Still's disease continuum from childhood to elderly: data from the international AIDA Network Still's disease registry

Unmet needs and research gaps in Still's disease across ages: proceedings from a pediatric and adult joint expert panel

BACKGROUND

Still's disease (SD), including systemic juvenile idiopathic arthritis (sJIA) and adult-onset SD (AOSD), is an inflammatory condition typically characterized by daily fever, arthritis, and skin rash together with neutrophilic leukocytosis, thrombocytosis, and increased acute phase reactants. The reported differences between sJIA and AOSD appear to reflect variations along an inflammatory spectrum influenced by age, rather than differences in the underlying pathology.

METHODS

In February 2023, an expert meeting, including pediatric and adult rheumatologists, was held in Rome, Italy, with the aim of defining more precise and timely strategies for disease management. The following four topics were discussed: (1) early recognition and diagnosis of SD; (2) pathogenetic pathways and possible biomarkers for diagnosis and response; (3) refractory disease and risk factors, and (4) treatment of SD and its complications.

RESULTS

The development of improved diagnostic criteria and validation of biomarkers are important steps towards achieving early diagnosis, although several biomarkers remain to be universally validated and available for clinical practice. Additionally, awareness of important complications of SD, including macrophage activation syndrome and lung disease, is crucial for improving patient outcomes, alongside an improved understanding of risk factors for the development of refractory disease. While interleukin (IL)-1 and IL-6 inhibitors have improved the treatment landscape of SD, harmonizing the therapeutic approach across centers and countries, together with developing treatment strategies for refractory patients, still represents a challenge.

CONCLUSIONS

Here, we summarize the results of discussions among experts, supplemented by relevant literature, and highlight unmet needs in the diagnosis and management of SD.

First-line biological versus conventional synthetic disease-modifying antirheumatic drug therapy in adult-onset Still's disease: a multicentre, retrospective, propensity weighted cohort study

BACKGROUND

Data on the efficacy of biological disease-modifying antirheumatic drug (DMARD) therapies such as anakinra, canakinumab, and tocilizumab as a primary therapeutic option in adult-onset Still's disease (AOSD) are scarce, and treatment recommendations rely mainly on data extrapolated from paediatric studies. The aim of this study was to compare the effectiveness of first-line biological DMARD therapy versus conventional synthetic DMARD therapy in AOSD.

METHODS

This multicentre, retrospective, propensity weighted cohort study was done at 16 secondary and tertiary rheumatology centres across Germany. Eligible patients were diagnosed with AOSD, met the Yamaguchi classification criteria, and had active disease without current treatment. All patients had documented follow-up assessments at weeks 12 and 72. The primary endpoint was sustained, event-free remission; a combined endpoint of sustained remission (C-reactive protein <10 mg/L and no arthritis, rash, or fever) and absence of complications during follow up in patients treated with first-line biological DMARDs (with or without glucocorticoids) or conventional synthetic DMARDs (methotrexate or glucocorticoids). Analysis was by propensity score weighted logistic regression, thereby balancing for the initial Pouchot score, ferritin concentration, and age and sex differences between groups. Analysis was done in the per protocol population. People with lived experience were not involved in the study design. The study is registered with the ISRCTN registry, ISRCTN86135778.

FINDINGS

Between Jan 1, 2007, and Sep 30, 2022, we screened 228 patients for inclusion. 142 patients were excluded, and 86 patients with AOSD who had an incident diagnosis or a flare without any maintenance treatment including glucocorticoids were enrolled and included in our analysis. 50 (58%) of 86 patients were female, 36 (42%) were male, and 84 (98%) were White. The mean age at inclusion was 39·4 years (SD 15·4). 44 (51%) of 86 had received a first-line biological DMARD and 42 (49%) received a first-line conventional synthetic DMARD. Biological DMARD therapy was associated with a greater likelihood of reaching the primary endpoint of sustained, event-free remission (OR 7·20, 95% CI 2·50-36·64; p=0·0007). At week 72, the rate of sustained, event-free remission was 50% (95% CI 34-65%; n=21) in the first-line biological DMARD group and 12% (3-23%; n=5) in the first-line conventional synthetic group. Glucocorticoid-related complications were more often described in the first-line conventional synthetic DMARD group (new-onset arterial hypertension [n=2] and glucocorticoid-related skin diseases [n=3]) versus none in the first-line biological DMARD group). Three (7%) of 42 patients in the conventional synthetic DMARD group died (two from macrophage activation syndrome, one unknown cause) versus none in the first-line biological DMARD group.

INTERPRETATION

First-line biological DMARD therapy in patients with AOSD showed a statistically significant association with sustained, event-free remission and fewer complications. Our findings highlight the potential of biologics to improve patient outcomes compared with conventional treatment options in AOSD.

FUNDING

None.

Evaluation of Myocarditis in Patients With Still Disease: Clinical Findings From the Multicenter International AIDA Network Still Disease Registry

OBJECTIVE

We aimed to (1) evaluate the cardiac involvement, with a focus on myocarditis, in patients with Still disease included in the multicenter Autoinflammatory Disease Alliance (AIDA) Network Still disease registry; and (2) assess the predictive factors for myocarditis by deriving a clinical risk patient profile for this severe manifestation.

METHODS

A multicenter observational study was established, in which consecutive patients with Still disease in the AIDA Network Still disease registry were characterized by cardiac involvement. Cardiac involvement was defined according to the presence of pericarditis, tamponade, myocarditis, and/or aseptic endocarditis.

RESULTS

In total, 73 patients with Still disease and cardiac involvement were assessed (mean age 36.3 [SD 19.9] years; male sex, 42.5%), out of which 21.9% were children. The most common cardiac manifestation was pericarditis, occurring in 90.4% of patients; patients also presented with myocarditis (26%), and less frequently endocarditis (2.7%) and tamponade (1.4%). In comparing clinical features of patients with myocarditis to those without, significantly increased frequencies of skin rash and pleuritis, as well as higher systemic scores, were seen. Further, a higher mortality rate was shown in patients with myocarditis. In regression models, skin rash and the systemic score independently predicted the myocarditis.

CONCLUSION

The characteristics of patients with Still disease and cardiac involvement were assessed in the AIDA Network. The most common feature was the pericarditis, but a more severe clinical picture was also reported in patients with myocarditis. The latter was associated with increased mortality rate and higher systemic score, identifying patients who should be carefully managed.

Advancing personalised precision treatment for Still's disease based on molecular characteristics and disease progression

Still's disease, a systemic autoinflammatory disorder with a classic multigenetic background, is characterised by polyarthritis, high-spiking fever, salmon-like evanescent skin rash, and hyperferritinaemia. Although the exact cause of Still's disease remains unclear, it is believed to be influenced by genetic factors, infections, and immune dysregulation. Current studies indicate that neutrophils and macrophages play crucial roles in the pathogenesis of Still's disease, along with involvement of natural killer cells, T cells, and B cells. Advances in biologic agents have expanded treatment strategies beyond conventional approaches, with cytokine-targeted agents showing promise in the management of Still's disease. Some cytokine-targeting biologic agents can be developed based on clinical manifestations, complications, immune cells, and molecular networks. Emphasis of immunophenotyping for precise clinical subtyping and targeted molecular therapies based on these findings is crucial for optimising treatment outcomes. In this Review, we discuss the latest advancements in the understanding of Still's disease pathogenesis and corresponding therapeutic approaches.

Non-Classical Complications of Adult-Onset Still's Disease: A Multicenter Spanish Study

Objective: To investigate the prevalence and clinical spectrum of atypical or non-classical complications in adult-onset Still's disease (AOSD) beyond macrophage activation syndrome (MAS) and to identify factors linked to their occurrence. Methods: Multicenter cross-sectional study of AODS cases included in the Spanish registry on Still's disease. Results: This study included 107 patients (67% women), of whom 64 (59.8%) developed non-classical complications. These include macrophage activation syndrome in 9.5%, atypical skin manifestations in 38.8%, cardiac involvement in 22.7% (comprising pericarditis, myocarditis, pulmonary arterial hypertension, and noninfectious endocarditis), pleuritis in 28.9%, transient pulmonary infiltrates in 4%, significant headache in 14.1%, lower abdominal pain with evidence of peritonitis in 8.4%, and secondary amyloidosis in 0.9%. In the multivariate logistic regression analysis, lymphadenopathy (OR 2.85, 95% CI 1.03-7.91, p = 0.044) and the systemic score system (SSC) index (OR 1.86, 95% CI 1.29-2.69, p = 0.001) were independently associated with the development of non-classical clinical manifestations. In contrast, typical exanthema was associated with a reduced risk of these complications (OR 0.32, 95% CI 0.11-0.95, p = 0.041). Conclusions: In addition to the typical clinical manifestations and MAS, a significant proportion of patients with AOSD develop uncommon complications, some of which can be potentially life-threatening. These should be considered in the evaluation and follow-up of patients. Early recognition and prompt management are crucial to significantly reduce morbidity and mortality.

Efficacy and safety of biologic drugs in Still's disease: a systematic review and network meta-analysis of randomized controlled trials

OBJECTIVES

Still's disease is a rare autoinflammatory disorder characterized by systemic inflammation, fever, rash and arthritis. The term 'Still's disease' covers the paediatric subtype systemic juvenile idiopathic arthritis (sJIA) and adult-onset Still's disease (AOSD), which affects adults. Biologic drugs, including the anti-IL-1 agents anakinra, canakinumab and rilonacept and the IL-6 antagonist tocilizumab, are used in the management of Still's disease.

METHODS

We conducted a systematic review and network meta-analysis of randomized controlled trials, and the study protocol was registered in PROSPERO (CRD42023450442). MEDLINE, EMBASE and CENTRAL were screened from inception until 17 September 2023. We included patients with Still's disease who received placebo or biologic drugs: anakinra, canakinumab, rilonacept or tocilizumab. The primary efficacy and safety outcomes were achievement of ACR50 response and occurrence of serious adverse events, respectively. The interventions were ranked using rankograms and SUCRA values.

RESULTS

Nine trials with 430 patients were included. All biologic drugs were associated with greater odds of ACR50 response compared with placebo. There was no statistically significant association between biologic drugs and serious adverse events. The multivariate meta-analysis found no difference between biologic drugs. As per SUCRA rankings, anakinra was the most effective and safe option with respect to ACR50 response and occurrence of serious adverse events.

CONCLUSION

This is the first systematic review and meta-analysis to assess the efficacy and safety of biologic drugs in paediatric and adult patients with Still's disease. Biologic drugs were effective in achieving ACR response and demonstrated a low adverse event profile in the management of Still's disease.

Serum interleukin-18 levels can improve the diagnostic performance of the PRINTO and ILAR criteria for systemic juvenile idiopathic arthritis

OBJECTIVE

Recently, the Pediatric Rheumatology International Trials Organization (PRINTO) has proposed revisions to the current International League of Associations for Rheumatology (ILAR) criteria for systemic juvenile idiopathic arthritis (s-JIA). Interleukin (IL)-18 overproduction plays a significant role in the pathogenesis of s-JIA. This study aimed to evaluate the performance of the PRINTO criteria compared with the ILAR criteria and determine whether serum IL-18 levels improve their diagnostic performances.

METHODS

Overall, 90 patients with s-JIA and 27 patients with other febrile disease controls presenting with a prolonged fever of > 14 days and arthritis and/or erythematous rash were enrolled. The ILAR and PRINTO classification criteria were applied to all patients and examined with expert diagnoses. Enzyme-linked immunosorbent assay was used for measuring serum IL-18 levels.

RESULTS

The PRINTO criteria had higher sensitivity but lower specificity than the ILAR criteria (sensitivity: PRINTO 0.856, ILAR 0.533; specificity: PRINTO 0.259, ILAR 0.851). With the addition of serum IL-18 levels ≥ 4,800 pg/mL, the sensitivity of the ILAR criteria and specificity of the PRINTO criteria were improved to 1.000 and 1.000, respectively. PRINTO plus serum IL-18 levels ≥ 4,800 pg/mL showed the highest value in Youden's index (sensitivity - [1 - specificity]).

CONCLUSION

Serum IL-18 levels could improve the diagnostic performance of the PRINTO and ILAR criteria for s-JIA. The PRINTO criteria plus serum IL-18 levels ≥ 4,800 pg/mL could be the best diagnostic performance for s-JIA.

Still's Disease Onset in Older Adults: Clinical Features, Diagnosis, and Management

Still's disease (SD) is a rare systemic inflammatory disease that is characterized by high fever, polyarthritis, and an evanescent rash as its main symptoms but that may also be complicated by pleuritis and macrophage activation syndrome (MAS). There has been a recent increase in studies on older-onset SD, which presents with less-typical clinical features, such as sore throat, skin lesions, and splenomegaly, but more complications including pleuritis and disseminated intravascular coagulation. Several reports have shown higher levels of inflammatory markers, including serum ferritin, and poorer outcomes in terms of survival and drug-free remission in older patients. In addition, caution is needed when diagnosing SD in older patients because of the increased incidence of differential diagnoses such as infectious diseases, malignancies, and inflammatory diseases. Prognosis is poor in older patients, and treatment-associated infections and severe complications such as MAS are the main cause of mortality. The use of biologics and treatment response may not differ greatly between older and younger patients. Although the data are limited, anti-IL-1 and anti-IL-6 agents may control SD in these patients with careful use and adequate infection prevention. Recent studies that classified adult-onset SD by cluster analysis or latent class analysis showed that older patients form a unique cluster of SD, indicating the need for clinicians to pay more attention to the diagnosis and management of SD in older patients.

The Systemic Score May Identify Life-Threatening Evolution in Still Disease: Data from the GIRRCS AOSD-Study Group and the AIDA Network Still Disease Registry

OBJECTIVE

We aimed to evaluate the clinical usefulness of the systemic score in the prediction of life-threatening evolution in Still disease. We also aimed to assess the clinical relevance of each component of the systemic score in predicting life-threatening evolution and to derive patient subsets accordingly.

METHODS

A multicenter, observational, prospective study was designed including patients included in the Gruppo Italiano Di Ricerca in Reumatologia Clinica e Sperimentale Adult-Onset Still Disease Study Group and the Autoinflammatory Disease Alliance Network Still Disease Registry. Patients were assessed to see if the variables to derive the systemic score were available. The life-threatening evolution was defined as mortality, whatever the clinical course, and/or macrophage activation syndrome, a secondary hemophagocytic lymphohistiocytosis associated with a poor prognosis.

RESULTS

A total of 597 patients with Still disease were assessed (mean ± SD age 36.6 ± 17.3 years; male 44.4%). The systemic score, assessed as a continuous variable, significantly predicted the life-threatening evolution (odds ratio [OR] 1.24; 95% confidence interval [CI] 1.07-1.42; P = 0.004). A systemic score ≥7 also significantly predicted the likelihood of a patient experiencing life-threatening evolution (OR 3.36; 95% CI 1.81-6.25; P < 0.001). Assessing the clinical relevance of each component of the systemic score, liver involvement (OR 1.68; 95% CI 1.48-2.67; P = 0.031) and lung disease (OR 2.12; 95% CI 1.14-4.49; P = 0.042) both significantly predicted life-threatening evolution. The clinical characteristics of patients with liver involvement and lung disease were derived, highlighting their relevance in multiorgan disease manifestations.

CONCLUSION

The clinical utility of the systemic score was shown in identifying Still disease at a higher risk of life-threatening evolution in a large cohort. Furthermore, the clinical relevance of liver involvement and lung disease was highlighted.

Recent advances and evolving concepts in Still's disease

Still's disease is a rare inflammatory syndrome that encompasses systemic juvenile idiopathic arthritis and adult-onset Still's disease, both of which can exhibit life-threatening complications, including macrophage activation syndrome (MAS), a secondary form of haemophagocytic lymphohistiocytosis. Genetic insights into Still's disease involve both HLA and non-HLA susceptibility genes, suggesting the involvement of adaptive immune cell-mediated immunity. At the same time, phenotypic evidence indicates the involvement of autoinflammatory processes. Evidence also implicates the type I interferon signature, mechanistic target of rapamycin complex 1 signalling and ferritin in the pathogenesis of Still's disease and MAS. Pathological entities associated with Still's disease include lung disease that could be associated with biologic DMARDs and with the occurrence of MAS. Historically, monophasic, recurrent and persistent Still's disease courses were recognized. Newer proposals of alternative Still's disease clusters could enable better dissection of clinical heterogeneity on the basis of immune cell profiles that could represent diverse endotypes or phases of disease activity. Therapeutically, data on IL-1 and IL-6 antagonism and Janus kinase inhibition suggest the importance of early administration in Still's disease. Furthermore, there is evidence that patients who develop MAS can be treated with IFNγ antagonism. Despite these developments, unmet needs remain that can form the basis for the design of future studies leading to improvement of disease management.

The latest advances in the use of biological DMARDs to treat Still's disease

INTRODUCTION

Currently, the therapeutic management of Still's disease, a multisystemic inflammatory rare disorder, is directed to target the inflammatory symptoms and signs of patients. The treatment varies from glucocorticoids to disease-modifying antirheumatic drugs (DMARDs), both conventional synthetic and biological (bDMARDs). Usually, in refractory patients, bDMARDs are administered.

AREAS COVERED

Among bDMARDs, IL-1 and IL-6 inhibitors are frequently used, as data reported from both clinical trials and 'real-life' experiences. Recently, innovative therapeutic strategies have suggested an early administration of bDMARDs to increase the rate of clinical response and drug-free remission. Some new targets have been also proposed targeting IL-18, IFN-γ, and JAK/STAT pathway, which could be applied to Still's disease and its life-threatening evolution.

EXPERT OPINION

Many lines of evidence improved the knowledge about the therapeutic management of Still's disease with bDMARDs. However, many unmet needs may be still highlighted which could provide the basis to arrange further specific research in increasing the rate of clinical response. In fact, Still's disease remains a highly heterogeneous disease suggesting possible diverse underlying pathogenic mechanisms, at least partially, and consequent different therapeutic strategies. A better patient stratification may help in arranging specific studies to improve the long-term outcome of Still's disease.