Longstanding Phenytoin Use as a Cause of Progressive Dyspnea.

CASE PRESENTATION: A 54-year-old South African man with a medical history of type 2 diabetes mellitus, seizure disorder, OSA, and latent TB presented to the ER with gradually progressive dyspnea over months. He also reported occasional dry cough and fatigue at presentation but denied fever, chills, chest pain, leg swelling, palpitations, or lightheadedness. He was treated with a course of levofloxacin for presumed community-acquired pneumonia as an outpatient without improvement and had tested negative for COVID-19. He denied occupational or environmental exposures or sick contacts, though he had traveled back to South Africa 1 year before presentation. He had complex partial seizures for the past 22 years, which had been well controlled on phenytoin (300 mg daily). His other home medications included dulaglutide, sertraline, and atorvastatin and had no recent changes. He quit smoking 30 years ago after smoking one pack per day for 10 years.

Adverse Events of Thiopurine Therapy in Pediatric Inflammatory Bowel Disease and Correlations with Metabolites: A Cohort Study.

BACKGROUND: In the recent era of growing availability of biological agents, the role of thiopurines needs to be reassessed with the focus on toxicity. AIMS: We assessed the incidence and predictive factors of thiopurine-induced adverse events (AE) resulting in therapy cessation in pediatric inflammatory bowel disease (IBD), related to thiopurine metabolites and biochemical abnormalities, and determined overall drug survival. METHODS: We performed a retrospective, single-center study of children diagnosed with IBD between 2000 and 2019 and treated with thiopurine therapy. The incidence of AE and overall drug survival of thiopurines were evaluated using the Kaplan-Meier method. Correlations between thiopurine metabolites and biochemical tests were computed using Spearman's correlation coefficient. RESULTS: Of 391 patients with IBD, 233 patients (162 Crohn's disease, 62 ulcerative colitis, and 9 IBD-unclassified) were prescribed thiopurines (230 azathioprine and 3 mercaptopurine), of whom 50 patients (22%) discontinued treatment, at least temporary, due to thiopurine-induced AE (median follow-up 20.7 months). Twenty-six patients (52%) were rechallenged and 18 of them (70%) tolerated this. Sixteen patients (6%) switched to a second thiopurine agent after azathioprine intolerance and 10 of them (63%) tolerated this. No predictive factors for development of AE could be identified. Concentrations of 6-thioguanine nucleotides (6-TGN) were significantly correlated with white blood cell and neutrophil count, 6-methylmercaptopurine (6-MMP) concentrations with alanine aminotransferase and gamma-glutamyltranspeptidase. CONCLUSIONS: Approximately 20% of pediatric patients with IBD discontinued thiopurine treatment due to AE. A rechallenge or switch to mercaptopurine is an effective strategy after development of AE. Concentrations of 6-TGN and 6-MMP are associated with biochemical abnormalities.

Lymphoma in Pediatric-Onset Inflammatory Bowel Disease Treated with Infliximab Monotherapy: A Case Series.

BACKGROUND: Inflammatory bowel diseases (IBD) are often treated with anti-tumor necrosis factor alpha (anti-TNFα) medications. Concomitant treatment of IBD with anti-TNFα agents and immunomodulators appears to be associated with an increased risk for lymphoma. METHODS: Patients who developed lymphoma while on monotherapy with an anti-TNFα agent were identified at three centers. Institutional Review Board approval was obtained. RESULTS: Five adolescents and young adult patients with pediatric-onset IBD who were treated with infliximab (IFX) without exposure to thiopurines were subsequently diagnosed with lymphoma. Three of the five patients had bone involvement at presentation. Epstein-Barr virus was positive in 2 cases. Median time from diagnosis of IBD and exposure to IFX prior to diagnosis of lymphoma was 5 and 4.3 years, respectively. CONCLUSIONS: This case series reports long-term follow-up for young patients with IBD who were treated with IFX monotherapy and developed lymphoma. Three of the five patients had bone involvement. In general, the risk of lymphoma following exposure to anti-TNFα medications alone remains low, but the incidence of primary bone lymphomas in IBD has not been reported. Studies examining longer exposure times may be needed to determine the true lymphoma risk in patients treated with IFX monotherapy.

Absolute and Dose-Adjusted Serum Concentrations of Clozapine in Patients Switching vs. Maintaining Treatment: An Observational Study of 1979 Patients.

BACKGROUND: Clozapine is an effective drug for the management of schizophrenia that has not responded to other agents, but some patients experience insufficient or adverse effects and discontinue treatment. OBJECTIVE: We investigated a potential association between clozapine serum concentrations and switching to other antipsychotics in a large real-world patient population from a therapeutic drug monitoring service. METHODS: Absolute and dose-adjusted serum concentrations (concentration-to-dose ratios [C/D ratios]) of clozapine during dosing between 100 and 1000 mg/day were measured in 1979 Norwegian patients during the period 2005-2019. These variables were compared in patients switching to other antipsychotic drugs versus maintaining clozapine treatment using linear mixed models. Smoking habits were known for 49% of the patients. To prevent potential nonadherence affecting clozapine switching, only patients with serum concentrations above 50% of the lower reference range were included. RESULTS: In total, 190 patients (9.6%) switched from clozapine to another antipsychotic drug during the study period, whereas the remaining patients were not detected as switchers and were interpreted as maintaining treatment. Patients switching treatment had 23.5% lower absolute concentrations (954 vs. 1245 nmol/L; p < 0.001) and 15.7% lower daily doses (305 vs. 362 mg/day; p < 0.001) of clozapine than did nonswitchers, making the clozapine C/D ratio 9.7% lower in switchers than in nonswitchers after correcting for smoking habits (2.80 vs. 3.10 nmol/L/mg/day; p = 0.032). CONCLUSIONS: The present study suggests that decreased absolute and dose-adjusted serum concentrations of clozapine were associated with clozapine discontinuation. The significantly reduced clozapine concentrations regardless of prescribed dose in switchers versus nonswitchers may indicate a pharmacokinetic mechanism underlying the risk of clozapine discontinuation.

Golimumab in juvenile idiopathic arthritis-associated uveitis unresponsive to Adalimumab.

OBJECTIVE: To assess the efficacy of golimumab (GLM) as a treatment option for juvenile idiopathic arthritis (JIA)-associated uveitis refractory to adalimumab (ADA). METHODS: Retrospective single-centre study including patients with JIA receiving GLM for active uveitis after failing ADA. JIA- and uveitis-related data, including intraocular inflammation, best-corrected visual acuity, corticosteroid-sparing potential, and ocular complications were evaluated at start of GLM treatment, at 1 month and 3 months, and every 3 months thereafter during GLM administration. We further investigated the association of response to GLM with primary and secondary failure of ADA treatment. RESULTS: Ten patients were studied, all female (17 affected eyes, mean age 14.3 + 6.7 yrs., mean follow-up 25.2 + 21.7 mos). Two patients were switched to GLM because of primary non-response to ADA. Eight were switched because of loss of response (LOR). In 5 of the latter LOR was associated with neutralizing anti-ADA-antibodies. Response to GLM was observed in all 8 patients with LOR, while the 2 patients with primary non-response to ADA also did not respond to GLM. Three of the 8 responders experienced LOR. At the end of follow-up 4 of the 5 remaining responders had achieved complete response. One had achieved partial response. CONCLUSION: GLM is an efficacious therapeutic option in patients who experience LOR to ADA. Our data indicate that patients without primary response to ADA should be rather switched to a biologic agent with a different mode of action instead of further blocking the TNF-alpha pathway.

Effectiveness of angiotensin-neprilysin inhibitor treatment versus renin-angiotensin system blockade in older adults with heart failure in clinical care.

OBJECTIVE: To evaluate the effectiveness of angiotensin receptor-neprilysin inhibitor (ARNI) versus renin-angiotensin system (RAS) blockade alone in older adults with heart failure with reduced ejection fraction (HFrEF). METHODS: We conducted a cohort study using US Medicare fee-for-service claims data (2014-2017). Patients with HFrEF ≥65 years were identified in two cohorts: (1) initiators of ARNI or RAS blockade alone (ACE inhibitor, ACEI; or angiotensin receptor blocker, ARB) and (2) switchers from an ACEI to either ARNI or ARB. HR with 95% CI from Cox proportional hazard regression and 1-year restricted mean survival time (RMST) difference with 95% CI were calculated for a composite outcome of time to first worsening heart failure event or all-cause mortality after adjustment for 71 pre-exposure characteristics through propensity score fine-stratification weighting. All analyses of initiator and switcher cohorts were conducted separately and then combined using fixed effects. RESULTS: 51 208 patients with a mean age of 76 years were included, with 16 193 in the ARNI group. Adjusted HRs comparing ARNI with RAS blockade alone were 0.92 (95% CI 0.84 to 1.00) among initiators and 0.79 (95% CI 0.74 to 0.85) among switchers, with a combined estimate of 0.84 (95% CI 0.80 to 0.89). Adjusted 1-year RMST difference (95% CI) was 4 days in the initiator cohort (-1 to 9) and 12 days (8 to 17) in the switcher cohort, resulting in a pooled estimate of 9 days (6 to 12) favouring ARNI. CONCLUSION: ARNI treatment was associated with lower risk of a composite effectiveness endpoint compared with RAS blockade alone in older adults with HFrEF.

Cycling or swap biologics and small molecules in psoriatic arthritis: Observations from a real-life single center cohort.

ABSTRACT: During the last years there has been an increasing availability of drugs (biologics and small molecules) with different mechanisms of action (MoA) in psoriatic arthritis (PsA). New issues about treatment strategies have arisen. The main aim of this study is to verify if there is a difference in terms of clinical efficacy (i.e. retention rate) between cycling (i.e. treating patients with the same MoA after the failure of the previous one) or swap (i.e choosing drugs with a MoA different from the failed previous one) strategies in PsA.In this mono-centric medical records review study, PsA patients treated with biologics, apremilast or tofacitinib were enrolled. Every prescription was clustered in three groups: cycling (CG), swap (SG) or first line group (1LG). Kaplan-Meier analysis and Cox test estimated and compared drugs' retention rate in CG, SG and 1LG. P < .05 was considered statistically significant.One hundred eighty-three PsA patients were enrolled (9967 patient-months). In CG and 1LG the more prescribed drugs were tumor necrosis factor inhibitor (respectively 99% and 89%), in SG interleukin 17 inhibitor (60%). There were no differences in terms of sex, age, disease duration, and retention rate between CG and SG. The 18-months retention rate of 1LG, SG and CG was 77%, 60%, and 51% respectively. The CG retention rate was lower than in 1LG (P = .03).The findings of this study suggest that in PsA the swap strategy gives no remarkable advantage compared to cycling. However, patients undergoing swap strategy may experience the same failure rate observed in naives.

Exit Strategies in Natalizumab-Treated RRMS at High Risk of Progressive Multifocal Leukoencephalopathy: a Multicentre Comparison Study.

The main aim of the study is to evaluate the efficacy and safety profile of ocrelizumab (OCR), rituximab (RTX), and cladribine (CLA), employed as natalizumab (NTZ) exit strategies in relapsing-remitting multiple sclerosis (RRMS) patients at high-risk for progressive multifocal leukoencephalopathy (PML). This is a multicentre, retrospective, real-world study on consecutive RRMS patients from eleven tertiary Italian MS centres, who switched from NTZ to OCR, RTX, and CLA from January 1st, 2019, to December 31st, 2019. The primary study outcomes were the annualized relapse rate (ARR) and magnetic resonance imaging (MRI) outcome. Treatment effects were estimated by the inverse probability treatment weighting (IPTW), based on propensity-score (PS) approach. Additional endpoint included confirmed disability progression (CDP) as measured by Expanded Disability Status Scale and adverse events (AEs). Patients satisfying predefined inclusion and exclusion criteria were 120; 64 switched to OCR, 36 to RTX, and 20 to CLA. Patients from the 3 groups did not show differences for baseline characteristics, also after post hoc analysis. The IPTW PS-adjusted models revealed that patients on OCR had a lower risk for ARR than patients on CLA (ExpBOCR 0.485, CI 95% 0.264-0.893, p = 0.020). This result was confirmed also for 12-month MRI activity (ExpBOCR 0.248 CI 95% 0.065-0.948, p = 0.042). No differences were found in other pairwise comparisons (OCR vs RTX and RTX vs CLA) for the investigated outcomes. AEs were similar among the 3 groups. Anti-CD20 drugs were revealed to be effective and safe options as NTZ exit strategies. All investigated DMTs showed a good safety profile.

Switching to aflibercept versus continuing bevacizumab for treatment-resistant neovascular age-related macular degeneration: a one-year comparative observational study.

PURPOSE: To compare outcomes of a treatment algorithm that allows for switching treatment-resistant neovascular age-related macular degeneration (nAMD) eyes to aflibercept with continuing bevacizumab. METHODS: Retrospective study of nAMD patients who initiated treatment in 2012 (aflibercept unavailable) and 2018 (aflibercept available). Eyes were included in the case of residual macular fluid after a minimum of 4 monthly bevacizumab injections. Only eyes in the 2018 group could then switch to aflibercept. RESULTS: The study included 40 eyes from 2012 and 88 eyes from 2018. Patient characteristics were similar across the groups at baseline and 4 months. In 2018, 59 eyes (67%) were switched to aflibercept after 4 months. Mean change in BCVA from 4 months to one year was +2.8 letters in 2018 versus -1.7 letters in 2012 (p = 0.043). Mean change in BCVA from baseline to one year was +9.4 letters in 2018 (p < 0.001) and +4.4 letters in 2012 (p = 0.073). Mean change in CRT from 4 months to one year was -36 µm in 2018 versus -23 µm in 2012 (p = 0.373). Mean change in CRT from baseline to one year was -100 µm in 2018 (p < 0.001) and -75 µm in 2012 (p < 0.001). Mean number of injections given in one year was 11.8 in 2018 versus 10.4 in 2012 (p < 0.001). After one year, a majority of eyes in both groups still received treatment at 4-week intervals. CONCLUSION: The study suggests that the possibility of switching eyes with treatment-resistant nAMD to aflibercept leads to a modest visual benefit compared with continuing first-line bevacizumab therapy.

A Very Short Course of HBIg+NA Followed by Entecavir or Tenofovir Monotherapy Prevents HBV Recurrence in Low-Risk Liver Transplant Recipients.

BACKGROUND: Monoprophylaxis with third-generation nucleos(t)ide analogues (NAs) can be safely adopted in hepatitis B virus (HBV)-positive, liver transplantation (LT) patients after at least 6 months of HBV immunoglobulin (HBIg)+NA. We investigated the efficacy of earlier initiation of post-LT entecavir (ETV) or tenofovir (TDF) monoprophylaxis. METHODS: Between September 2011 and January 2017, all consecutive hepatitis B surface antigen (HBsAg)-positive transplanted patients were scheduled to receive HBIg with ETV or TDF for a period related to the risk for HBV reinfection: 1. low-risk patients (HBeAg-negative and HBV DNA < 12 IU/mL before LT) were due to withdraw from HBIg once HBsAg had become negative after a minimum of 7 days of HBIg+NA; 2. high-risk patients were due to receive HBIg for at least 6 months, after which they continued with third-generation NA monotherapy, only. RESULTS: Twenty patients with a median interquartile range (IQR) follow-up of 46 (64-39) months were enrolled in the study (40% receiving ETV, 60% receiving TDF). Two low-risk patients refused early HBIg withdrawal and were therefore treated and analyzed along with the high-risk group. Eventually, there were 2 groups: group A, which included 12 low-risk patients, and group B, which included 8 patients (six high-risk, 2 low-risk). After transplantation, group A and B patients received HBIg+NA for a median (IQR) time of 7 (9-7) days and 9 (13-5) months, respectively. All 20 recipients demonstrated HBV DNA < 12 IU/mL and stable graft function during follow-up. Two patients (10%), 1 from each group, had HBsAg relapse. Notably, both patients who relapsed had hepatocellular carcinoma (HCC) diagnosed before LT and showed very low levels (< 0.25 IU/mL) of HBsAg after recurrence. CONCLUSION: In low-risk HBsAg-positive recipients, HBIg may be safely discontinued within 2 weeks of LT and replaced by ETV or TDF monotherapy.

US rheumatologists' beliefs and knowledge about biosimilars: a survey.

OBJECTIVES: We sought to evaluate perceptions of biosimilar products among US rheumatologists who prescribe TNF-α inhibitors, given that 10 TNF-α inhibitor biosimilars and two rituximab biosimilars have Food and Drug Administration (FDA) approval. METHODS: A 19-question self-administered online survey was conducted from 6 May to 1 June 2019, and fielded by WebMD, LLC. Rheumatologists (n = 9050) who were members of Medscape.com and its partner panels were invited to participate. Likert and other rating scales were used to collect responses, which were summarized descriptively. RESULTS: Responses were obtained from 320 board-certified US rheumatologists, 85% of whom were fellows of the ACR. Nearly all respondents were familiar with the FDA definition of a biosimilar product and were aware that an infliximab biosimilar was FDA approved; fewer realized that adalimumab, etanercept and rituximab biosimilars were also FDA approved. Most respondents (84%) were aware that an approved biosimilar was not automatically deemed interchangeable by the FDA. Rheumatologists were more likely to initiate biosimilar treatment for a biologic treatment-naïve patient with RA (73%) than they were to switch to the biosimilar for a patient with RA doing well on the reference product (35%). CONCLUSIONS: The results of this survey suggest that US rheumatologists have a good understanding and acceptance of biosimilar products, particularly for the initiation of treatment in biologic-naïve individuals. They were hesitant to switch from a reference product to a biosimilar for a patient doing well on the reference product. Additional education on biosimilars is required to help inform treatment decisions by rheumatologists. A plain language summary of this article has been uploaded as supplementary material, available at Rheumatology online.

[Treatment switch in diabetic macular edema: Literature review and management algorithm]. / Les switchs de traitement dans l'œdème maculaire diabétique : revue de la littérature et algorithme de prise en charge.

Initial management of diabetic macular edema (DME) is well-defined, but there is a lack of national or international consensus for patients who do not respond or respond only partially to these treatments. Several studies, mostly retrospective, have assessed medication switches, but currently, the literature contains no randomized studies. The goal of this article is to present an algorithm for switching medications, which can be proposed to DME patients treated with anti-VEGF agents, as defined by a group of French retina experts, supported by the existing literature on the subject. After initiation of an anti-VEGF treatment for DME, the response is usually assessed after 5 monthly injections. A partial anatomical response (reduction of central retinal thickness between 10 and 20%), seen in 30 to 40% of patients, is associated with a favorable visual prognosis according to randomized studies. Continuation of the anti-VEGF injections after the induction phase is thus possible. If the response remains incomplete after 3 additional anti-VEGF injections, a complete ophthalmologic examination should be performed, and a switch to another therapeutic class (corticosteroids) may be proposed in the absence of contraindications. If a complete non-response is seen initially (reduction of central retinal thickness<10%), the switch is proposed immediately after the induction phase.

Failure of anti Interleukin-1 ß monoclonal antibody in the treatment of recurrent pericarditis in two children.

BACKGROUND: Recurrent pericarditis (RP) is a complication (15-30%) of acute pericarditis with an unknown etiology. Treatment regimen consists of a combination of non-steroidal anti-inflammatory drugs (NSAIDs) and colchicine, with the addition of corticosteroids in resistant or intolerant cases. In the last decade anakinra was shown as an effective treatment in patients with colchicine resistant and steroid-dependent RP, initially in anecdotal reports in children and more recently in a randomized trial. Canakinumab is a monoclonal antibody selectively blocking IL-1ß and its use is only anecdotally reported to treat pericarditis. We report two pediatric patients with refractory recurrent pericarditis, who presented an optimal response to anakinra treatment but prompt relapse after switch to canakinumab. CASE PRESENTATION: The first patient is a girl with Recurrent Pericarditis started in April 2015, after heart surgery. NSAIDs and oral steroids were started, with prompt relapse after steroid suspension. The child showed a steroid-dependent RP; anakinra was therefore started with excellent response, but discontinued after 2 weeks for local reactions. In July 2016 therapy with canakinumab was started. She experienced four relapses during canakinumab therapy despite dosage increase and steroid treatment. In January 2018 a procedure of desensitization from anakinra was performed, successfully. Anakinra as monotherapy is currently ongoing, without any sign of flare. The second patient is a girl with an idiopathic RP, who showed an initial benefit from NSAIDs and colchicine. However, 10 days after the first episode a relapse occurred and therapy with anakinra was established. Two months later, while being in complete remission, anakinra was replaced with canakinumab due to patient's poor compliance to daily injections. She experienced a relapse requiring steroids 10 days after the first canakinumab injection. Anakinra was subsequently re-started with complete remission, persisting after 24 months follow-up. CONCLUSIONS: We describe two cases of failure of the treatment with anti-IL-1ß monoclonal antibodies in steroid- dependent idiopathic RP. This anecdotal and preliminary observation suggests a different efficacy of the two IL-1 blockers in the management of RP and support a possible pivotal role of IL-1α in the pathogenesis of this condition.

Ranibizumab non-response in pachychoroid neovasculopathy: Effects of switching to aflibercept.

Non-response to intravitreal ranibizumab represents a frequent problem in pachychoroid neovasculopathy (PNV). To investigate the effectivity of switching to aflibercept, the database of the Ludwig Maximilians University, Munich, was screened for patients fulfilling the following inclusion criteria: (i) diagnosis of PNV; (ii) inadequate response to ≥ 3 ranibizumab injections, in spite of monthly dosing, defined as persistence of subretinal-fluid four weeks after the last ranibizumab injection; (iii) resulting switch to aflibercept administered as three monthly injections. Primary outcome measure was percentage of eyes with a dry macula four weeks after the third aflibercept injection. Secondary outcome measures included changes in maximum subretinal fluid (SRF), central subfield thickness (CST) and subfoveal choroidal thickness (SFCT). In total, 14 eyes of 14 patients were included. Mean age was 64.1 ± 7.5 (range: 51-78) years. Switching to aflibercept was performed after mean 8.4 ± 4.1 (3-15) ranibizumab injections. While no eye (0%) achieved a dry macula status during ranibizumab treatment, switching to aflibercept achieved a dry macula status in eight eyes (57.1%) after three injections. While both ranibizumab and aflibercept showed an effect on CST (p = 0.027, p = 0.003), only aflibercept showed a significant effect on SRF (p = 0.0009) and SFCT (p = 0.044). In cases of PNV not responding to intravitreal ranibizumab, switching treatment to aflibercept induces a favorable short-term response resolving persistent fluid and achieving a dry macula. Further studies with longer follow-up are warranted.

Switch from branded to generic imatinib: impact on molecular responses and safety in chronic-phase chronic myeloid leukemia patients.

Since July 2017, different generic imatinib formulations have been introduced in Italy for the treatment of patients with chronic myeloid leukemia (CML). We analyzed 168 chronic phase CML patients treated with branded imatinib for a median of 12 years (range 1-16) at a single institution who switched to a single generic formulation in order to assess the safety and impact on molecular response. The Sokal risk was low/intermediate/high in 63%, 33%, and 4% of patients, respectively. The median duration of generic imatinib treatment was 19 months (range 4-22). Twenty-seven percent of patients were in MMR and 73% were in deep molecular responses (MR4-4.5) at the time of the switch. After 12 months of treatment with generic imatinib, 140 patients were evaluable for response: 23.6% and 76.4% were respectively in MMR and in deep molecular response. When the degree of response was compared with the best molecular response observed with branded imatinib, it was found that 84% of patients maintained the response previously achieved, 6% improved it, and 10% of patients had a molecular fluctuation from the previous deep molecular response to MMR. Only 1 patient lost the MMR and no patient switched to another TKI for inefficacy. In terms of safety, 20% of patients reported new or worsening side effects, but only 2 patients returned to branded imatinib for toxicity. Our data show that the switch to generic imatinib in patients who have been previously treated with branded imatinib appears to maintain efficacy, although a proportion of patients experience new or worsening side effects.

Switching to a Second Thiopurine in Adult and Elderly Patients With Inflammatory Bowel Disease: A Nationwide Study From the ENEIDA Registry.

BACKGROUND AND AIMS: Although commonly used in inflammatory bowel disease [IBD], thiopurines frequently cause intolerance, and switching to a second thiopurine has only been reported in some small series. Ours aims in this study were to evaluate the safety of switching to a second thiopurine in a large cohort, and to assess the impact of age on tolerance. METHODS: Adult IBD patients from the ENEIDA registry, who were switched to a second thiopurine due to adverse events [excluding malignancies and infections], were identified. At the beginning of thiopurine treatment, patients were divided by age into two groups: 18-50 and over 60 years of age. The rate and concordance of adverse events between the first and second thiopurines, treatment intolerance, and persistence with the second thiopurine were evaluated. RESULTS: A total of 1278 patients [13% over 60 years of age] were switched to a second thiopurine. At 12 months, the cumulative probability of switch intolerance was 43%, and persistence with treatment was 49%. Independent risk factors of switch intolerance were age over 60 years (odds ratio [OR] 1.49; 95% confidence interval [CI] 1.07-2.07; p = 0.017) , previous gastrointestinal toxicity [OR 1.4; 95% CI 1.11-1.78; p = 0.005], previous acute pancreatitis [OR 6.78; 95% CI 2.55-18.05; p <0.001], and exposure to the first thiopurine <6 months [OR 1.59; 95% CI 1.14-2.23; p = 0.007]. CONCLUSIONS: In a large series in clinical practice, switching to a second thiopurine proved to be a valid strategy. Tight monitoring of elderly IBD patients switching to a second thiopurine because of adverse events is recommended.