Sulfasalazine-induced drug reaction with eosinophilia and systemic symptoms (DRESS) coinfected with COVID-19 complicated by hemophagocytic lymphohistiocytosis: a case report.

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) is characterized by a widespread maculopapular rash, lymphadenopathy, fever, and multisystem involvement. Conversely, hemophagocytic lymphohistiocytosis (HLH) is an infrequent yet critical condition presenting with fever, hepatosplenomegaly, cytopenias, coagulation abnormalities, and elevated inflammatory markers. The overlapping clinical and laboratory features between DRESS and HLH poses a significant diagnostic challenge. Secondary HLH (sHLH) typically occurs in adults triggered by viral infections, malignancies, rheumatologic diseases, or immune deficiencies. Recently, COVID-19 has also been identified as one of the triggers for sHLH. Herein, we present a case of Sulfasalazine-induced DRESS coinfected with COVID-19 that subsequently progressed into HLH. Our patient exhibited common hepatorenal and splenic involvement along with rare cholecystitis and appendicitis. However, a significant improvement was observed upon the addition of etoposide and azathioprine. We hypothesize that excessive activation of the immune system and cytokine storm due to DRESS combined with COVID-19 infection led to more extensive systemic damage resulting in HLH development. This highlights the potential for severe consequences when DRESS coincides with HLH during a COVID-19 infection.

Risk-stratified monitoring for sulfasalazine toxicity: prognostic model development and validation.

BACKGROUND: Sulfasalazine-induced cytopenia, nephrotoxicity and hepatotoxicity is uncommon during long-term treatment. Some guidelines recommend 3 monthly monitoring blood tests indefinitely during long-term treatment while others recommend stopping monitoring after 1 year. To rationalise monitoring, we developed and validated a prognostic model for clinically significant blood, liver or kidney toxicity during established sulfasalazine treatment. DESIGN: Retrospective cohort study. SETTING: UK primary care. Data from Clinical Practice Research Datalink Gold and Aurum formed independent development and validation cohorts. PARTICIPANTS: Age ≥18 years, new diagnosis of an inflammatory condition and sulfasalazine prescription. STUDY PERIOD: 1 January 2007 to 31 December 2019. OUTCOME: Sulfasalazine discontinuation with abnormal monitoring blood-test result. ANALYSIS: Patients were followed up from 6 months after first primary care prescription to the earliest of outcome, drug discontinuation, death, 5 years or 31 December 2019. Penalised Cox regression was performed to develop the risk equation. Multiple imputation handled missing predictor data. Model performance was assessed in terms of calibration and discrimination. RESULTS: 8936 participants were included in the development cohort (473 events, 23 299 person-years) and 5203 participants were included in the validation cohort (280 events, 12 867 person-years). Nine candidate predictors were included. The optimism adjusted R2 D and Royston D statistic in the development data were 0.13 and 0.79, respectively. The calibration slope (95% CI) and Royston D statistic (95% CI) in validation cohort was 1.19 (0.96 to 1.43) and 0.87 (0.67 to 1.07), respectively. CONCLUSION: This prognostic model for sulfasalazine toxicity uses readily available data and should be used to risk-stratify blood-test monitoring during established sulfasalazine treatment.

Labetalol Ameliorates Experimental Colitis in Rat Possibly Through its Effect on Proinflammatory Mediators and Oxidative Stress.

BACKGROUND: Members of beta blockers drugs possess significant antioxidant activities. The current research is to assess the effect of the labetalol on acetic acid (AA-induced) colitis in rat model. METHODS: Forty adult Wistar rats were separated into 4 groups, including the negative control group, AA group, AA + sulfasalazine (100 mg/kg/day) group, and AA + labetalol (300 mg/kg/day) group. Colitis was induced in rats by the interrectal installation of 2 mL of 4% (v/v) AA. Sulfasalazine and labetalol were administered orally for 7 days after 2 hours of induction. The following parameters were measured: disease activity index (DAI), histopa-thological changes and colon tissue homogenate concentrations of proinflammatory mediators IL-1ß, adhesion molecules ICAM-1, and oxidative stress marker myeloperoxidase (MPO). RESULTS: The treatment with labetalol significantly reduced DAI and histopathological changes induced by AA. Also, labetalol markedly decreased the concentrations of IL-1ß, ICAM-1, and MPO in colonic tissue that were increased by AA. The effects of labetalol were significantly lower than that produced by sulfasalazine as standard drug. CONCLUSIONS: Labetalol exerts ameliorative effects on disease activity and histopathological features of AA-induced colitis in rats possibly through antioxidant effects and inhibition of inflammatory mediators.

Sulfasalazine ameliorates lipopolysaccharide-induced acute lung injury by inhibiting oxidative stress and nuclear factor-kappaB pathways.

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) has a high mortality rate and incidence of complications. The pathophysiology of ALI/ARDS is still not fully understood. The lipopolysaccharide (LPS)-induced mouse model of ALI has been widely used to study human ALI/ARDS. Sulfasalazine (SASP) has antibacterial and anti-inflammatory effects and is used for treating inflammatory bowel and rheumatic diseases. However, the effect of SASP on LPS-induced ALI in mice has not yet been reported. Therefore, we aimed to investigate the effect of SASP on LPS-induced ALI in mice. Mice were intraperitoneally injected with SASP 2 h before or 4 h after LPS modeling. Pulmonary pathological damage was measured based on inflammatory factor expression (malondialdehyde and superoxide dismutase levels) in the lung tissue homogenate and alveolar lavage fluid. The production of inflammatory cytokines and occurrence of oxidative stress in the lungs induced by LPS were significantly mitigated after the prophylactic and long-term therapeutic administration of SASP, which ameliorated ALI caused by LPS. SASP reduced both the production of inflammatory cytokines and occurrence of oxidative stress in RAW264.7 cells, which respond to LPS. Moreover, its mechanism contributed to the suppression of NF-κB and nuclear translocation. In summary, SASP treatment ameliorates LPS-induced ALI by mediating anti-inflammatory and antioxidant effects, which may be attributed to the inhibition of NF-κB activation and promotion of antioxidant defenses. Thus, SASP may be a promising pharmacologic agent for ALI therapy.

Qingchang suppositry induced remission in patients with mild-to-moderate ulcerative proctitis: a multicenter, prospective, randomized, parallel-controlled clinical trial.

OBJECTIVE: To evaluate the efficacy and safety of Qingchang suppository (, QCS), a preparation of Chinese herbal medicine, in the induction of remission in patients with mild-to-moderate ulcerative proctitis (UP). METHODS: We performed a multicenter, prospective, randomized, parallel-controlled trial to evaluate the efficacy of QCS induction therapy in 140 adult patients with mild-to-moderate UP and TCM syndrome of dampness-heat in large intestine. The patients were randomized to receive QCS (study group) or Salicylazosulfapyridine (SASP) suppository (control group) one piece each time, twice a day, per anum for 12 weeks. Mayo score and main symptoms score were evaluated at weeks 0, 2, 4, 8 and 12, rectosigmoidscopy was taken at weeks 0, 4, 8 and 12, Geboes score, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and safety indexes were assessed at weeks 0 and 12. The primary efficacy endpoint is clinical remission rate, the secondary efficacy endpoints are clinical response rate, mucosa healing rate, Geboes score, the remission rates of the main symptoms, the median day to the remission of the symptom, etc. RESULTS: There were no statistical difference in the clinical remission rates, the clinical response rates, the mucosa healing rates, Geboes score, ESR and CRP between the two groups. The remission rates of tenesmus and anal burning sensation of the study group were significantly higher than those of the control group (76.5% vs 25.0%, P = 0.009; 74.51% vs 29.63%, P = 0.003). The median day to the remission of purulent bloody stool of the study group was significantly less than that of control group [11 (1, 64) vs 19 (2, 67), P = 0.007]. The patients receiving QCS had a significantly higher mucosa healing rate at week 4 than the patients receiving SASP suppository (71.42% vs 52.85%, P = 0.023). No adverse event occurred in the study group while the adverse events incidence of the control group was 5.7% (P = 0.049). CONCLUSIONS: QCS could induce the remission of UP as effectively and safely as SASP suppository, and was superior to SASP suppository in relieving the symptoms of tenesmus, anal burning sensation and purulent bloody stool and the time to reach mucosa healing.

Sulfasalazine-Induced Delayed Hypersensitivity Reaction Presenting as Fever, Aseptic Meningitis, and Mesenteric Panniculitis in a Patient with Seronegative Arthritis.

BACKGROUND An 82-year-old woman presented with acute pyrexial illness and mesenteric panniculitis and developed biochemical aseptic meningitis (cerebrospinal fluid pleocytosis with no identifiable pathogen). Investigation determined her illness was likely a delayed hypersensitivity reaction caused by sulfasalazine. Sulfasalazine-induced aseptic meningitis is a rare condition often diagnosed late in a patient's admission owing to initial non-specific illness symptomatology requiring the exclusion of more common "red flag" etiologies, such as infection and malignancy. CASE REPORT An 82-year-old woman with a history of recurrent urinary tract infections and seronegative arthritis presented with a 3-day history of fatigue, headache, dyspnea, and lassitude. On admission, she was treated as presumed sepsis of uncertain source owing to pyrexia and tachycardia. Brain computer tomography (CT) revealed no acute intracranial abnormality. Furthermore, CT of the chest, abdomen, and pelvis did not reveal any source of sepsis or features of malignancy. After excluding infective etiologies with serological and cerebrospinal fluid testing, sulfasalazine-induced aseptic meningitis (SIAM) was diagnosed. The patient was then commenced on intravenous steroids, resulting in immediate defervescence and symptom resolution. CONCLUSIONS SIAM remains a diagnostic challenge since patients present with non-specific signs and symptoms, such as pyrexia, headaches, and lassitude. These patients require a thorough investigative battery starting with anamnesis, physical examination, biochemical testing, and radiologic imaging. This case illustrates the need for a high suspicion index of drug-induced hypersensitivity reaction in a rheumatological patient with pyrexial illness where infective etiologies have been confidently excluded. Prompt initiation of intravenous steroids in SIAM provides a dramatic recovery and resolution of symptoms.

[A case of ulcerative colitis with mesalazine intolerance complicated with agranulocytosis and septic shock during salazosulfapyridine administration].

A 73-year-old woman developed ulcerative colitis with mesalazine intolerance a year ago. She relapsed 10 months later. Although she was in clinical remission with salazosulfapyridine (SASP) and prednisolone administration, she developed agranulocytosis 53 days following SASP administration. She went into septic shock;however, she recovered with antibiotics, granulocyte colony-stimulating factor, and cardiotonic agents. Drug-induced lymphocyte stimulation test was positive for both mesalazine and SASP. Drug selection should be carefully determined in patients with 5-aminosalicylic acid intolerance.

[Stevens-Johnson syndrome in a patient with positive lymphocyte transformation test]. / Síndrome de Stevens-Johnson en una paciente con prueba positiva de transformación linfocitaria.

BACKGROUND: Stevens-Johnson syndrome is a severe drug reaction. Sulfonamides have been associated with drug reactions, complications, sequelae, even death. CASE REPORT: A 40-year-old female patient with a medical history of endometriosis and recently diagnosed chronic inflammatory ulcerative colitis. She was treated at the Allergology service of the San Juan de Dios Hospital of the Costa Rican Social Security Fund, and after 20 days of treatment with sulfasalazine she had a severe drug reaction on the skin, compatible with Stevens-Johnson syndrome. The lymphocyte transformation test was positive, confirming sulfasalazine as the causative agent. CONCLUSION: The lymphocyte transformation test is a useful method that can confirm the causative agent and prevent important complications in the future.

ANTECEDENTES: El síndrome de Stevens-Johnson es una reacción medicamentosa severa. Las sulfamidas se han asociado con reacciones medicamentosas, complicaciones, secuelas, incluso la muerte. REPORTE DE CASO: Paciente femenina de 40 años, con antecedentes médicos de endometriosis y colitis ulcerativa crónica inflamatoria de reciente diagnóstico. Fue atendida en el servicio de Alergología del Hospital San Juan de Dios de la Caja Costarricense del Seguro Social, y luego de 20 días de tratamiento con sulfasalazina tuvo una reacción medicamentosa severa en la piel, compatible con síndrome de Stevens-Johnson. La prueba de transformación linfocitaria resultó positiva, con lo que se confirmó la sulfasalazina como el agente causal. CONCLUSIÓN: La prueba de transformación linfocitaria es un método útil que puede confirmar el agente causal y prevenir complicaciones importantes a futuro.

Laryngeal edema in drug reaction with eosinophilia and systemic symptoms syndrome due to sulfasalazine.

We present a case of a 47-year-old man with drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome. The patient had been diagnosed with rheumatoid arthritis and sulfasalazine was prescribed 4 weeks before admission. Initial symptoms with fever and rash worsened even after a discontinuation of the medication, and concomitant symptoms developed including typical manifestations of facial rash and edema sparing the periorbital area, as well as atypical laryngeal edema. Rheumatologists should be aware that sulfasalazine is derived from sulfonamide and can possibly induce DRESS syndrome, one of the life-threatening drug eruptions.

Effects of sulfasalazine in axial spondyloarthritis on COVID-19 outcomes: real-life data from a single center.

INTRODUCTION: Compared to biological agents, little is known about the impact of sulfasalazine therapy on COVID-19 outcomes in patients with Axial Spondyloarthritis (AxSpA). Therefore, we aimed to evaluate the COVID-19 severity in AxSpAs receiving sulfasalazine and biologic-agent. MATERIALS AND METHODS: A total of 219 SARS-CoV-2 positive AxSpA patients were retrospectively analyzed. COVID-19 pneumonia, hospitalization rate, and length of stay were used to determine COVID-19 severity. AxSpA patients were mainly grouped and compared as sulfasalazine and non-sulfasalazine. Afterward, we excluded no-treatment patients to reveal the drug's effects more clearly and regrouped AxSpA patients as sulfasalazine-monotherapy (34.3%), biologic-monotherapy (33.7%), and sulfasalazine + biologic (7.3%). RESULTS: Fifty-nine percent of the patients were male and the mean age was 45.0 years. Peripheral arthritis was 35% and uveitis 15%. In total, 41.5% of them have received sulfasalazine and 41.0% biologic agents, and the remaining patients with no AxSpA-specific treatment. In the first comparison, the sulfasalazine group had a higher age, more frequent COVID-19 pneumonia, hospitalization, and longer hospitalization than a non-sulfasalazine group. In the pairwise comparison of 3 treatment groups, the demographic and clinical features, the hospitalization rate and the length of hospital stay were similar but the sulfasalazine-monotherapy group had a higher frequency of COVID-19 pneumonia than the biologic-monotherapy group (23% vs. 7%, p = 0.008). CONCLUSION: Our results imply sulfasalazine may be related to more severe COVID-19 in AxSpA patients. These patients should be followed more carefully in the presence of COVID-19, regardless of reasons such as age, comorbidity, and extra-axial disease, and consideration of discontinuing sulfasalazine maybe even thought.

Development of Inflammatory Bowel Disease in Children With Juvenile Idiopathic Arthritis Treated With Biologics.

OBJECTIVE: The aim of our study was to describe the distinct features of inflammatory bowel disease (IBD) in juvenile idiopathic arthritis (JIA) patients and to identify risk factors for its development. METHODS: Data from the German biologics in pediatric rheumatology registry (Biologika in der Kinderrheumatologie) collected between 2001 and 2021 were analyzed retrospectively. RESULTS: In 5009 JIA patients, 28 developed confirmed IBD before the age of 18 years: 23 (82.1%) with Crohn disease (CD), 4 (14.3%) with ulcerative colitis (UC), and 1 (3.6%) with IBD-unclassified (IBD-U). The incident rate of IBD during 20 years of observation was 0.56% (0.46% for CD, 0.08% for UC, and 0.02% for IBD-U), of whom 20.3% were HLA-B27 positive, 25% had enthesitis-related arthritis, and 14.3% psoriatic arthritis. Within 90 days before IBD diagnosis, 82.1% (n = 23) received treatment with etanercept (ETA), 39.3% (n = 11) non-steroidal anti-inflammatory drugs, 17.9% (n = 5) systemic corticosteroids, 8 (28.6%) methotrexate (MTX), 14.3% (n = 4) sulfasalazine, 10.7% (n = 3) leflunomide, and 3.6% (n = 1) adalimumab and infliximab, respectively. The incidence of IBD was lower in patients treated with MTX, but higher in patients treated with ETA except if ETA was combined with MTX. Also in patients on leflunomide or sulfasalazine, the IBD incidence was higher. CONCLUSIONS: In our JIA cohort, an increased IBD incidence is observed compared to the general population, and the ratio of CD to UC is markedly higher hinting at a distinct phenotype of IBD. Pretreatment with MTX seems to be protective. Treatment with ETA does not prevent IBD development and JIA patients treated with leflunomide and sulfasalazine may be at an increased risk for IBD development.

Efficacy and Safety of Sulfasalazine Suspension in Children With Ulcerative Colitis.

BACKGROUND: Sulfasalazine (SZ) is commonly used to treat pediatric ulcerative colitis (UC). SZ can be compounded into a suspension form which is beneficial for children with difficulty swallowing a pill. Despite being utilized for over 40 years, there is a lack of published data on the efficacy and safety of SZ suspension in children with UC. Recently, third-party payors have begun refusing to pay for SZ suspension due to lack of data. METHODS: In this retrospective study, we reviewed the electronic medical records of patients ages <18 years diagnosed with UC from June 1999 to December 2019 at Boston Children's Hospital and treated with SZ suspension as a first-line agent. We obtained demographics, clinical, and endoscopic data to measure outcomes at 1 year and long term. RESULTS: Of 57 patients treated with SZ suspension, 52 (91%) had a follow-up and 26 of 52 (50%) remained in steroid-free remission at 1 year. Two patients were switched to SZ tablets due to nonmedical reasons and 11 (21%) required rescue treatment (2 infliximab, 1 tacrolimus, 8 6-mercaptopurine/azathioprine) within a year. Three required colectomy within a year and 5 in long term. Four (8%) developed nonserious adverse reactions and switched to 5-aminosalicylates (5-ASA) by 1 year. The median duration of long-term follow-up was 36 months (range, 2-205 months) with 28 requiring treatment escalation in long term. CONCLUSIONS: SZ suspension is a safe and effective treatment for UC in children with difficulty swallowing a pill. The 1-year remission rate on this treatment is comparable to 5-ASA utilized in children.

Significance of 5-Aminosalicylic Acid Intolerance in the Clinical Management of Ulcerative Colitis.

BACKGROUND: Two major types of 5-aminosalicylic acid (5-ASA)-containing preparations, namely, mesalazine/5-ASA and sulfasalazine (SASP), are currently used as first-line therapy for ulcerative colitis. Recent reports show that optimization of 5-ASA therapy is beneficial for both patient outcomes and healthcare costs. Although 5-ASA and SASP have good efficacy and safety profiles, clinicians occasionally encounter patients who develop 5-ASA intolerance. SUMMARY: The most common symptoms of acute 5-ASA intolerance syndrome are exacerbation of diarrhea, fever, and abdominal pain. Patients who discontinue 5-ASA therapy because of intolerance have a higher risk of adverse clinical outcomes, such as hospital admission, colectomy, need for advanced therapies, and loss of response to anti-tumor necrosis factor (TNF) biologics. When patients develop symptoms of 5-ASA intolerance, the clinician should consider changing the type of 5-ASA preparation. Recent genome-wide association studies and meta-analyses have shown that 5-ASA allergy is associated with certain single-nucleotide polymorphisms. Although there are no modalities or biomarkers for diagnosing 5-ASA intolerance, the drug-induced lymphocyte stimulation test can be used to assist in the diagnosis of acute 5-ASA intolerance syndrome with high specificity and low sensitivity. This review presents a general overview of 5-ASA and SASP in the treatment of inflammatory bowel disease and discusses the latest insights into 5-ASA intolerance. KEY MESSAGES: 5-ASA is used as first-line therapy for ulcerative colitis. Optimization of 5-ASA may be beneficial for patient outcomes and healthcare systems. Acute 5-ASA intolerance syndrome is characterized by diarrhea, fever, and abdominal pain. Periodic renal function monitoring is recommended for patients receiving 5-ASA.

The synbiotic mixture of Bacillus licheniformis and Saccharomyces cerevisiae extract aggravates dextran sulfate sodium induced colitis in rats.

BACKGROUND: Uncertain effects of probiotics and/or prebiotics have been reported in experimental and clinical colitis. This study aims to examine the effects of a synbiotic combination comprising Bacillus licheniformis DSM 17236 and Saccharomyces cerevisiae cell wall extract on dextran sulfate sodium (DSS)-induced colitis in Sprague Dawley rats. METHODS: Acute colitis was induced in rats by oral administration of DSS 3.5% for 7 days. Fifty rats were divided equally into five groups; one control group and the other groups were induced with colitis and treated with or without the tested synbiotic, mixed with diet, for 28 days and sulfasalazine (100 mg/kg) via intragastric tube once daily for 14 days. RESULTS: Symptomatically, the synbiotic administration raised the disease activity index (DAI) to comparable scores of the DSS group, specially from the 2nd to 7th days post DSS intoxication. It also induced a significant (p < 0.05) amplification of WBCs, myeloperoxidase (MPO), malondialdehyde (MDA), nuclear factor kappa B (NF-kB) expression and proinflammatory cytokines tumor necrosis factor alpha (TNFα), interferon gamma (INFγ), and interleukin-1 beta (IL-1ß) while depressed the antioxidant enzymes glutathione peroxidase (GPx), catalase (CAT), and superoxide dismutase (SOD) when compared with the DSS and control groups. The DSS intoxicated and Synbiotic+DSS groups showed desquamations of the covering epithelium, noticeable diffuse leukocytic infiltrations, sever catarrhal enteritis, ischemic colitis with diffuse coagulative necrosis of the entire colonic mucosa. Contrarily, sulfasalazine proved to be effective in the reduction of the tested inflammatory markers and the pathological degenerative changes of the DSS ulcerative colitis. CONCLUSION: The examined synbiotic did not ameliorate but aggravated the DSS-induced colitis, so it should be subjected to intensive experimental and clinical testing before their use in animals and human.

Drug hypersensitivity syndrome induced by sulfasalazine: A case report.

INTRODUCTION: Drug hypersensitivity syndrome (DHS) induced by sulfasalazine is a serious systemic delayed adverse drug reaction, which is associated with significant morbidity and mortality. PATIENT CONCERNS: A 52-year-old man was hospitalized for developing a rash after 3 weeks of sulfasalazine treatment for ulcerative colitis (UC). DIAGNOSIS: The patient was diagnosed with DHS based on his drug history, clinical manifestations, and laboratory test results. INTERVENTIONS: The patient was administered intravenous glucocorticoids. The patient's condition improved after treatment with human immunoglobulin and antihistamines. OUTCOMES: Combination therapy of glucocorticoid and gamma globulin, the whole-body pruritus disappeared, and no new rash appeared. The whole-body rash subsided or turned dark red. CONCLUSION: This article describes the diagnosis and treatment process of a case of sulfasalazine-induced DHS and reviews the relevant literature to improve clinician understanding and avoid misdiagnosis and missed diagnosis.

Combined Conventional Synthetic Disease Modifying Therapy vs. Infliximab for Rheumatoid Arthritis: Emulating a Randomized Trial in Observational Data.

Observational studies are often considered unreliable for evaluating relative treatment effectiveness, but it has been suggested that following target trial protocols could reduce bias. Using observational data from patients with rheumatoid arthritis (RA) in the Swedish Rheumatology Quality Register (SRQ), between 2006 and 2020, we emulated the protocol of the Swedish Farmacotherapy trial (SWEFOT) and compared the results. SWEFOT was a pragmatic trial nested in SRQ, between 2002 and 2005, where methotrexate (MTX) insufficient responders were randomized to receive additional infliximab or sulfasalazine (SSZ) + hydroxychloroquine (HCQ). Patients with RA initiating infliximab (N = 313) or SSZ + HCQ (N = 196) after MTX were identified in SRQ and the Prescribed Drugs Register, mimicking the SWEFOT eligibility criteria. The primary outcome was the proportion of European Alliance of Associations for Rheumatology (EULAR) good responders at 9 months, classifying patients who discontinued treatment as "nonresponders." Through sensitivity analyses, we assessed the impact of relaxing eligibility criteria. The observed proportions reaching EULAR good response were close to those reported in SWEFOT: 39% (vs. 39% in SWEFOT) for infliximab and 28% (vs. 25%) for SSZ + HCQ. The crude observed response ratio was 1.39 (95% confidence interval (CI) 1.04-1.86), increasing to 1.48 (95% CI 0.98-2.24) after confounding adjustment, compared to 1.59 (95% CI 1.10-2.30) in SWEFOT. Results remained close to SWEFOT when relaxing eligibility criteria until allowing prior disease-modifying anti-rheumatic drug (DMARD) use which reduced the observed difference between treatments. By applying a prespecified trial emulation protocol to observational clinical registry data, we could replicate the results of SWEFOT, favoring infliximab over SSZ + HCQ combination therapy at 9 months.