Hyperferritinemia: Important Differentials for the Rheumatologists.

Ferritin is commonly used as a marker for iron status, aiding in diagnosing iron deficiency anemia. However, it is also an acute phase reactant often elevated in various inflammatory conditions. Marked hyperferritinemia, defined as ferritin levels above 10,000 µg/L, can indicate severe underlying conditions, including infections, cardiovascular like heart failure, endocrinological, autoimmune, and malignancies. This case report highlights the differential diagnoses and clinical implications of hyperferritinemia from a rheumatological perspective. Here are two case reports illustrating the use of ferritin in aiding the diagnosing of two uncommon conditions: adult-onset Still's disease (AOSD) and hemophagocytic lymphohistiocytosis (HLH). The first case involves a 37-year-old male who presented with a pruritic rash, flu-like symptoms, joint pain, fever, and chills. Despite multiple emergency department (ED) visits, his hyperferritinemia reached 88,000 µg/L, and he met the Yamaguchi criteria for AOSD. Treatment with pulse-dose steroids led to a rapid resolution of symptoms. In the second case, a 50-year-old female presented with sepsis due to recurrent axillary skin infections, needing transfer to the intensive care unit. Laboratory findings revealed hyperferritinemia of 39,671 µg/L, crucial for distinguishing between rheumatological and hematological causes. Further investigation revealed diffuse large B-cell lymphoma. Tragically, the patient succumbed to her illness. The cases highlight the critical role of ferritin as a marker for underlying severe conditions. The clinical interpretation of ferritin levels and appropriate diagnostic workup are essential in identifying and managing these conditions to reduce morbidity and mortality. Ferritin levels should not be overlooked as merely an indicator of iron status or inflammation. Marked hyperferritinemia requires thorough investigation to differentiate between potential underlying conditions that may allow for more prompt recognition and management to reduce morbidity and mortality.

Identification of novel cytokine to judge the diagnosis and clinical phenotype of adult-onset Still's disease.

This study aimed to identify biomarkers to distinguish adult-onset Still's disease (AOSD) and to predict disease phenotypes. In total, 49 patients diagnosed with AOSD and 200 patients with common diseases (controls) were included in the analysis. The levels of 69 cytokines were analyzed using a multi-suspension cytokine array. Cytokine cluster analysis was performed to identify specific molecular networks. Furthermore, random forest analysis and logistic regression analysis were used to rank cytokines based on their importance and to determine specific biomarkers for identification of AOSD patients and phenotypes. Patients with AOSD demonstrated significantly higher macrophage migration inhibitory factor (MIF) and interleukin (IL)-12(p40) serum levels than controls and patients with rheumatoid arthritis. Serum levels of chemokine (C-C motif) ligand (CCL) 8 and CCL22 were significantly lower in AOSD patients with a polycyclic systemic disease phenotype and could be differentiated with high accuracy from the other phenotypes (cutoff value for CCL8 = 122.7 pg/mL, CCL22 = 593.3 pg/mL, sensitivity 66.7%, specificity 87.1%, area under the curve 0.843). Combined MIF and IL-12(p40) levels may represent a biomarker for differentiating patients with AOSD from those with other diseases. The chemokine profiles of AOSD with a polycyclic systemic disease phenotype may differ from other phenotypes.

Adult-onset Still's disease masquerading as acute coronary syndrome: a case report and review of the literature.

INTRODUCTION: Adult-onset Still's disease is a rare systemic autoinflammatory disease. We present a case of a young man with a constellation of symptoms and myopericarditis as a complication of this disease. CASE: A 36-year-old Hispanic man with no significant past medical history developed a quotidian fever pattern following an upper respiratory tract infection. He initially presented with chest pain concerning for myocardial infarction and underwent cardiac catheterization, which revealed non-obstructive coronary artery disease. He was found to have myopericarditis, significant neutrophilic leukocytosis, and hyperferritinemia. He improved on high-dose corticosteroids but developed steroid-induced psychosis, and 4 months from symptom onset, he finally received tocilizumab, which eventually induced remission without adverse reactions. DISCUSSION: Adult-onset Still's disease should be considered in a patient with fevers of undetermined origin. Due to its multisystemic involvement, adult-onset Still's disease is often a diagnosis arrived at after an extensive cardiac, hematologic, malignant, and infectious workup. Imaging, laboratory testing, and bone marrow biopsy were necessary to rule out alternative etiologies of this patient's presentation. Steroids are the mainstay of treatment because they are easily affordable, although the high risk of adverse effects makes them less desirable. Interleukin-1 inhibitors (anakinra or canakinumab) and interleukin-6 inhibitor tocilizumab are the steroid-sparing biologic agents of choice but are cost-prohibitive. CONCLUSION: Adult-onset Still's disease should be considered in the differential diagnoses of fever of undetermined origin. Early identification and initiation of treatment are critical to faster recovery and prevention of progression to severe complications. Steroids remain the standard first-line therapy and should be followed by disease-modifying steroid sparing drugs. The social determinants of health may preclude their timely initiation and should alert providers of proactive ways to avoid further delays.

The role of 18FDG-PET imaging in VEXAS syndrome: a multicentric case series and a systematic review of the literature.

VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, and somatic) syndrome is characterized by heterogeneous clinical manifestations. Due to the inflammatory nature of this condition, 18-FDG-PET (18-fluorodeoxyglucose-positron emission tomography) might be used to diagnose and monitor the disease. However, no data are available about the most common findings of PET imaging in this disease. For this reason, we summarised all the available reports of patients with VEXAS who underwent at least one PET scan and described 8 additional patients' PET from our centres. Overall, we described 35 patients' PET findings. All patients were male, with a median age of 70 years. The most frequent hypermetabolic sites on PET scans were the bone marrow (77.1%), lymph nodes (35.3%), lungs (28.6%), spleen and large vessels (22.9%), and cartilage (20%). Six patients underwent a PET scan 2.7 ± 1.5 years before VEXAS diagnosis, showing nonspecific uptake in the bone marrow. Four patients had a follow-up PET scan, showing a decrease or a disappearance of the previously identified hypermetabolic areas. In conclusion, although no specific uptake site has been found for VEXAS syndrome, PET imaging could help detect inflammatory foci that are not clinically evident. In addition, high metabolic activity in bone marrow might precede the clinical onset of the disease, shedding light on the pathogenesis of VEXAS.

Anakinra in the management of adult-onset still's disease: a single-center experience.

Adult-onset Still's disease (AOSD) is a rare systemic autoinflammatory disorder of unknown etiology characterized by systemic inflammation, high fever, salmon-colored skin rash, arthralgia, and arthritis. Patients with AOSD may also present with elevated inflammatory markers, hyperferritinemia, anemia, leukocytosis, hepatosplenomegaly, and lymphadenopathy. Glucocorticoids and biological disease-modifying anti-rheumatic drugs, including the anti-interleukin-1 agent anakinra, are used in the management of AOSD. This retrospective single-center study included patients with AOSD who were registered at our tertiary center, and received anakinra treatment. The primary outcome of our study was the proportion of patients who achieved complete remission of disease-related clinical and laboratory complications. The glucocorticoid treatment profiles of the included patients before and after anakinra treatment were also analyzed. The occurrence of serious and non-serious adverse events was recorded to analyze the safety profile of anakinra. Thirty-four patients with AOSD, including 25 females (73.5%), were enrolled in the study. Twelve patients (35.3%) achieved complete remission and 14 patients (41.2%) achieved partial remission after anakinra treatment. Eight patients (23.5%) did not response to anakinra. Anakinra significantly decreased the number of patients receiving glucocorticoid treatment [33 (97%) vs. 22 (64.7%), p < 0.001] and the mean daily glucocorticoid dose [19 ± 13.5 mg vs. 4.6 ± 5.8 mg, p < 0.001]. Mild adverse events occurred in 11 patients (32.3%) with injection site reactions being the most common. One patient (2.9%) was diagnosed with tuberculosis within the treatment period. Anakinra is an effective and generally safe option for biological treatment initiation in the management of AOSD.

Adult-Onset Still's Disease (AOSD)-On the Basis of Own Cases.

INTRODUCTION: Adult-onset Still's disease (AOSD) is a rare chronic autoinflammatory condition characterized by a spiking fever, arthritis, a rash, hepatosplenomegaly, lymphadenopathy, leucocytosis, and hyperferritinemia. It is sometimes accompanied by life-threatening complications like macrophage activation syndrome/hemophagocytic lymphohistiocytosis (MAS/HLH). Treatment options for AOSD include glucocorticoids (GCs), immunosuppressive drugs, biological medications, and Janus kinase (JAK) inhibitors. The features that differentiate MAS/HLH from AOSD are: in MAS/HLH, a different type of fever, which is persistent, a sharp decrease in the number of leukocytes and thrombocytes, a further increase in the level of transaminases and ferritin, significant hepatosplenomegaly, lymphadenopathy, symptoms of the central nervous system (CNS), disseminated intravascular coagulation (DIC) and hemophagocytosis in the bone marrow. This study aimed to evaluate the course of AOSD, which results in MAS/HLD. PATIENTS AND METHODS: Nine AOSD patients, four of whom developed MAS/HLH, were treated at the Rheumatology Clinic in the Central Clinical Hospital of the Ministry of Interior Affairs from 1 January 2015 to 15 March 2020 and at the Rheumatology Clinic in the National Institute of Geriatric, Rheumatology and Rehabilitation from 1 September 2021 to 1 March 2024. Medical history, clinical data, demographic data, laboratory data, imaging data, Hscore, and treatment data were collected. RESULTS: All the patients with MAS and an Hscore above 150 recovered. DISCUSSION: MAS/HLH requires rapid diagnosis as well as treatment with methylprednisolone pulses, cyclosporine A, and etoposide. When comparing patients who developed MAS/HLH with those who did not, possible risk factors were identified: the presence of pregnancy (two cases) and an aggressive course of AOSD. The Hscore is a useful tool for identifying patients with MAS/HLH.

Systemic auto-inflammatory manifestations in patients with spondyloarthritis.

OBJECTIVES: (1) characterizing a group of spondyloarthritis (SpA) patients with systemic auto-inflammatory symptoms (S-SpA); (2) comparing SpA features with and without auto-inflammatory symptoms; (3) comparing the auto-inflammatory features of S-SpA and Still's disease (SD). METHODS: Retrospective observational study. Clinical data of adult and pediatric patients with S-SpA, SD or SpA were collected retrospectively and analyzed. RESULTS: Forty-one subjects with S-SpA, 39 with SD and 42 with SpA were enrolled. The median latency between systemic and articular manifestations in S-SpA was 4.4 (IQR: 7.2) years. S-SpA and SpA had similar frequency of peripheral arthritis and enthesitis (N.S.), while tenosynovitis was more frequent (P=0.01) and uveitis less frequent (P<0.01) in S-SpA. MRI showed signs of sacroiliac inflammation and damage in both S-SpA and SpA equally (N.S.). S-SpA patients had less corner inflammatory lesions (P<0.05) and inflammation at the facet joints (P<0.01), more interspinous enthesitis (P=0.01) and inter-apophyseal capsulitis (P<0.01). Compared to SD, S-SpA patients had lower-grade fever (P<0.01), less rash (P<0.01) and weight loss (P<0.05), but more pharyngitis (P<0.01), gastrointestinal symptoms (P<0.01) and chest pain (P<0.05). ESR, CRP, WBC, ANC, LDH tested higher in SD (P<0.01). Resolution of systemic symptoms was less frequent in S-SpA than SD on corticosteroid (P<0.01) and methotrexate (P<0.05) treatment. When considering all SD patients, a complete response to corticosteroids in the systemic phase significantly reduced the likelihood of developing SpA (OR=0.06, coefficient -2.87 [CI: -5.0 to -0.8]). CONCLUSIONS: SpA should be actively investigated in patients with auto-inflammatory manifestations, including undifferentiated auto-inflammatory disease and SD.

Musculoskeletal ultrasound findings in adult-onset Still's disease: A case series.

Adult-onset Still's disease (AOSD) is a rare systemic inflammatory disorder of unknown etiology characterized by high spiking fever, salmon-like skin rash, arthritis, and elevated serum ferritin levels. Early detection of AOSD is remarkably difficult because of the lack of serologic biomarkers, nonspecific presentation, and rarity of the disease. Although arthralgia and arthritis are the most frequent symptoms and are correlated with health-related quality of life in patients with AOSD, the inflammatory changes associated with these symptoms have not been elucidated. We performed musculoskeletal ultrasound (MSKUS) in 11 patients between January 1, 2008 and July 31, 2023, seven of whom had abnormalities. MSKUS findings of those cases suggested that some patients with AOSD could present with tenosynovitis, tendonitis/peritendonitis, bursitis, and enthesitis along with synovitis. This case series demonstrate the diversity of inflammatory articular manifestations of AOSD identified by MSKUS.

Beyond the Norm: A Unique Case of Adult-Onset Still's Disease.

Polyserositis, characterized by inflammation of multiple serous membranes, frequently occurs secondary to infection, malignancy, or rheumatological disorders. Adult-onset Still's disease (AOSD) is often diagnosed by exclusion, with the Yamaguchi criteria being essential for diagnosis. Disease severity is likely due to immune system changes, comorbidities, delayed diagnosis, and a higher risk of complications, necessitating more aggressive and carefully monitored treatments. We report the case of an elderly male who was diagnosed with AOSD by exclusion using the Yamaguchi criteria. The patient presented with bilateral pleural effusion, systemic inflammation, arthralgia, and fever. Initial investigations included complete blood count, C-reactive protein, and erythrocyte sedimentation rate, which revealed a severe acute phase reactant. Imaging studies, including chest X-ray and CT scan, revealed bilateral pleural effusion. Despite traditional treatment approaches, such as high doses of steroids and other immunosuppression medications, the patient's condition remained refractory, indicating the complex and challenging nature of managing AOSD in elderly patients. The increased severity and higher complication rates in older individuals require a multidisciplinary approach to ensure optimal outcomes. Aggressive treatment strategies, vigilant monitoring, and thorough diagnostic workups are essential to manage the disease effectively. This case highlights the need for heightened awareness and consideration of elderly onset Still's disease (EOSD) in differential diagnoses for elderly patients presenting with polyserositis and systemic inflammatory symptoms.

Similarities and differences between systemic juvenile idiopathic arthritis and adult-onset Still's disease: a multicenter Spanish study.

To describe the characteristics of systemic juvenile idiopathic arthritis (sJIA) and adult-onset Still's disease (AOSD), compare their presentation and evolution, and analyse possible complication predictors. Multicenter study. Data were retrieved from a hospital-based study of patients with a diagnosis or suspected diagnosis of sJIA or AOSD according to the responsible physician and followed-up for at least one year. Descriptive variables (classification criteria, clinical manifestations, complications, family, and personal history) were collected at disease onset and during follow-up. We present the clinical characteristics of 326 patients, 67% of whom had a diagnosis of sJIA and 33% of AOSD. Clinical manifestation frequencies were similar between the two groups, except for odynophagia, which was significantly more frequent in AOSD than in sJIA (78.4% vs. 25.5%; p < 0.0001). Among the complications, macrophage activation syndrome (MAS) was significantly more common in sJIA than in AOSD (24.4% vs. 9.5%; p = 0.002), to the extent that an sJIA diagnosis significantly increased the risk of MAS, together with serositis presence, and the need for biological therapy. Patients with sJIA and AOSD showed similar characteristics, supporting the idea that they are both part of Still's disease, but are expressed at different ages. Differences in manifestations and complications might be due to different management between diseases and immune response maturity.

Indices and ferritin level that predict organ involvement in adult-onset Still's disease.

Aim: The aim of the study is to evaluate whether C-reactive protein to albumin ratio (CAR), lactate dehydrogenase to albumin ratio (LAR), ferritin to erythrocyte sedimentation rate ratio (FER), systemic immune-inflammation index (SII), prognostic nutritional index (PNI) indices and ferritin level can predict organ involvement in adult-onset Still's disease (AOSD) patients.Methods: This study was planned as a cross-sectional study. Univariate and multivariate logistic regression analyses were performed to evaluate the usefulness of ferritin level and inflammatory indices in defining organ involvement.Results: Sixty-one patients diagnosed with AOSD were included in this study. Multivariate logistic regression analyzes showed that LAR (OR 1.028, 95% CI: 1.011-1.044) (p = 0.001) index predicted lymphadenopathy involvement, CAR (OR 1.249, 95% CI: 1.087-1.435) (p = 0.002) index predicted hepatomegaly involvement, ferritin level (OR 1.004, 95% CI: 1.001-1.008) (p = 0.007) predicted splenomegaly involvement, FER (OR 1.085, 95% CI: 1.012-1.164) (p = 0.021) and PNI (OR 0.271, 95% CI: 1.132-0.553) (p < 0.001) index predicted the occurrence of serositis.Conclusion: This study showed that ferritin level, CAR, FER, PNI and LAR markers may predict organ involvement at diagnosis in AOSD patients.

[Box: see text].

Adult-Onset Still's Disease: An Atypical Presentation Refractory to Standard Treatment.

A previously healthy young female of Southeast Asian descent presented with a two-week history of polyarthritis, urticarial rash, sore throat, and 8.6 kg of unintentional weight loss. The initial workup revealed a positive parvovirus B19 polymerase chain reaction with hyperferritinemia. The patient was diagnosed with adult-onset Still's disease (AOSD) secondary to parvovirus B19 infection. Bone marrow biopsy also showed evidence of hemophagocytic lymphohistiocytosis. Viral and bacterial infections may trigger AOSD in genetically susceptible hosts either via an unknown mechanism or by direct cytotoxic effect. This case shows an atypical presentation of AOSD, as well as the challenge in diagnosing and treating AOSD complicated by macrophage activation syndrome refractory to standard treatment.

Cracking the code: high ferritin load with Salmon-Colored skin episodes.

A 37-year-old previously healthy male presented to the Emergency Department with a two-week history of intermittent fevers, joint pain, sore throat, and a diffuse salmon-colored rash. Examination revealed a pruritic rash with joint swelling and red spots in the oropharynx. Initial sepsis management was instituted, but subsequent investigations, including infectious, hematologic, and autoimmune workups, were inconclusive. Notably, elevated ferritin levels prompted consideration of life-threatening conditions like Hemophagocytic Lymphohistiocytosis, which was ultimately ruled out. Adult-onset Still's Disease (AOSD) emerged as the leading diagnosis following the exclusion of other potential causes. A skin biopsy was performed with non-specific findings and corticosteroid treatment led to significant improvement. This case illustrates the clinical decision-making process of diagnosing AOSD and highlights the potential utility of novel AI technology in dermatologic assessments.

Successful maintenance therapy with tocilizumab for severe acute liver failure associated with adult-onset still's disease.

Elevated liver enzymes are commonly observed among adult-onset Still's disease (AOSD), but severe acute liver failure is extremely rare. Although severe acute liver failure associated with AOSD poses a life-threatening condition, the appropriate treatment is unclear. Some case reports have demonstrated the efficacy of high-dose prednisolone (PSL) and cyclosporin A (CyA), although the adverse effects of CyA led certain patients to cease its use. Therefore, an alternative treatment option is crucial, and thus far, there have been no reports of tocilizumab (TCZ) being used for this severe phenotype. Here, we report the first case of successful treatment using TCZ as maintenance therapy for severe ALF associated with AOSD. Following initial treatment with high-dose PSL and CyA, our case was switched to TCZ due to CyA-related side effects including alopecia and tremors. Our case highlights TCZ as a potential option for maintenance therapy of this severe condition.

The History of Macrophage Activation Syndrome in Autoimmune Diseases.

In 1979, it became recognized in the literature that what we call hemophagocytic lymphohistiocytosis (HLH) was a nonmalignant disease of histiocytes. Subsequently a familial form and a secondary form of HLH were differentiated. When HLH is secondary to an autoimmune disease, rheumatologists refer to this entity as macrophage activation syndrome (MAS) to differentiate it from HLH itself. Although the first cases of MAS likely appeared in the literature in the 1970s, it was not until 1985 that the term activated macrophages was used to describe patients with systemic juvenile idiopathic arthritis (sJIA) complicated by MAS and the term macrophage activation syndrome first appeared in the title of a paper in 1993.MAS is one of the many types of secondary HLH and should not be confused with primary HLH. Experience has taught that MAS secondary to different autoimmune diseases is not equal. In the 30 years since initial description in patients with sJIA, the clinical spectrum, diseases associated with MAS, therapy, and understanding the pathogenesis have all made significant gains. The diagnostic/classification criteria for MAS secondary to sJIA, SLE, RA, and KD differ based on the different laboratory abnormalities associated with each (Ahn et al., J Rheumatol 44:996-1003, 2017; Han et al., Ann Rheum Dis 75:e44, 2016; Ravelli et al., Ann Rheum Dis 75:481-489, 2016; Borgia et al., Arthritis Rheumatol 70:616-624, 2018). These examples include the thrombocytosis associated with sJIA, a chronic generalized activation of the immune system, leading to elevations of fibrinogen and sIL-2R, low platelet count associated with SLE, and more acute inflammation associated with KD. Therefore, individual diagnostic criteria are required, and they all differ from the diagnostic criteria for HLH, which are based on a previously non-activated immune system (Ahn et al., J Rheumatol 44:996-1003, 2017; Han et al., Ann Rheum Dis 75:e44, 2016; Ravelli et al., Ann Rheum Dis 75:481-489, 2016; Borgia et al., Arthritis Rheumatol 70:616-624, 2018; Henter et al., Pediatr Blood Cancer 48:124-131, 2007). This helps to explain why the HLH diagnostic criteria do not perform well in MAS.The initial treatment remains high-dose steroids and IVIG followed by the use of a calcineurin inhibitor for resistant cases. IVIG can be used if there is a concern about malignancy to wait for appropriate investigations or with steroids. Interluekin-1 inhibition is now the next therapy if there is a failure to respond to steroids and calcineurin inhibitors. Advances in understanding the mechanisms leading to MAS, which has been greatly aided by the use of mouse models of MAS and advances in genome sequencing, offer a bright future for more specific therapies. More recent therapies are directed to specific cytokines involved in the pathogenesis of MAS and can lead to decreases in the morbidity and mortality associated with MAS. These include therapies directed to inhibiting the JAK/STAT pathway and/or specific cytokines, interleukin-18 and gamma interferon, which are currently being studied in MAS. These more specific therapies may obviate the need for nonspecific immunosuppressive therapies including high-dose prolonged steroids, calcineurin inhibitors, and etoposide.

Criteria for Cytokine Storm Syndromes.

In the past two decades, there has been a great deal of work aimed to devise diagnostic guidelines, classification criteria, and diagnostic scores for cytokine storm syndromes (CSSs). The most notable effort has been the large-scale multinational study that led to the development of the 2016 classification criteria for macrophage activation syndrome (MAS) complicating systemic juvenile idiopathic arthritis (JIA). Future studies should scrutinize the validity of the proposed criteria, particularly in systemic JIA patients treated with biologics, in children with subtle or incomplete forms of MAS, and in patients with MAS complicating other rheumatologic disorders. More generic CSS criteria are also available but often lack sensitivity and specificity in a wide variety of patient populations and CSSs of different etiologies. The coronavirus disease 2019 (COVID-19)-related lung disease led to an evolution of the concept of a "cytokine storm." Emerging and unsolved challenges in the diagnosis of the different forms of CSSs highlight the need for diagnostic tools and well-established classification criteria to enable timely recognition and correct classification of patients.

Macrophage Activation Syndrome in the Setting of Rheumatic Diseases.

Patients with established rheumatic disorders may develop complications of macrophage activation syndrome due to severe flares of the underlying disease (adult-onset Still's disease, SLE); however, in most other rheumatic disorders, MAS develops in association with identified viral or other infectious triggers. It is therefore important to pursue appropriate studies to identify potential infectious triggers in rheumatic disease patients who develop MAS. Management is best directed toward treatment of the triggering infections and combinations of high-dose corticosteroids, calcineurin inhibitors, and biologic therapies targeting IL-1 and/or IL-6 to suppress the associated cytokine storm.

Risk factors for adverse drug reactions to sulfamethoxazole-trimethoprim prophylaxis in patients with rheumatic and musculoskeletal diseases.

OBJECTIVES: Risk factors for adverse drug reactions (ADRs) associated with prophylactic sulfamethoxazole-trimethoprim (SMX/TMP) in patients with rheumatic and musculoskeletal diseases undergoing immunosuppressive therapy remain unclear, we aimed to identify the risk factors associated with ADRs. METHODS: Consecutive patients with rheumatic and musculoskeletal diseases, who were admitted to Keio University Hospital and received prophylactic administration of SMX/TMP, were included. Data regarding ADRs to SMX/TMP were collected to identify associated risk factors using multivariable analysis. RESULTS: Of 438 patients included in the analysis, 82 (18.7%) experienced ADRs. Patients in the ADRs group were significantly older, had chronic kidney disease, and exhibited lower lymphocyte and platelet counts, lower albumin levels, lower estimated glomerular filtration rates, higher aspartate aminotransferase levels, and higher ferritin levels than those in the non-ADR group. Regarding underlying rheumatic and musculoskeletal diseases, adult-onset Still's disease (ASD) was associated with a significantly higher incidence of ADRs (67%) than other diseases. Multivariable analysis identified the presence of ASD and low lymphocyte counts as independent risk factors for allergic ADRs, and older age and use of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers for non-allergic ADRs. CONCLUSIONS: Risk factors for ADRs associated with prophylactic SMX/TMP treatment in patients with rheumatic and musculoskeletal diseases were identified.