian gout cohorts (N = 682), and 1 West Polynesian gout cohort (N = 490). Sex-stratified regression models were used to estimate the relationship between the PRS and age at gout onset and tophaceous disease. RESULTS: The PRS was associated with earlier age at gout onset in men (ß = -3.61 in years per unit PRS [95% confidence interval (95% CI) -4.32, -2.90] in European men; ß = -6.35 [95% CI -8.91, -3.80] in East Polynesian men; ß = -3.51 [95% CI -5.46, -1.57] in West Polynesian men) but not in women (ß = 0.07 [95% CI -2.32, 2.45] in European women; ß = 0.20 [95% CI -7.21, 7.62] in East Polynesian women; ß -3.33 [95% CI -9.28, 2.62] in West Polynesian women). The PRS showed a positive association with tophaceous disease in men (odds ratio [OR] for the association 1.15 [95% CI 1.00, 1.31] in European men; OR 2.60 [95% CI 1.66, 4.06] in East Polynesian men; OR 1.53 [95% CI 1.07, 2.19] in West Polynesian men) but not in women (OR for the association 0.68 [95% CI 0.42, 1.10] in European women; OR 1.45 [95% CI 0.39, 5.36] in East Polynesian women). The PRS association with age at gout onset was robust to the removal of ABCG2 variants from the PRS in European and East Polynesian men (ß = -2.42 [95% CI -3.37, -1.46] and ß = -6.80 [95% CI -10.06, -3.55], respectively) but not in West Polynesian men (ß = -1.79 [95% CI -4.74, 1.16]). CONCLUSION: Genetic risk variants for gout also harbor risk for earlier age at gout onset and tophaceous disease in European and Polynesian men. Our findings suggest that earlier gout onset involves the accumulation of gout risk alleles in men but perhaps not in women, and that this genetic risk is shared across multiple ancestral groups.

An EDucation and eXercise intervention for gluteal tendinopathy in an Irish setting: a protocol for a feasibility randomised clinical trial (LEAP-Ireland RCT).

Background: Gluteal tendinopathy (GT) is a degenerative tendon condition characterised by pain over the greater trochanter of the hip. A randomised controlled trial (RCT) in Australia found that 14 sessions of EDucation on load management plus eXercise (EDX) delivered over 8 weeks resulted in greater improvements in global rating of change and pain outcomes at 8 and 52 weeks, compared with corticosteroid injection or 'wait and see'. Typically, 5-6 physiotherapy sessions are provided in public and private physiotherapy settings in Ireland, therefore, the aim of this study is to examine the feasibility of conducting a future definitive RCT to investigate effectiveness of 6 sessions of the EDX programme compared to usual care. Methods: We will randomly allocate 64 participants with GT to physiotherapist-administered EDX or usual care. The EDX intervention (EDX-Ireland) will be delivered in 6 sessions over 8 weeks.To determine feasibility of an RCT, we will assess recruitment and retention and outcome measure completion. The health status outcomes to be assessed at baseline, 8 weeks and 3 months include: Global Rating of Change, pain severity, the Victorian Institute of Sport Assessment-Gluteal Questionnaire (VISA-G), the Patient-Specific Functional Scale, the Pain Catastrophizing Scale, Patient Health Questionnaire (PHQ), Pain Self-Efficacy Questionnaire, the EQ-5D-5L, the Central Sensitisation Inventory and hip abductor muscle strength. We will explore acceptability of the EDX-Ireland intervention from the perspective of patients and treatment providers, and the perspective of referrers to the trial. A Study Within A Trial will be also applied to compare recording of exercise adherence using app-based technology to paper diaries. Discussion: There is a need to establish effective treatments for GT that potentially can be implemented into existing health systems. The findings of this feasibility trial will inform development of a future definitive RCT. Registration: The trial is registered prospectively on ClinicalTrials.gov ( NCT05516563, 27/10/2022).

Colchicine twice a day for hand osteoarthritis (COLOR): a double-blind, randomised, placebo-controlled trial.

BACKGROUND: Colchicine has been suggested for osteoarthritis treatment, but evidence is contradictory. We aimed to investigate colchicine's efficacy and safety compared with placebo in people with hand osteoarthritis. METHODS: In this single-centre, double-blind, randomised, placebo-controlled trial we recruited adults with symptomatic hand osteoarthritis and finger pain of at least 40 mm on a 100 mm visual analogue scale from an outpatient clinic in Denmark. The hand with the most severe finger pain at inclusion was the target hand. Participants were randomly assigned (1:1) to 0·5 mg colchicine or placebo taken orally twice a day for 12 weeks, stratified by BMI (≥30 kg/m2), sex, and age (≥75 years). Participants, outcome assessors, and data analysts were masked to treatment allocation. The primary endpoint was change from baseline to week 12 in target hand finger pain, assessed on a 100 mm visual analogue scale with a pre-specified minimal clinically important difference of 15 mm, in the intention-to-treat population. Safety was assessed at week 12 in the intention-to-treat population. The study was registered with ClinicalTrials.gov, NCT04601883, and with EudraCT, 2020-002803-20. FINDINGS: Between Jan 15, 2021, and March 3, 2022, 186 people were screened for eligibility, and 100 were randomly assigned to receive colchicine (n=50) or placebo (n=50). Participants had a mean age of 70·9 (SD 7·5) years, 69 (69%) of 100 were women and 31 (31%) were men. All participants completed the study. The mean change from baseline to week 12 in finger pain were -13·9 mm (SE 2·8) in the colchicine group and -13·5 mm (2·8) in the placebo group, with a between-group difference (colchicine vs placebo) of -0·4 mm (95% CI -7·6 to 6·7; p=0·90). In the colchicine group, there were 76 adverse events in 36 (72%) of 50 participants and one serious adverse advent (migraine attack leading to hospital admission). In the placebo group, there were 42 adverse events in 22 (44%) of 50 participants and two serious adverse events (cholecystitis and elevated alanine aminotransferase concentrations, in the same patient). INTERPRETATION: In people with painful hand osteoarthritis, treatment with 0·5 mg of colchicine twice day for 12 weeks did not effectively relieve pain, and treatment with colchicine was associated with more adverse events. FUNDING: The Oak Foundation, IMK Almene Fond, Minister Erna Hamilton's Scholarship for Science and Art, AP Moller and Wife Chastine McKinney Moller's Foundation for Medical Science Advancement, The Danish Medical Association, the Velux Foundation, Aase and Ejnar Danielsen's Foundation, and Director Emil C Hertz and Wife Inger Hertz's foundation.

Sensory Perception Quotient Reveals Visual, Scent and Touch Sensory Hypersensitivity in People With Fibromyalgia Syndrome.

Background: Environmental sensitivity is commonly reported by people with fibromyalgia syndrome. People living with fibromyalgia syndrome frequently report hypersensitivity to noxious and non-noxious sensations. To date, there has been little empirical validation of sensory disturbance to non-noxious triggers. Environmental sensitivity is used as a diagnostic feature only in Bennet's alternative criteria for diagnosis of fibromyalgia, where it was ranked the second most important of the components for diagnosis, after number of pain sites. The aim of this study was to use a validated sensory measure to determine if people with fibromyalgia have greater sensory disturbances compared to people with other chronic pain conditions. Methods: This study used the Sensory Perception Quotient (SPQ) 92 question survey in adults with chronic pain conditions. A fibromyalgia group (n = 135) and a non-fibromyalgia chronic pain control group (n = 45) were recruited. All participants completed the SPQ as a self-report measure of sensory processing. In addition to the original SPQ scoring method, the Revised Scoring of the Sensory Perception Quotient (SPQ-RS) method was used to investigate self-reported hypersensitivity and hyposensitivity and the vision, hearing, taste, touch, and smell subscales. Chi-squared tests were used for categorical variables and Mann Whitney U, or Kruskal-Wallis H test were used to compare groups. Results: The fibromyalgia group reported significantly more sensitivity compared to the control group (p = 0.030). The fibromyalgia group reported significantly greater hypersensitivity (p = 0.038), but not more hyposensitivity (p = 0.723) compared to controls. The average fibromyalgia SPQ score (92.64 ± 23.33) was similar to that previously reported for adults with autism (92.95 ± 26.61). However, whereas adults with autism had broad range hypersensitivity, the fibromyalgia group reported significantly more hypersensitivity compared to the control group, but the range was restricted to vision (p = 0.033), smell (p = 0.049) and touch (0.040). Conclusions: These findings demonstrate greater sensory hypersensitivity in people with fibromyalgia compared to people with other chronic pain disorders. Greater hypersensitivity was restricted to touch, vision, and smell, all of which have previously been demonstrated to crosstalk with nociception.

Temporal trends in COVID-19 outcomes in people with rheumatic diseases in Ireland: data from the COVID-19 Global Rheumatology Alliance registry.

OBJECTIVES: Although evidence is accumulating globally, data on outcomes in rheumatic disease and COVID-19 in Ireland are limited. We used data from the COVID-19 Global Rheumatology Alliance (C19-GRA) to describe time-varying COVID-19 outcomes for people with rheumatic disease in Ireland. METHODS: Data entered into the C19-GRA provider registry from Ireland between 24 March 2020 and 9 July 2021 were analysed. Differences in the likelihood of hospitalization and mortality according to demographic and clinical variables were investigated using Chi-squared test or Fisher's exact test, as appropriate. Trends in odds of hospitalization and mortality over time were investigated using logistic regression with the time period as a categorical variable. RESULTS: Of 212 cases included, 59.4% were female and median age was 58.0 years (range 13-96). Of the 212 cases, 92 (43%) were hospitalized and 22 (10.4%) died. Increasing age, a diagnosis of gout, ever smoking, glucocorticoid use, having comorbidities and specific comorbidities of cancer, cardiovascular and pulmonary disease were more common in those hospitalized. A diagnosis of inflammatory arthritis, csDMARD and/or b/tsDMARD use were less frequent in those hospitalized. Increasing age, a diagnosis of gout, ever smoking, having comorbidities and specific comorbidities of obesity, cardiovascular and pulmonary disease were more common in those who died. Odds of hospitalization or mortality did not change over time. CONCLUSION: No temporal trend was observed in either COVID-19-related hospitalization or mortality outcomes for people with rheumatic disease in Ireland.

Identifying Potential Classification Criteria for Calcium Pyrophosphate Deposition Disease: Item Generation and Item Reduction.

OBJECTIVE: Classification criteria for calcium pyrophosphate deposition (CPPD) disease will facilitate clinical research on this common crystalline arthritis. Our objective was to report on the first 2 phases of a 4-phase process for developing CPPD classification criteria. METHODS: CPPD classification criteria development is overseen by a 12-member steering committee. Item generation (phase I) included a scoping literature review of 5 literature databases and contributions from a 35-member combined expert committee and 2 patient research partners. Item reduction and refinement (phase II) involved a combined expert committee meeting, discussions among clinical, imaging, and laboratory advisory groups, and an item-rating exercise to assess the influence of individual items toward classification. The steering committee reviewed the modal rating score for each item (range -3 [strongly pushes away from CPPD] to +3 [strongly pushes toward CPPD]) to determine items to retain for future phases of criteria development. RESULTS: Item generation yielded 420 items (312 from the literature, 108 from experts/patients). The advisory groups eliminated items that they agreed were unlikely to distinguish between CPPD and other forms of arthritis, yielding 127 items for the item-rating exercise. Fifty-six items, most of which had a modal rating of +/- 2 or 3, were retained for future phases. As numerous imaging items were rated +3, the steering committee recommended focusing on imaging of the knee and wrist and 1 additional affected joint for calcification suggestive of CPP crystal deposition. CONCLUSION: A data- and expert-driven process is underway to develop CPPD classification criteria. Candidate items comprise clinical, imaging, and laboratory features.

Serum urate as a proposed surrogate outcome measure in gout trials: From the OMERACT working group.

Serum urate (SU) is the most common primary efficacy outcome in trials of urate-lowering therapies for gout. Despite this, it is not formally considered a validated surrogate outcome. In this paper we will outline the definitions of biomarkers and surrogate outcome measures, respectively as well as the available frameworks and challenges in the assessment of the validity of serum urate as a surrogate in gout (i.e. a reasonable replacement for gout symptoms).

Predictors of hospitalization in patients with rheumatic disease and COVID-19 in Ireland: data from the COVID-19 global rheumatology alliance registry.

OBJECTIVES: Given the limited data regarding the risk of hospitalization in patients with rheumatic disease and coronavirus disease 2019 (COVID-19) in Ireland, we used the COVID-19 Global Rheumatology Alliance (GRA) registry data to study outcomes and their predictors. The primary objective was to explore potential predictors of hospitalization. METHODS: We examined data on patients and their disease-related characteristics entered in the COVID-19 GRA provider registry from Ireland (from 24 March 2020 to 31 August 2020). Multivariable logistic regression was used to assess the association of demographic and clinical characteristics with hospitalization. RESULTS: Of 105 patients, 47 (45.6%) were hospitalized and 10 (9.5%) died. Multivariable logistic regression analysis showed that age [odds ratio (OR) = 1.06, 95% CI 1.01, 1.10], number of co-morbidities (OR = 1.93, 95% CI 1.11, 3.35) and glucocorticoid use (OR = 15.01, 95% CI 1.77, 127.16) were significantly associated with hospitalization. A diagnosis of inflammatory arthritis was associated with lower odds of hospitalization (OR = 0.09, 95% CI 0.02, 0.32). CONCLUSION: Increasing age, co-morbidity burden and glucocorticoid use were associated with hospitalization, whereas a diagnosis of inflammatory arthritis was associated with lower odds of hospitalization.

Towards development of core domain sets for short term and long term studies of calcium pyrophosphate crystal deposition (CPPD) disease: A framework paper by the OMERACT CPPD working group.

INTRODUCTION: Although calcium pyrophosphate deposition (CPPD) is common, there are no published outcome domains or validated measurement instruments for CPPD studies. In this paper, we describe the framework for development of the Outcome Measures in Rheumatology (OMERACT) CPPD Core Domain Sets. METHODS: The OMERACT CPPD working group performed a scoping literature review and qualitative interview study. Generated outcomes were presented at the 2020 OMERACT CPPD virtual Special Interest Group (SIG) meeting with discussion focused on whether different core domain sets should be developed for different calcium pyrophosphate deposition (CPPD) clinical presentations and how the future CPPD Core Domain Set may overlap with already established osteoarthritis (OA) domains. These discussions informed development of a future work plan for development of the OMERACT CPPD Core Domain Sets. FINDINGS: Domains identified from a scoping review of 112 studies and a qualitative interview study of 36 people (28 patients with CPPD, 7 health care professionals, one stakeholder) were mapped to core areas of OMERACT Filter 2.1. The majority of SIG participants agreed there was need to develop separate core domain sets for "short term" and "long term" studies of CPPD. Although CPPD + OA is common and core domain sets for OA have been established, participants agreed that existing OA core domain sets should not influence the development of OMERACT core domain sets for CPPD. Prioritization exercises (using Delphi methodology) will consider 40 potential domains for short term studies of CPPD and 47 potential domains for long term studies of CPPD. CONCLUSION: Separate OMERACT CPPD Core Domain Sets will be developed for "short term" studies for an individual flare of acute CPP crystal arthritis and for "long term" studies that may include participants with any clinical presentation of CPPD (acute CPP crystal arthritis, chronic CPP crystal inflammatory arthritis, and/or CPPD + OA).

Flare Rate Thresholds for Patient Assessment of Disease Activity States in Gout.

OBJECTIVE: To determine the relationship between gout flare rate and self-categorization into remission, low disease activity (LDA), and patient acceptable symptom state (PASS). METHODS: Patients with gout self-categorized as remission, LDA, and PASS, and reported number of flares over the preceding 6 and 12 months. Multinomial logistic regression was used to determine the association between being in each disease state (LDA and PASS were combined) and flare count, and self-reported current flare. A distribution-based approach and extended Youden index identified possible flare count thresholds for each state. RESULTS: Investigators from 17 countries recruited 512 participants. Remission was associated with a median recalled flare count of zero over both 6 and 12 months. Each recalled flare reduced the likelihood of self-perceived remission compared with being in higher disease activity than LDA/PASS, by 52% for 6 months and 23% for 12 months, and the likelihood of self-perceived LDA/PASS by 15% and 5% for 6 and 12 months, respectively. A threshold of 0 flares in preceding 6 and 12 months was associated with correct classification of self-perceived remission in 58% and 56% of cases, respectively. CONCLUSION: Flares are significantly associated with perceptions of disease activity in gout, and no flares over the prior 6 or 12 months is necessary for most people to self-categorize as being in remission. However, recalled flare counts alone do not correctly classify all patients into self-categorized disease activity states, suggesting that other factors may also contribute to self-perceived gout disease activity.

Systematic genetic analysis of early-onset gout: ABCG2 is the only associated locus.

OBJECTIVE: The aim of this study was to examine whether serum urate-associated genetic variants are associated with early-onset gout. METHODS: Participants with gout in the Genetics of Gout in Aotearoa study with available genotyping were included (n = 1648). Early-onset gout was defined as the first presentation of gout <40 years of age. Single nucleotide polymorphisms (SNPs) for the 10 loci most strongly associated with serum urate were genotyped. Allelic association of the SNPs with early-onset gout was tested using logistic regression in an unadjusted model and in a model adjusted for sex, body mass index, tophus presence, flare frequency, serum creatinine and highest serum urate. The analysis was also done in two replication cohorts: Eurogout (n = 704) and Ardea (n = 755), and data were meta-analysed. RESULTS: In the Genetics of Gout in Aotearoa study, there were 638 (42.4%) participants with early-onset gout. The ABCG2 rs2231142 gout risk T-allele was present more frequently in participants with early-onset gout compared with the later-onset group. For the other SNPs tested, no differences in risk allele number were observed. In the allelic association analysis, the ABCG2 rs2231142 T-allele was associated with early-onset gout in unadjusted and adjusted models. Analysis of the replication cohorts confirmed the association of early-onset gout with the ABCG2 rs2231142 T-allele, but not with other serum urate-associated SNPs. In the meta-analysis, the odds ratio (95% CI) for early-onset gout for the ABCG2 rs2231142 T-allele was 1.60 (1.41, 1.83). CONCLUSION: In contrast to other serum urate-raising variants, the ABCG2 rs2231142 T-allele is strongly associated with early-onset gout.