The role of chest X-rays when screening for latent tuberculosis infection in patients with inflammatory bowel disease before starting biologic treatment.

BACKGROUND: Guidelines generally recommend a combination of immunological assays and chest X-ray imaging (CXR) when screening for latent tuberculosis infection (LTBI) prior to biologic treatment in inflammatory bowel disease (IBD). OBJECTIVE: To investigate whether CXR identify patients with suspected LTBI/TB who were not identified with QuantiFERON tests (QFT) when screening for LTBI/TB before starting biologic treatment in IBD patients. METHODS: Single-center, retrospective cohort study of patients with inflammatory bowel disease who had a QFT and a CXR prior to initiation of biologic treatment in a 5-year period (October 1st, 2017 to September 30th, 2022). RESULTS: 520 patients (56% female, mean age 40.1 years) were included. The majority had none or few risk factors for TB (as reflected by the demographic characteristics) but some risk factors for having false negative QFT results (concurrent glucocorticoid treatment and inflammatory activity). QFT results were positive in 8 patients (1.5%), inconclusive in 18 (3.5%) and negative in 494 (95.0%). Only 1 patient (0.19%) had CXR findings suspicious of LTBI. This patient also had a positive QFT and was subsequently diagnosed with active TB. All patients with negative or inconclusive QFT had CXR without any findings suggesting LTBI/TB. One patient developed active TB after having initiated biologic treatment in spite of having negative QFT and a normal CXR at screening. CONCLUSION: In a population with low risk of TB, the benefits of supplementing the QFT with a CXR are limited and are unlikely to outweigh the cost in both patient test-burden, radioactive exposure, and economic resources.

Withdrawal of Immunomodulators or TNF Antagonists in Patients With Inflammatory Bowel Diseases in Remission on Combination Therapy: A Systematic Review and Meta-analysis.

BACKGROUND & AIMS: Withdrawal of immunomodulators (IMMs) or tumor necrosis factor (TNF) antagonists in patients with inflammatory bowel diseases (IBDs) in remission on combination therapy is attractive. We evaluated the efficacy and safety of (1) IMM, or (2) TNF antagonist withdrawal in patients with IBD in sustained remission on combination therapy. METHODS: Through a systematic review till March 31, 2023, we identified randomized controlled trials (RCTs) that compared the efficacy and safety of IMM or TNF antagonist withdrawal vs continued combination therapy, in patients with IBD in sustained corticosteroid-free clinical remission for >6 months on combination therapy. Primary outcome was risk of relapse and serious adverse events at 12 months. We conducted meta-analysis to calculate relative risk (RR) and 95% confidence interval (CI) and used Grading of Recommendations Assessment, Development and Evaluation (GRADE) to appraise certainty of evidence. RESULTS: We identified 8 RCTs with 733 patients (77% with Crohn's disease, 91% on infliximab-based combination therapy). On meta-analysis of 5 RCTs, there was no difference in the risk of relapse between patients with IMM withdrawal (continued TNF antagonist monotherapy) vs continued combination therapy (16.8% vs 14.9%; RR, 1.15; 95% CI, 0.75-1.76) without heterogeneity (low certainty of evidence). TNF antagonist withdrawal (continued IMM monotherapy) was associated with 2.4-times higher risk of relapse compared with continuing combination therapy (31.5% vs 11.2%; RR, 2.35; 95% CI, 1.38-4.01), with minimal heterogeneity (low certainty of evidence). There was no difference in the risk of serious adverse events with IMM or TNF antagonist withdrawal vs continued combination therapy. CONCLUSIONS: In patients with IBD in sustained corticosteroid-free clinical remission for >6 months on combination therapy, de-escalation with TNF antagonist withdrawal, but not IMM withdrawal, was associated with an increased risk of relapse.

Exploring disease-related and treatment-related issues and concerns experienced by adults with spondyloarthritis, inflammatory bowel disease and psoriasis to identify unmet needs: a qualitative clinical concept mapping study.

OBJECTIVES: Exploring patients' perspectives for significant factors of relevance in living with a chronic disease is important to discover unmet needs and challenges. The primary objective of this study was to explore disease-related and treatment-related issues and concerns experienced by adults with spondyloarthropathies (SpA) and associated diseases. As a secondary objective, we wanted to explore whether these factors were generic or disease dependent. DESIGN: We used group concept mapping (GCM), a validated qualitative method, to identify disease-related and treatment-related issues and concerns. Participants generated statements in the GCM workshops and organised them into clusters to develop concepts. Furthermore, participants rated each statement for importance from 1: 'not important at all' to 5: 'of great importance'. SETTING: Participants were recruited during routine care at the outpatient clinic at the hospitals in the period from May 2018 to July 2022. PARTICIPANTS: Eligible participants were adults ≥18 years and diagnosed with axial spondyloarthritis (AxSpA), psoriatic arthritis (PsA), psoriasis (PsO) or inflammatory bowel disease -split into Crohn's disease (CD) and ulcerative colitis (UC). RESULTS: 52 patients participated in the 11 workshops divided into groups according to their diagnosis. They created a total of 1275 statements that generated 10 AxSpA concepts, 7 PsA concepts, 7 PsO concepts, 10 CD concepts and 11 UC concepts. The highest rated concepts within each disease group were: AxSpA, 'lack of understanding/to be heard and seen by healthcare professionals' (mean rating 4.0); PsA, 'medication (effects and side effects)' (mean rating 3.8); PsO, 'social and psychological problems, the shame' (mean rating 4.0); CD, 'positive attitudes' (mean rating 4.3) and UC; 'take responsibility and control over your life' (mean rating 4.0). CONCLUSION: People with SpA and associated diseases largely agree on which concepts describe their disease-related and treatment-related issues and concerns with a few of them being more disease-specific.

Identifying and understanding disease burden in patients with inflammatory bowel disease.

OBJECTIVE: Physicians tend to focus on biomedical targets while little is known about issues important to patients. We aimed to identify critical concepts impacting patients with inflammatory bowel disease (IBD). DESIGN: We performed a survey of patients with IBD in biologic therapy (n=172) and used a validated qualitative method called group concept mapping (GCM) in patient workshops. The survey included 13 questions on attitudes toward symptoms and issues related to IBD. In the eight workshops, patients (n=26) generated statements later clustered into concepts identifying issues impacting a patient's life. Patients ranked the statements. RESULTS: In the survey, patients' mean age were 40 years (SD 13), 53% were women, and 38% had ulcerative colitis. They identified fatigue (57%) and stool frequency (46%) as the most critical symptoms impacting their daily lives regardless of disease activity. In the GCM workshops with Crohn's disease (n=13) (median age 42 years (IQR 39-51) and 62% were women), 335 statements divided among 10 concepts were generated, and the three most important concepts were 'Positive attitudes', 'Accept and recognition', and 'Sharing knowledge and experiences in life with Crohn's disease'. In the workshops with ulcerative colitis (n=13) (median age 43 years (IQR 36-49) and 69% were women), 408 statements divided into 11 concepts were generated; the most important concepts were 'Take responsibility and control over your life', 'Medication', and 'Everyday life with ulcerative colitis'. CONCLUSION: Focusing solely on IBD symptoms, patients identified fatigue and stool frequency to impact daily life the most. However, when investigating the disease burden in a broader perspective beyond classic IBD symptoms, patients identified concepts with focus on emotional health to be most important. TRIAL REGISTRATION: The Copenhagen University Hospital, Herlev and Gentofte approved the questionnaire and methodology (work-zone no: 18015429).

Fatigue is a systemic extraintestinal disease manifestation largely independent of disease activity, chronicity, and nutritional deficiencies in inflammatory bowel disease on biologics.

BACKGROUND: Fatigue is a common symptom reported by patients with chronic immunoinflammatory diseases and with profound negative implications on health-related quality of life. This study aimed to delineate underlying components contributing to fatigue in patients with inflammatory bowel disease (IBD) receiving biologic therapy. METHODS: Cross-sectional questionnaire study of all patients with IBD receiving any biologic therapy at a tertiary IBD center. Fatigue was assessed by Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F). Disease activity and quality of life were evaluated by generic questionnaires. Principal component analysis (PCA) was used to identify components of variables explaining fatigue. RESULTS: Three hundred patients with IBD were included. Moderate-to-severe fatigue defined as FACIT-F ≤ 39 was present in half of the included patients. PCA condensed variables associated with fatigue into three main components contributing to 49% of observed fatigue. The first component, explaining 21% of fatigue, included factors related to disease chronicity, e.g., long disease duration, high number of previously used biologic therapies, presence of previous intestinal surgery, and increasing age. The second component explained 14% of fatigue and comprised disease activity-related aspects, e.g., disease activity indices and C-reactive protein. The third explained 14% of fatigue and comprised various nutritional deficiencies. CONCLUSION: Fatigue can partly be explained by chronicity, disease activity, and nutritional deficits. However, the cause of fatigue is unexplained in approximately half of the patients with IBD supporting that fatigue can be an independent, systemic extraintestinal disease manifestation in IBD.

A systematic monitoring approach to biologic therapies in inflammatory bowel disease: patients' and physicians' preferences and adherence.

OBJECTIVES: Treatment of patients with inflammatory bowel disease (IBD) should aim at achieving mucosal healing. However, monitoring schedules to support this goal remain undefined. We aimed to identify patients' and physicians' preferences regarding monitoring strategy and investigated the feasibility of such a strategy. METHODS: Elements considered relevant for monitoring were identified in questionnaire surveys among 1) patients with IBD receiving biologic agents (n = 172) and 2) their physicians (n = 87). Adherence to a monitoring strategy incorporating these elements was investigated in a retrospective cohort of patients with IBD treated with biologic agents (n = 139). RESULTS: Patients considered blood and stool samples, endoscopies, and magnetic resonance imaging (MRI) to be relevant aspects of monitoring their disease. However, patients also considered stool samples and endoscopies unpleasant. Physicians considered blood samples (99%), medical consultations (99%), fecal calprotectin (85%), endoscopy (78%), and MRI (71%) to be important aspects of IBD monitoring but considered endoscopies and MRI relevant only at clinical signs of relapse. A review of the clinical use of monitoring strategies including the elements identified above revealed high adherence for blood samples and disease activity indices (92%), but low adherence for fecal calprotectin (38%), therapeutic drug monitoring (38%), and endoscopies (32%). CONCLUSION: Important tools for evaluating mucosal healing (e.g., endoscopy) were rated highly unpleasant by patients, and physicians found endoscopies/MRI relevant only in case of relapse. These findings were reflected by low rates of adherence to use of these monitoring tools. In defining monitoring schedules to help achieve treatment goals, these important barriers must be addressed.

Discontinuation of Infliximab Therapy in Patients with Crohn's Disease.

BACKGROUND: Whether infliximab therapy can be successfully discontinued after patients with Crohn's disease have attained sustained, clinical, biochemical, and endoscopic remission is unknown. METHODS: We conducted a multicenter, randomized, double-blind, placebo-controlled withdrawal study of infliximab in patients with Crohn's disease who were in clinical, biochemical, and endoscopic remission after standard infliximab maintenance therapy for at least 1 year. Patients were randomly assigned 1:1 to continue infliximab therapy or to receive matching placebo for 48 weeks. The primary end point was time to relapse. RESULTS: This study randomly assigned 115 patients to either the infliximab-continuation group or to the infliximab-discontinuation group. No relapses were observed among the 59 patients continuing infliximab, whereas 23 of 56 patients discontinuing infliximab experienced relapse. Time to relapse was significantly shorter among patients who discontinued infliximab than among those who continued infliximab (hazard ratio, 0.080; 95% confidence interval [CI], 0.035 to 0.186; P<0.001). At the end of the trial at week 48, relapse-free survival was 100% in the infliximab-continuation group and 51% in the infliximab-discontinuation group. The key secondary end point, time to loss of remission, was significantly shorter among patients discontinuing infliximab therapy than those continuing infliximab (hazard ratio, 0.025; 95% CI, 0.003 to 0.187; P<0.001). No unexpected adverse events were reported. CONCLUSIONS: Discontinuation of infliximab for patients with Crohn's disease receiving long-term infliximab therapy and in clinical, biochemical, and endoscopic remission leads to a considerable risk of relapse. (Funded by the Nordic Trial Alliance [NordForsk], the Medical Fund of the Danish Regions [Regionernes Medicin og Behandlingspulje], the Danish Colitis-Crohn Association, and the A.P. Moller Foundation; ClinicalTrials.gov number, NCT01817426; EudraCT number, 2012-002702-51.)

Inflammatory bowel disease with primary sclerosing cholangitis: A Danish population-based cohort study 1977-2011.

BACKGROUND AND AIMS: Inflammatory bowel disease (IBD) may be complicated by primary sclerosing cholangitis (PSC). We aimed to assess the characteristics of Danish PSC-IBD patients and to compare their prognosis with IBD patients without PSC. METHODS: A retrospective nationwide population-based cohort of 257 PSC-IBD patients was assessed through Danish national registries and manual scrutiny of patient files. RESULTS: For all PSC-IBD patients diagnosed after 1976 (n = 222) and 8231 IBD controls (ie, without PSC), the cumulative probability of resective surgery, liver transplantation, cancer, and survival from 1977 through 2011 was estimated and compared by log-rank test and Cox regression. PSC-IBD patients primarily had ulcerative colitis (UC) (72%), were diagnosed in young adulthood (median age at IBD diagnosis, 23 years), and 9% were smokers. Among PSC-UC patients 78% had pancolitis at diagnosis. Among patients with PSC and Crohn's disease (CD) 91% had colonic involvement. The PSC-IBD patients had a significantly higher probability of receiving resective surgery (HR; 2.13, 95% CI: 1.50-3.03); of developing colorectal cancer (CRC) (HR; 21.4, 95% CI: 9.6-47.6), of cholangiocarcinoma (HR; 190, 95% CI: 54.8-660), and of dying (HR; 4.39, 95% CI: 3.22-6.00) as compared to non-PSC-IBD controls. The 25-year cumulative risk of liver transplantation was high (53%). CONCLUSIONS: This unselected population-based study shows that PSC-IBD patients not only have an extensive phenotype of IBD, they are also treated more intensively than other patients with IBD. However, the prognosis remains poor and without any apparent improvement over calendar time.

Telephone reminders reduced the non-attendance rate in a gastroenterology outpatient clinic.

INTRODUCTION: Non-attendance is a global health-care problem. The aim of the present study was 1) to investigate if a telephone reminder could reduce the non-attendance rate, 2) to study reasons for non-attendance and 3) to evaluate if a permanent implementation would be economically advantageous in a gastroenterology outpatient clinic like ours. METHODS: This was a comparative intervention study with a historical control group in a gastroenterology outpatient clinic. The study lasted six months. Patients with a scheduled appointment in the first three-month period received no reminder (control group, n = 2,705). Patients in the following three-month period were reminded by telephone one weekday in advance of their appointment, when possible (intervention group, n = 2,479). Non-attending patients in the intervention group received a questionnaire. Based on the results, a financial cost-benefit analysis was made. RESULTS: In the intervention group, 1,577 (64%) patients answered the reminder telephone call. The non-attendance rate was significantly lower in the intervention group (6.1%) than in the control group (10.5%) (p < 0.00001). Only 1.3% of the patients who answered the reminder turned out to be non-attendees. The most common explanation for non-attendance in the intervention group was forgetfulness (39%). The reminder telephone call was cost-effective. CONCLUSION: In this outpatient clinic, telephone reminders were cost-effective and significantly reduced the non-attendance rate by 43%.

Discontinuation of infliximab therapy in patients with Crohn's disease in sustained complete remission (the STOP IT study): protocol for a double-blind, randomised, placebo-controlled, multicentre trial.

INTRODUCTION: Infliximab (IFX), a monoclonal chimeric antibody against tumour necrosis factor (TNF) α, is effective for induction and maintenance of remission in moderate to severe Crohn's disease. Discontinuation of IFX maintenance therapy in patients in remission should be considered in order to reduce the potential long-term side effects and lower costs. METHODS AND ANALYSIS: This is a prospective, double-blind, randomised, placebo-controlled, multicentre study of patients with luminal Crohn's disease who have been treated with IFX for at least 1 year and are in sustained complete clinical, biochemical and endoscopic remission (ie, Crohn's Disease Activity Index (CDAI) score <150, complete mucosal healing and biochemical markers of inflammation within the normal range). These patients are randomised to receive placebo infusions or continue IFX maintenance therapy. The primary end point is the proportion of patients in maintained remission after 48 weeks (def. CDAI <150). ETHICS AND DISSEMINATION: It is estimated that the knowledge gained about how to optimally handle patients with Crohn's disease in complete long-term sustained remission on IFX is proportionate to the risks and inconveniences related to participation in this study. Prolonged exposure to IFX may cause severe side effects and increased risk of malignancies. Conversely, IFX discontinuation should not unnecessarily create a high risk of relapse. Thus, empirical evidence is needed concerning the safety of discontinuing IFX once a patient exhibits sustained remission. Study results will be published in an English language scientific medical journal. The study is approved by the Danish Medicines Agency (EudraCT-number: 2012-002702-51) and the Regional Ethics Committee of Region Hovedstaden Denmark (Approval-number: H-4-2012-099). The project is reported to the Danish Data Protection Agency (ID-number: 2007-58-0015/HEH.750.89-27), registered at Clinicaltrials.gov, and monitored by independent GCP units for the University of Copenhagen, Odense and Aarhus. The current approved protocol is V.3.2, dated 1 June 2014. TRIAL REGISTRATION NUMBER: http://clinicaltrials.gov/show/NCT01817426.

Antibodies against infliximab are associated with de novo development of antibodies to adalimumab and therapeutic failure in infliximab-to-adalimumab switchers with IBD.

BACKGROUND: A notable proportion of patients with inflammatory bowel disease (IBD) are switched from infliximab (IFX) to adalimumab (ADL). We investigated if immunogenicity of IFX influenced immunogenicity and clinical outcomes of later ADL therapy. METHODS: Single-center cohort study including all patients with IBD assessed for antibodies (Abs) against IFX or ADL. RESULTS: Anti-IFX Abs were evaluated in 187 patients treated with IFX as first line anti-TNF agent. Approximately, half (49%) were positive. Detected anti-IFX Abs had functional capacity as judged by a median IFX concentration below limit of detection (interquartile range, 0.0-0.0 µg/mL) versus 3.8 µg/mL (IQR, 1.3-7.9) in anti-IFX Ab-negative patients, P < 0.0001; but did not cross-react with ADL. Anti-ADL Abs were assessed in 57 ADL-treated patients. Twelve (21%) tested positive. Patients with previous anti-IFX Ab development were significantly more prone to develop anti-ADL Abs (33%) than those without (0%): odds ratio estimated 11, P = 0.04. The anti-ADL Abs were also functional because ADL was undetectable in all anti-ADL Ab-positive patients versus median 8.3 µg/mL (IQR 5.0-11.0) in anti-ADL-negative patients, P < 0.0001. The presence of anti-ADL Abs increased the risk of secondary ADL treatment failure with OR 28 (3-248), P < 0.001. ADL trough levels, irrespectively of anti-ADL Ab status, associated with efficacy of ADL maintenance therapy: AUC(ROC) 0.77 (0.62-0.93), P < 0.01. CONCLUSIONS: Switchers with anti-IFX Abs are prone to develop de novo anti-ADL Abs, which may result in therapeutic failure. Assessment of ADL immunogenicity in anti-IFX Ab-positive switchers is required to ensure optimal interventions at inadequate treatment responses and to avoid inappropriate ADL intensification regimens.

Individualised therapy is more cost-effective than dose intensification in patients with Crohn's disease who lose response to anti-TNF treatment: a randomised, controlled trial.

OBJECTIVE: Although the reasons for secondary loss of response to infliximab (IFX) maintenance therapy in Crohn's disease vary, dose intensification is usually recommended. This study investigated the cost-effectiveness of interventions defined by an algorithm designed to identify specific reasons for therapeutic failure. DESIGN: Randomised, controlled, single-blind, multicentre study. 69 patients with secondary IFX failure were randomised to IFX dose intensification (5 mg/kg every 4 weeks) (n=36) or interventions based on serum IFX and IFX antibody levels using the proposed algorithm (n=33). Predefined co-primary end points at week 12 were proportion of patients responding (Crohn's Disease Activity Index (CDAI) decrease ≥ 70, or ≥ 50% reduction in active fistulas) and accumulated costs related to treatment of Crohn's disease, expressed as mean cost per patient, based on the Danish National Patient Registry for all hospitalisation and outpatient costs in the Danish healthcare sector. RESULTS: Costs for intention-to-treat patients were substantially lower (34%) for those treated in accordance with the algorithm than by IFX dose intensification: € 6038 vs € 9178, p<0.001. However, disease control, as judged by response rates, was similar: 58% and 53%, respectively, p=0.81; difference 5% (-19% to 28%). For per-protocol patients, treatment costs were even lower (56%) in the algorithm-treated group (€ 4062 vs € 9178, p<0.001) and with similar response rates (47% vs 53%, p=0.78; difference -5% (-33% to 22%)). CONCLUSIONS: Treatment of secondary IFX failure using an algorithm based on combined IFX and IFX antibody measurements significantly reduces average treatment costs per patient compared with routine IFX dose escalation and without any apparent negative effect on clinical efficacy. TRIAL REGISTRATION NO: NCT00851565.

Outcome after discontinuation of infliximab in patients with inflammatory bowel disease in clinical remission: an observational Danish single center study.

OBJECTIVE: To investigate duration of remission, including risk factors for relapse and response to retreatment with infliximab (IFX), in patients with Crohn's disease (CD) and ulcerative colitis (UC) who had discontinued IFX while in clinical remission. METHODS: Observational, single-center, retrospective study of all patients with a primary response to IFX who discontinued IFX therapy while in steroid-free remission. Relapse was defined as reintroduction of treatment with a biologic, systemic steroid or surgery. RESULTS: Of 219, 53 (24%) CD patients, and 28 of 97 (30%) UC patients discontinued IFX while in clinical steroid-free remission. The proportion of patients in remission declined steadily with 61% of CD patients, and 75% of UC patients being in remission after 1 year. Half the patients maintained remission after median 2 years (680 days (412-948)) and 3.5 years (1334 days (995-1673)), respectively; p = 0.057. Twelve percent with CD and 40% with UC were in remission at the end of follow-up after 10 and 4.5 years, respectively. Longer disease duration was associated with relapse in univariate analysis in CD, OR 1.1 (1.0-1.1), p = 0.022. Of 25, 24 CD patients (96%), and 5 of 7 UC patients (71%) experienced complete clinical remission when retreated with IFX after relapse. CONCLUSION: While the short-term prognosis seems favorable, the majority of patients who discontinue IFX while in remission relapse over time. The response to retreatment with IFX at relapse seems favorable in this subpopulation.

Acute and delayed hypersensitivity reactions to infliximab and adalimumab in a patient with Crohn's disease.

A 61 year old woman with active luminal Crohn's disease was successfully treated with infliximab induction therapy followed by 5 infusions every 8 weeks. However, symptoms returned in the weeks preceding the 7th and 8th infusions. The 9th infusion was therefore given only 4 weeks after the 8th infusion, but an acute severe anaphylactoid reaction occurred immediately after start of the infusion. Anti-infliximab IgG antibody concentration was high (100 U/ml) prior to the 8th infusion and up to 1 year after infliximab discontinuation (81 U/ml). Anti-infliximab IgE antibodies were not found, and the anti-infliximab antibodies did not cross react with adalimumab. One week after the anaphylactoid reaction to infliximab, adalimumab therapy was initiated. Twelve days after the first adalimumab administration (80 mg), a delayed hypersensitivity reaction occurred. This was likely caused by rapidly generated anti-adalimumab IgG antibodies (45 U/ml), as these antibodies appeared to be specific for adalimumab in that infliximab failed to compete with adalimumab/anti-adalimumab antibody binding ex vivo. In conclusion, immunogenicity to infliximab and adalimumab may be associated with both acute anaphylactoid reactions and delayed hypersensitivity reactions. Reactions may be precipitated by newly induced specific anti-drug antibodies rather than by cross-reactivity of previously generated antibodies.

Cut-off levels and diagnostic accuracy of infliximab trough levels and anti-infliximab antibodies in Crohn's disease.

INTRODUCTION: Reasons for infliximab failure in Crohn's disease and ulcerative colitis are debated. Serum levels of infliximab and anti-infliximab antibodies have been associated with loss of response. We aimed at determining cut-off levels for infliximab and anti-infliximab antibody concentrations associated with clinical response to infliximab maintenance therapy. METHODS: Patients with inflammatory bowel disease (n = 106) were retrospectively classified as having maintained response or loss of response to infliximab maintenance therapy. Trough concentrations were measured by fluid-phase radioimmunoassays. RESULTS: Infliximab levels were significantly lower, and anti-infliximab antibody levels significantly higher, in Crohn's disease patients with loss of response (median infliximab 0 µg/ml, median anti-infliximab antibodies 35 U/ml) compared to patients with maintained response (median infliximab 2.8 µg/ml, median anti-infliximab antibodies 0 U/ml; p < 0.0001). Receiver operating characteristic (ROC) analysis identified optimal cut-off values: infliximab <0.5 µg/ml, which was associated with loss of response with sensitivity 86% [64-97] and specificity 85% [72-94]; and anti-infliximab antibodies ≥10 U/ml yielding a sensitivity of 81% [61-93] and specificity 90% [79-96]. Combined measurements of infliximab and anti-infliximab antibodies using these cut-off values had higher accuracy yielding a sensitivity of 81% [57-94] and specificity 94% [82-98]. Similar pattern was observed in a smaller cohort of patients with ulcerative colitis. CONCLUSIONS: Combined measurements of infliximab and anti-infliximab antibodies using cut-off levels provided high accuracy for discriminating between clinical response types to infliximab maintenance therapy. Cut-off levels are considered a prerequisite to further investigations of clinical usefulness of measurements of infliximab and anti-infliximab antibodies in patients failing infliximab therapy.