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.)

sEMG-Based Hand Movement Regression by Prediction of Joint Angles With Recurrent Neural Networks.

This work takes a step towards a better biosignal based hand gesture recognition by investigating the strategies for a reliable prediction of hand joint angles. Those strategies are especially important for medical applications in order to achieve e.g. good acceptance of hand prostheses among amputees. A recurrent neural network with a small footprint is deployed to estimate the joint positions from surface electromyography data measured at the forearm. As the predictions are expected to be not smooth, different post processing methods and a regularisation term for the objective function of the network are proposed. The experiments were conducted on publicly available databases. The results reveal that both post processing strategies and regularisation have a positive impact on the results with a maximal relative improvement of 6.13 %. On the one hand post processing strategies introduce an additional delay, consequently, the improvement is analysed in context of the caused delay. On the other hand the regularisation strategy does not cause a delay and can be adjusted easily to cope with different ground truths or compensate for certain problems in the hand tracking.

Persistence of antibodies to pneumococcal conjugate vaccine compared to polysaccharide vaccine in patients with Crohn's disease - one year follow up.

Background: Patients suffering from Crohn's disease (CD) are at increased risk of infectious diseases, such as pneumococcal infection. The risk increases with immunotherapy. Pneumococcal infection can be prevented by vaccination. Methods: We conducted a randomized trial of the 23-valent pneumococcal polysaccharide vaccine (PPV23) and the 13-valent pneumococcal conjugated vaccine (PCV13) in groups of CD patients treated with immunosuppressive (IS) drugs in the form of thiopurines (PPV23 n = 28, PCV13 n = 28) alone or in combination with TNF-α antagonists (PPV23 n = 13, PCV13 n = 13) and CD patients not treated with any of these drugs (untreated) (PPV23 n = 30, PCV13 n = 24). In this article, we report the immunogenicity of PPC23 and PCV13 one year after vaccination. Results: No overall differences in vaccine-induced serotype-specific immunoglobulin G (IgG) antibodies or functional antibodies (opsonophagocytic activity (OPA)) were found between the two vaccines. PCV13 induced a higher concentration of IgG antibodies for serotype 9V than PPV23 in untreated patients. In contrast, PPV23 induced higher OPA for serotypes 6B and 19F than PCV13 in IS treated patients. Untreated patients showed generally higher IgG and OPA antibody levels than patients treated with IS and TNF-α antagonists. Conclusions: In conclusion, we found no general differences in the persistence of induced antibodies when comparing PPV23 with PCV13 regardless of treatment and also within treatment groups (IS, IS + TNF-α and untreated). This was demonstrated for both serotype-specific IgG antibodies and as functional antibodies (OPA). Patients treated with thiopurines in combination with TNF-α inhibitors have an impaired immune response against both PPV23 and PCV13, as compared to untreated patients. This study has been registered in the European Clinical Trials Database (EudraCT, record no 2012-002867-86) and ClinicalTrials.gov (record no. NCT01947010).

Outcomes After Primary Infliximab Treatment Failure in Inflammatory Bowel Disease.

BACKGROUND: Primary infliximab treatment failure is common in patients with inflammatory bowel disease and represents a challenge to clinicians. Treatment options are limited. This study assessed the prognosis, defined as surgery-free survival, in patients with primary infliximab treatment failure as compared to patients without primary failure (initial responders). Furthermore, this study assessed the specter of medical therapies used after primary infliximab treatment failure along with treatment outcomes. METHODS: Retrospective, observational, cohort study of patients with inflammatory bowel disease treated with infliximab as first-line anti-tumor necrosis factor treatment at a tertiary center. Primary infliximab treatment failure was defined as no clinical improvement during infliximab induction therapy resulting in discontinuation of infliximab therapy. RESULTS: A total of 560 patients (Crohn's disease n = 353 and ulcerative colitis n = 207) were treated with infliximab. Among these, 81 (15%) had primary infliximab treatment failure after a median of 3 infusions (weeks 0, 2, and 6) (interquartile range 2-4). The median surgery-free survival was 196 days from first infusion. One year after primary infliximab treatment failure, the majority of patients (n = 51, 63%) had inflammatory bowel disease-related surgery (Crohn's disease n = 19, 58%; ulcerative colitis n = 32, 67%; P = 0.49). There was a markedly increased risk of surgery in patients with primary infliximab treatment failure as compared to initial responders: odds ratio 6.3 (3.8-10.6), P < 0.0001. Among 30 patients handled by medical therapies, 16 (53%) still had active disease 1 year after primary infliximab treatment failure. CONCLUSIONS: Primary infliximab treatment failure is associated with poor outcome including high risk of surgery or sustained active disease despite medical interventions.

Magnitude of Increased Infliximab Clearance Imposed by Anti-infliximab Antibodies in Crohn's Disease Is Determined by Their Concentration.

Antibodies (Abs) against infliximab (IFX) increase IFX clearance and can result in treatment failure and acute hypersensitivity reactions. However, interpretation of their clinical value is complicated by individual differences in Ab responses and methods used for quantification. The increase in IFX clearance imposed by anti-IFX Abs has generally been evaluated using a binary classification, i.e., positive or negative. This analysis aimed to investigate if anti-IFX Ab concentrations provide a more adequate prediction of alterations in clearance. Data originated from a clinical trial on Crohn's disease patients with IFX treatment failure. The trial was not originally designed for pharmacokinetic analysis. Therefore, published pharmacokinetic models were utilized as priors to enable covariate investigation. The impact of anti-IFX Abs on clearance was assessed using different mathematical relationships and exploiting information from two different quantification assays, measuring semi-quantitative "total" or "unbound neutralizing" concentrations of anti-IFX Ab, respectively. Inclusion of anti-IFX Ab status/concentration improved the model's performance for all investigated relationships. The anti-IFX Ab concentrations were superior to the binary classifications, indicating that the magnitude of increase in IFX clearance imposed by anti-IFX Abs closely relates to their concentration. Furthermore, total anti-IFX Ab concentrations appeared superior to the unbound neutralizing fraction in identifying high clearance individuals. Simulations showed that even at low concentrations, anti-IFX Abs lead to sub-therapeutic IFX concentrations, supporting a need of treatment interventions in all anti-IFX Ab positive patients. The developed model can serve as a basis for further investigations to refine treatment recommendations for patients with anti-IFX Abs.

Time Course and Clinical Implications of Development of Antibodies Against Adalimumab in Patients With Inflammatory Bowel Disease.

BACKGROUND: Antibodies (Abs) against adalimumab (ADL) have been associated with low ADL levels and treatment failure. AIM: To characterize the temporal characteristics of anti-ADL Ab appearance and possible disappearance, and determine the clinical significance on drug efficacy and disease course. METHODS: Cohort study including inflammatory bowel disease patients in whom anti-ADL Abs had been assessed by radioimmunoassay (RIA) and, in case of disappearance, by enzyme immunoassay, and functional reporter gene assay. RESULTS: Anti-ADL Abs were evaluated in 133 serum samples from 72 patients. Seventeen patients (24%) tested positive after median of 194 days, interquartile range of 66 to 361. The proportion with anti-ADL Abs was 22% after 1 year, and 32% from 21 months onwards. Anti-ADL Abs generally persisted at repeat assessments during continued ADL therapy (n=8). Disappearance of anti-ADL Abs during therapy (n=3) was presumably caused by methodological biases due to detection of nonfunctional nonpersistent anti-ADL Abs by RIA, or false-negative measurement at reassessment by RIA and reporter gene assay. Anti-ADL Abs appeared pharmacologically active as judged by a median ADL concentration below limit of detection versus 7.4 µg/mL in anti-ADL Ab-negative samples (P<0.0001). Anti-ADL Abs associated with loss of response (odds ratio estimated 67, P<0.0001), and shorter treatment duration (P<0.0001). CONCLUSIONS: Abs against ADL appear in approximately one fourth of inflammatory bowel disease patients with decreasing frequency over time and usually within 1 year of therapy. Anti-ADL Abs generally persist during continued ADL therapy, and are associated with elimination of drug and treatment failure. Therefore, ADL cessation should be considered when anti-ADL Abs are detected and supported by clinical observations.

Immunosuppressive drugs impairs antibody response of the polysaccharide and conjugated pneumococcal vaccines in patients with Crohn's disease.

BACKGROUND: Patients with Crohn's disease (CD) have a higher risk of infectious diseases including pneumococcal infections, and the risk increases with immunotherapy. The primary endpoint of this study was to investigate the specific antibody response to two pneumococcal vaccines in CD patients with and without immunosuppressive treatment four weeks post vaccination. METHODS: In a randomized trial of the 23-valent pneumococcal polysaccharide vaccine (PPV23) and the 13-valent pneumococcal conjugated vaccine (PCV13), a group of CD patients treated with immunosuppressive drugs (IS) alone or in combination with TNF-α antagonists were compared to a group of CD patients not treated with any of these drugs (untreated). Specific pneumococcal antibody concentrations were measured against 12 serotypes common to the two vaccines before and 4 week after vaccination. RESULTS: PCV13 induced a significantly higher antibody response for one serotype (23F) in IS treated patients and for two serotypes (9V and 23F) in untreated patients compared to CD patients vaccinated with PPV23. Untreated PPV23 recipients had higher responses for serotypes 9V and 18C compared to IS+TNF-α treated PPV23 recipients. Comparison between treatment groups showed that immunosuppressive treatment impaired the antibody response to both vaccines and that TNF-a treatment further conveyed additional impairment of the response. CONCLUSION: PCV13 induces higher antibody response for some serotypes compared to PPV23. In addition, CD patients treated with immunosuppressive drugs alone or in combination with TNF-α antagonists had an impaired antibody response to both PPV23 and PCV13 compared to patients not receiving any of these treatments. The study has been registered in the European Clinical Trials Database (EudraCT, record no 2012-002867-86) and ClinicalTrials.gov (record no. NCT01947010).

Implications of Infliximab Treatment Failure and Influence of Personalized Treatment on Patient-reported Health-related Quality of Life and Productivity Outcomes in Crohn's Disease.

BACKGROUND: This study assessed the effects of infliximab (IFX) treatment failure on patient-reported outcomes and explored the influence of using personalized treatment in this situation. METHODS: Sixty-nine Crohn's disease patients with IFX treatment failure were randomized to an intensified IFX regimen (n = 36) or personalized treatment defined by IFX and anti-IFX antibodies (n = 33). Health-related quality of life evaluated with the Short Inflammatory Bowel Disease Questionnaire (IBDQ) and productivity evaluated with the Work Productivity and Activity Impairment Questionnaire (WPAI:CD) were assessed at treatment failure and after 4, 8, 12 and 20 weeks. RESULTS: Median IBDQ score at manifestation of IFX treatment failure was 40 and improved markedly in responders by 11 at weeks 4 and 8 (p < 0.001) and by 13 at weeks 12 and 20 (p < 0.001). Non-responders improved modestly at weeks 12 and 20 (increase of median 4, p < 0.05). Overall activity impairment was high at IFX failure (median 70%) and decreased substantially in responders (40-50%, p < 0.001) and to a lesser extent in non-responders (15-40%, p < 0.05). In employed patients (55%), absenteeism was negligible during the entire study period. However, median presenteeism was 40% at manifestation of IFX failure and decreased only among responders across time (decrease 10-30%, p < 0.05). Although anti-tumour necrosis factor (TNF) therapy was discontinued in most patients handled by personalized treatment, IBDQ and WPAI:CD scores were similar in these patients compared with patients routinely dose-intensified on IFX. CONCLUSION: Regaining low disease activity after IFX failure is necessary for minimizing patient impairment and indirect disease-related costs. A personalized treatment strategy does not have a negative influence on patient-reported outcomes.

Systematic Information to Health-Care Professionals about Vaccination Guidelines Improves Adherence in Patients With Inflammatory Bowel Disease in Anti-TNFα Therapy.

OBJECTIVES: Implementation of guidelines for prevention of infectious diseases during anti-TNFα therapy in patients with inflammatory bowel disease (IBD) is important but difficult. We investigated whether systematic information to health-care professionals about these guidelines improves patients' adherence. METHODS: The study comprised three parts: (1) cross-sectional evaluation of baseline vaccination status in all IBD patients in anti-TNFα therapy (reference group; n=130); (2) prospective interventional study, where health-care professionals received systematic oral and written information about vaccination guidelines at baseline and at 2-month intervals for 6 months, followed by reassessment of vaccination status (intervention group; n=99); (3) cross-sectional evaluation of representative gastroenterologists' knowledge of guidelines (n=53). Outcomes were assessed by validated questionnaires. RESULTS: Patients' adherence to vaccination guidelines increased significantly after a period of systematic information to health-care professionals. Hence, complete adherence increased from 5 to 26%, partial adherence from 38 to 56%, and complete non-adherence decreased from 57 to 18% (P<0.0001). Adherence to all individual vaccinations except human papilloma virus increased significantly (P≤0.0021). Improvement was independent of disease type and anti-TNFα agent. At baseline, only 8% of physicians could identify all elements in the reference guideline. Additional barriers reported by physicians were forgetfulness (32%) and insufficient consultation time (26%). Patient-perceived barriers were costs of vaccinations (35%) and forgetfulness (25%). CONCLUSIONS: Gastroenterologists' limited knowledge of vaccination guidelines during anti-TNFα therapy can be overcome by systematic education of health-care professionals. This inexpensive and easily accessible intervention immediately results in markedly improved patient adherence. Remaining obstacles for adherence comprise high vaccination costs and forgetfulness.

Individualized Therapy Is a Long-Term Cost-Effective Method Compared to Dose Intensification in Crohn's Disease Patients Failing Infliximab.

BACKGROUND: In Crohn's disease patients failing infliximab therapy, interventions defined by an algorithm based on infliximab and anti-infliximab antibody measurements have proven more cost-effective than intensifying the infliximab regimen. AIM: This study investigated long-term economic outcomes at the week 20 follow-up study visit and after 1 year. Clinical outcomes were assessed at week 20. METHODS: Follow-up from a 12-week, single-blind, clinical trial where patients with infliximab treatment failure were randomized to infliximab intensification (5 mg/kg every 4 weeks) (n = 36), or algorithm-defined interventions (n = 33). Accumulated costs, expressed as mean costs per patient, were based on the Danish National Patient Registry. RESULTS: At the scheduled week 20 follow-up study visit, response and remission rates were similar in all study subpopulations between patients treated by the algorithm or by infliximab intensification. However, the sum of healthcare costs related to Crohn's disease was substantially lower (31 %) for patients randomized to algorithm-based interventions than infliximab intensification in the intention-to-treat population: $11,940 versus $17,236; p = 0.005. For per-protocol patients (n = 55), costs at the week 20 follow-up visit were even lower (49 %) in the algorithm group: $8,742 versus $17,236; p = 0.002. Figures were similar for patients having completed the 12-week trial as per protocol (50 % reduction in costs) (n = 45). Among patients continuing the allocated study intervention throughout the entire 20-week follow-up period (n = 29), costs were reduced by 60 % in algorithm-treated patients: $7,056 versus $17,776; p < 0.001. Cost-reduction percentages remained stable throughout one year. CONCLUSION: Economic benefit of algorithm-based interventions at infliximab failure is maintained throughout 1 year.

Colonoscopy surveillance for dysplasia and colorectal cancer in patients with inflammatory bowel disease.

The risk of colorectal cancer (CRC) and dysplasia in patients with inflammatory bowel disease (IBD) has been highly debated as risk estimates from different studies vary greatly. The present national Danish guideline on colonoscopy surveillance for dysplasia and colorectal cancer in patients with IBD is based on a thorough review of existing literature with particular focus on recent studies from Denmark revealing a lower risk of CRC than previously assumed. The overall risk of CRC in the Danish IBD population does not appear to be different from that of the background population; however, in some subgroups of patients the risk is increased. These subgroups of patients, who should be offered colonoscopy surveillance, include patients with ulcerative colitis having extensive disease and a long disease duration (10-13 years); early age at onset (less than 19 years of age) of ulcerative colitis; and patients with ulcerative colitis as well as Crohn's disease with a concomitant diagnosis of primary sclerosing cholangitis. A colonoscopy surveillance program is recommended in these subgroups with intervals ranging from every 3-6 months to every 5 years, using chromoendoscopy with targeted biopsies of the lesion and adjacent mucosa, instead of conventional colonoscopy with random biopsies. Preferably, the colonoscopy should be performed during clinical remission. If a lesion is detected the endoscopical resectability together with the pathology of the lesion and the adjacent mucosa determine how the lesion should be treated.

Changes in serum trough levels of infliximab during treatment intensification but not in anti-infliximab antibody detection are associated with clinical outcomes after therapeutic failure in Crohn's disease.

BACKGROUND AND AIMS: Intensification of the infliximab (IFX) regimen is recommended if the treatment effect is inadequate. However, the rationale for this is not well defined as the underlying mechanisms vary. The aim of this study was to explore the association between changes in serum IFX and anti-IFX antibodies (Abs) after IFX intensification and clinical outcomes. METHODS: We performed a post hoc analysis of a randomized clinical trial including 42 Crohn's disease patients with IFX treatment failure, all treated with an intensified IFX regimen (5mg/kg every 4 week) for 12 weeks. Trough serum IFX and anti-IFX Ab concentrations were measured by a homogeneous mobility shift binding assay (HMSA) and a functional cell-based reporter gene assay (RGA) at treatment failure and the end of the trial. RESULTS: Twenty-one patients (50%) regained clinical response on the intensified IFX regimen. The increase in serum trough levels of IFX during treatment intensification was higher among responders than non-responders (RGA, 8.8 versus 3.0 µg/mL, p = 0.035; HMSA, 9.9 versus 4.7 µg/mL, p = 0.040), and differentiated patients by clinical outcome (RGA, area under receiver operating characteristic curve [AUC] 0.75 [0.53-0.97], p = 0.035; HMSA, AUC 0.74 [0.53-0.95], p = 0.042). All responders exhibited an IFX increase ≥2.6 µg/mL (sensitivity 100%, specificity 50%). Anti-IFX Abs detected by HMSA in 13 patients (32%) were often non-functional and became undetectable during IFX intensification. However, even functional anti-IFX Abs detected by RGA in six patients (15%) became undetectable. CONCLUSION: Increase in IFX levels following treatment intensification was associated with improved clinical outcomes, indicating insufficient drug levels in a subgroup of patients. Anti-IFX Abs may become undetectable during treatment intensification, suggesting lowered production or the formation of immune complexes.

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.

Clinical implications of measuring drug and anti-drug antibodies by different assays when optimizing infliximab treatment failure in Crohn's disease: post hoc analysis of a randomized controlled trial.

OBJECTIVES: Cost-effective guidance of therapeutic strategy in Crohn's disease patients with secondary infliximab (IFX) treatment failure may be achieved by serum IFX and anti-IFX antibody (Ab) measurements by radioimmunoassay (RIA). This study investigated implications of using other techniques for this purpose. METHODS: This is a post hoc analysis of randomized clinical trial including 66 Crohn's disease patients with IFX failure in whom IFX and anti-IFX Ab measurements by RIA had been used for therapeutic guidance. Samples were additionally assessed by enzyme-linked immunosorbent assay (ELISA), homogeneous mobility shift assay (HMSA), and functional cell-based reporter gene assay (RGA). RESULTS: IFX detection was comparable between assays (82% RIA, 76% ELISA, 88% HMSA, and 74% RGA), and it correlated significantly (Pearson's r=0.91-0.97, P<0.0001). However, IFX concentrations varied systematically between all pair of assays except RIA-RGA. Anti-IFX Ab detection was variable (27% RIA, 9% ELISA, 33% HMSA, and 11% RGA), but correlated significantly (Pearson's r=0.77-0.96; P<0.0001). Anti-IFX Abs detected by RIA and HMSA were often from sera without drug-neutralizing activity (RGA). Assays agreed on classification of underlying mechanism for treatment failure in most cases (79-94%). The majority (74-88%) failed IFX owing to pharmacodynamic problems, or had noninflammatory pathophysiology for symptoms resembling relapse. Applied threshold for therapeutic vs. subtherapeutic IFX level influenced classifications. The four different assays did not differ in terms of the ability to predict response to interventions defined by the algorithm. CONCLUSIONS: Despite variable analytical properties, common assays result in similar classifications and interventions in patients with IFX treatment failure, and with comparable clinical outcomes. Implications are, however, profound for the minority classified differently.

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.

Electrostatic discharges and their effect on the validity of registered values in intracranial pressure monitors.

OBJECT: Intracranial pressure (ICP) monitoring is used extensively in clinical practice, and as such, the accuracy of registered ICP values is paramount. Clinical observations of nonphysiological changes in ICP have called into question the accuracy of registered ICP values. Subsequently, the authors have tried to determine if the ICP monitors from major manufacturers were affected by electrostatic discharges (ESDs), if the changes were permanent or transient in nature, and if the changes were modified by the addition of different electrical appliances normally used in the neurointensive care unit environment. METHODS: The authors established a test setup in the neurointensive care unit using a large container filled with isotonic saline, creating a phantom patient. Intracranial pressure monitors were sequentially lowered into the container and subjected to a predefined test battery of ESDs. RESULTS: Five pressure monitors from 4 manufacturers were evaluated. Three monitors containing electrical circuitry at the tip of the transducer were all affected by ESDs. Clinically significant permanent changes in the reported ICP values for 1 pressure monitor were observed, as well as temporary deflections for 2 other monitors. The monitors had different levels of sensitivity to discharges at low voltages. CONCLUSIONS: These results explain some of the sudden shifts in ICP noted in the clinical setting. However, a clear deflection pattern related to the addition of electrical appliances was not found. The authors recommend instituting policies for reducing the risk of subjecting patients to ESDs in the neurointensive care unit setting.

Comparison of techniques for monitoring infliximab and antibodies against infliximab in Crohn's disease.

BACKGROUND: Several techniques are used to measure infliximab (IFX) and anti-IFX antibodies (Abs) in Crohn's disease. The aim of this study was to compare different assays for this purpose. METHODS: Fluid-phase radioimmunoassay (RIA), solid-phase enzyme-linked immunosorbent assay (ELISA), reporter gene assay (RGA), and enzyme immunoassay (EIA; anti-IFX Ab only) were assessed. IFX was added to pooled serum from 13 patients with inactive Crohn's disease to yield concentrations of 0, 1, 3, and 9 µg/mL. Anti-IFX Abs were assessed in 6 patients. RESULTS: IFX assessments: RIA and RGA had lower limit of detection than ELISA (0.07 µg/mL and 0.13 versus 0.26). Maximal inaccuracies were 39%, 24%, and 23%. Imprecisions (coefficients of variation) were ≤20% within IFX concentrations between 1 and 9 µg/mL. All assays showed linear correlations (R = 0.97-0.99), but sample concentrations differed by up to 1.55 µg/mL for RIA and RGA, 1.41 µg/mL for ELISA and RIA, and 0.48 µg/mL for ELISA and RGA (P < 0.05). Anti-IFX Ab assessments: RGA gave highly reproducible results (coefficients of variation ≤ 7%) compared with all others (24%-26%). All assays had linear correlations (R = 0.71-0.93), except ELISA versus RGA and EIA. Assays disagreed on anti-IFX Ab titers with mean difference -420 (-1200 to 210) in RGA and EIA, and up to 4500 (-2700 to 11,800) in RIA and RGA. A contributing factor to these discrepancies was inability of ELISA to detect IgG4 anti-IFX Abs. CONCLUSIONS: Performances of assays for IFX and anti-IFX Abs are comparable. However, IFX concentrations and anti-IFX Ab titers show systematic differences, and in individual patients, only the same assay should be used. Problems may arise when different assays are used to manage therapies in the same patient.

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.