References of "Van Steen, Kristel"
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See detailPancreatic autoantibodies in inflammatory bowel disease
Joossens, S.; Vermeire, S.; Van Steen, Kristel ULg et al

in Inflammatory Bowel Diseases (2004), 10(6), 771-777

Background: Autoantibodies against exocrine pancreas (PABs) have been reported to be specific for Crohn's disease (CD), albeit at a low prevalence (30%). We studied PABs in patients with inflammatory ... [more ▼]

Background: Autoantibodies against exocrine pancreas (PABs) have been reported to be specific for Crohn's disease (CD), albeit at a low prevalence (30%). We studied PABs in patients with inflammatory bowel disease (IBD), unaffected family members, and control subjects. Methods: A Belgian study cohort of 575 subjects, including 289 IBD patients (CD, 169 patients; ulcerative colitis [UC], 120 patients), 108 unaffected first-degree relatives, 78 subjects with non-IBD gastrointestinal disorders (gastrointestinal control subjects [GIcos]), and 100 healthy control subjects (Hcos), were tested for PAB by a standardized indirect immunofluorescence method. Results: The prevalence of PABs in this study cohort was 32% for CD, 23.3% for UC, and 22.2% for their unaffected family members (all P < 0.001), compared with 1.3% for GIcos and 0% for Hcos. Two staining patterns could be observed: an intracellular pattern (IC); and an extracellular pattern (EC). The EC was significantly more prevalent in CD patients compared with UC patients (P = 0.014), and higher titers of this pattern were found in CD patients (P = 0.01). Both PAB patterns were negatively associated with stricturing disease behavior of CD (P = 0.021). The IC was associated with familial CD (P = 0.0009) and familial UC (P = 0.0003). Conclusions: The prevalence of PAB found in CD patients in this study was similar to that cited in previous reports. In contrast to these reports, we also found an increased prevalence of PABs in patients with UC and in unaffected first-degree relatives of IBD patients. We observed two main staining patterns, both of which were present in IBD and were associated with specific phenotypes of the disease. [less ▲]

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See detailTumour necrosis factor- receptor 1 and 2 polymorhpisms in inflammatory bowel disease and their association with response to infliximab
Pierik, M.; Vermeire, S.; Van Steen, Kristel ULg et al

in Alimentary Pharmacology & Therapeutics (2004), 20

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See detailHealth-related quality of life parameters as prognostic factors in a nonmetastatic breast cancer population: An international multicenter study
Efficace, F.; Therasse, P.; Piccart, M. J. et al

in Journal of Clinical Oncology (2004), 22(16), 3381-3388

Purpose The purpose of this research was to evaluate whether baseline health-related quality of life (HRQOL) parameters are prognostic factors for survival in locally advanced breast cancer patients ... [more ▼]

Purpose The purpose of this research was to evaluate whether baseline health-related quality of life (HRQOL) parameters are prognostic factors for survival in locally advanced breast cancer patients. Although the literature highlights the important role of HRQOL parameters in predicting survival in advanced metastatic disease, little evidence exists for earlier stages. Patients and Methods The overall sample consisted of 448 patients randomly assigned to receive cyclophosphamide, epirubicin, and fluorouracil versus epirubicin, cyclophosphamide, and granulocyte colony-stimulating factor. Patients were enrolled in 12 countries. HRQOL baseline scores were assessed using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire C30. The Cox proportional hazards regression model was used for both univariate and multivariate analyses of survival. In addition, a bootstrap resampling technique was used to assess the stability of the outcomes. Bootstrap results were then applied for model averaging purposes as a means to account for the observed model selection uncertainty. Results The final multivariate model retained inflammatory breast cancer (T4d) as the only factor predicting overall survival (OS) with a hazard ratio of 1.375 (95% CI, 1.027 to 1.840; P = .03). The presence of inflammatory breast cancer lowers the median survival time from 6.6 to 4.2 years (36% reduction). None of the preselected HRQOL variables were prognostic for OS or disease-free survival, in either the univariate or multivariate analysis. Conclusion Our findings suggest that baseline HBQOL parameters have no prognostic value in a nonmetastatic breast cancer population. [less ▲]

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See detailGenome wide scan in a Flemish inflammatory bowel disease population: support for the IBD4 locus, population heterogeneity, and epistasis
Vermeire, S.; Rutgeerts, P.; Van Steen, Kristel ULg et al

in Gut (2004), 53(7), 980-986

Background and aims: Genome wide scans in inflammatory bowel disease (IBD) have indicated various susceptibility regions with replication of 16cen (IBD1), 12q (IBD2), 6p (IBD3), 14q11 (IBD4), and 3p21. As ... [more ▼]

Background and aims: Genome wide scans in inflammatory bowel disease (IBD) have indicated various susceptibility regions with replication of 16cen (IBD1), 12q (IBD2), 6p (IBD3), 14q11 (IBD4), and 3p21. As no linkage was previously found on IBD regions 3, 7, 12, and 16 in Flemish IBD families, a genome wide scan was performed to detect other susceptibility regions in this population. Methods: A cohort of 149 IBD affected relative pairs, all recruited from the Northern Flemish part of Belgium, were genotyped using microsatellite markers at 12 cM intervals, and analysed by Genehunter non-parametric linkage software. All families were further genotyped for the three main Crohn's disease associated variants in the NOD2/CARD15 gene. Results: Nominal evidence for linkage was observed on chromosomes 1 (D1S197: multipoint nonparametric linkage (NPL) score 2.57, p = 0.004; and at D1S305-D1S252: NPL 2.97, p = 0.001), 4q (D4S406: NPL 1.95, p = 0.03), 6q16 (D6S314: NPL 2.44, p = 0.007), 10p12 (D10S197: NPL 2.05, p = 0.02), 11q22 (D11S35-D11S927: NPL 1.95, p = 0.02) 14q11-12 (D14S80: NPL 2.41, p = 0.008), 20p12 (D20S192: NPL 2.7, p = 0.003), and Xq (DXS990: NPL 1.70, p = 0.04). A total of 51.4% of patients carried at least one NOD2/CARD15 variant. Furthermore, epistasis was observed between susceptibility regions 6q/10p and 20p/10p. Conclusion: Genome scanning in a Flemish IBD population found nominal evidence for linkage on 1p, 4q, 10p12, and 14q11, overlapping with other genome scan results, with linkage on 14q11-12 supporting the IBD4 locus. The results further show that epistasis is contributing to the complex model of IBD and indicate that population heterogeneity is not to be underestimated. Finally, NOD2/CARD15 is clearly implicated in the Flemish IBD population. [less ▲]

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See detailMulticollinearity
Van Steen, Kristel ULg; Molenberghs, G.

in Chow, Shein-Chung (Ed.) Encyclopedia of Biopharmaceutical Statistics (2004)

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See detailA family-based association test for repeatedly measured quantitative traits adjusting for unknown environmental and/or polygenic effects
Lange, C.; Van Steen, Kristel ULg; Andrew, T. et al

in Statistical Applications in Genetics and Molecular Biology (2004), 3(1), 17

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See detailDeficient host-bacteria interactions in inflammatory bowel disease? The toll-like receptor (TLR)-4 Asp299gly polymorphism is associated with Crohn's disease and ulcerative colitis
Franchimont, D.; Vermeire, S.; El Housni, H. et al

in Gut (2004), 53(7), 987-992

Background and aims: Elicitation of an innate immune response to bacterial products is mediated through pattern recognition receptors (PRRs) such as the toll-like receptors (TLRs) and the NODs. The ... [more ▼]

Background and aims: Elicitation of an innate immune response to bacterial products is mediated through pattern recognition receptors (PRRs) such as the toll-like receptors (TLRs) and the NODs. The recently characterised Asp299Gly polymorphism in the lipopolysaccharide (LPS) receptor TLR4 is associated with impaired LPS signalling and increased susceptibility to Gram negative infections. We sought to determine whether this polymorphism was associated with Crohn's disease ( CD) and/or ulcerative colitis (UC). Methods: Allele frequencies of the TLR4 Asp299Gly polymorphism and the three NOD2/CARD15 polymorphisms (Arg702Trp, Gly908Arg, and Leu1007fsinsC) were assessed in two independent cohorts of CD patients ( cohort 1, n = 334; cohort 2, n = 114), in 163 UC patients, and in 140 controls. A transmission disequilibrium test (TDT) was then performed on 318 inflammatory bowel disease (IBD) trios. Results: The allele frequency of the TLR4 Asp299Gly polymorphism was significantly higher in CD ( cohort 1: 11% v 5%, odds ratio ( OR) 2.31 (95% confidence interval (CI) 1.28 - 4.17), p = 0.004; and cohort 2: 12% v 5%, OR 2.45 ( 95% CI 1.24 - 4.81), p = 0.007) and UC patients (10% v 5%, OR 2.05 ( 95% CI 1.07 3.93), p = 0.027) compared with the control population. A TDT on 318 IBD trios demonstrated preferential transmission of the TLR4 Asp299Gly polymorphism from heterozygous parents to affected children (T/U: 68/34, p = 0.01). Carrying polymorphisms in both TLR4 and NOD2 was associated with a genotype relative risk (RR) of 4.7 compared with a RR of 2.6 and 2.5 for TLR4 and NOD2 variants separately. Conclusion: We have reported on a novel association of the TLR4 Asp299Gly polymorphism with both CD and UC. This finding further supports the genetic influence of PRRs in triggering IBD. [less ▲]

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See detailTransmission of CARD15 (NOD2) variants within families of patients with inflammatory bowel disease.
Esters, Nele; Pierik, Marie; Van Steen, Kristel ULg et al

in American Journal of Gastroenterology (2004), 99(2), 299-305

OBJECTIVES: Three single nucleotide polymorphisms (SNPs) in CARD15 have been independently associated with Crohn's disease (CD). Since nothing is known about the transmission of these variants within ... [more ▼]

OBJECTIVES: Three single nucleotide polymorphisms (SNPs) in CARD15 have been independently associated with Crohn's disease (CD). Since nothing is known about the transmission of these variants within families, this was the subject of our study in Flemish patients with inflammatory bowel disease (IBD) and their healthy relatives. METHODS: A cohort of 1,670 individuals (570 CD, 173 UC, 165 healthy controls, 762 first-degree unaffected relatives of CD patients) was genotyped for Arg702Trp, Gly908Arg, and Leu1007fsinsC. Mutant allele and carrier frequencies were compared between groups. Segregation patterns were compared using a bivariate Dale model. RESULTS: The carrier prevalence of CARD15 variants for CD patients was 46.3%, compared to 20.6% for healthy controls and 22.0% for ulcerative colitis (UC) patients (both p < 0.0001). An increased carriage rate of CARD15 variants was observed in unaffected relatives of CD patients (37.3%; p < 0.0001 vs controls), although this was significantly lower than in the CD patients (p = 0.001). Paternal transmission gave a 5.17-fold higher chance for the child to develop the disease compared to maternal transmission (95% CI [1.59, 16.78]; p = 0.0063). UC patients belonging to mixed IBD families carried significantly more mutations (42.3%) compared to other UC patients (18.4%) (p < 0.01). CONCLUSIONS: Maternal transmission of the CARD15 variant allele is associated with a lower proportion of affected individuals compared to paternal transmission. Therefore, maternal transmission does not carry an increased risk of transmission as does paternal transmission. The increased mutation carriage in unaffected siblings of CD patients and in UC patients belonging to mixed families suggests that other factors than CARD15 contribute to the eventual disease expression. [less ▲]

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See detailInterassay and interobserver variability in the detection of anti-neutrophil cytoplasmic antibodies in patients with ulcerative colitis.
Joossens, Sofie; Daperno, Marco; Shums, Zakera et al

in Clinical Chemistry (2004), 50(8), 1422-5

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See detailGenomic screening in family-based association testing
Van Steen, Kristel ULg; McQueen, M.; Herbert, A. et al

in Genetic Epidemiology (2004), 27

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See detailAutoimmunity associated with anti-tumor necrosis factor alpha treatment in Crohn's disease: A prospective cohort study
Vermeire, S.; Noman, M.; Van Assche, G. et al

in Gastroenterology (2003), 125(1), 32-39

Background & Aims: Infliximab therapy is an effective approach to treating Crohn's disease. Development of antinuclear antibodies has been described in patients treated, but the size of the problem and ... [more ▼]

Background & Aims: Infliximab therapy is an effective approach to treating Crohn's disease. Development of antinuclear antibodies has been described in patients treated, but the size of the problem and the relationship with autoimmunity have not been investigated. We investigated the occurrence of antinuclear antibodies in 125 consecutive Crohn's disease patients and studied the relationship with symptoms of autoimmunity. Methods: Autoantibodies and clinical data were investigated before and 1, 2, and 3 months after infliximab infusion. If antinuclear antibodies were greater than or equal to1:80, further study of double-stranded DNA, single-stranded DNA, histones, and ENA was performed. Results: Cumulative antinuclear antibody incidence at 24 months was 71 of 125 (56.8%). Almost half of these patients developed antinuclear antibodies after the first infusion, and >75% became antinuclear antibody positive after fewer than 3 infusions. So far, only :15 of 71 patients have become seronegative, after a median of 12 months. Of 43 antinuclear antibody-positive patients who were further subtyped, 14 of 43 (32.6%) had double-stranded DNA, 17 (39.5%) had single-stranded DNA, 9 (20.9%) had antihistone, and 0% were ENA positive. Two patients (both antihistone and double-stranded DNA positive) developed drug-induced lupus without major organ damage, and I developed autoimmune hemolytic anemia. Antinuclear antibodies were associated with the female sex (odds ratio, 3.166; 95% confidence interval, 1.167-8.585; P = 0.024) and with papulosquamous or butterfly rash (odds ratio, 10.016; 95% confidence interval, 1.708-58.725; P = 0.011). Conclusions: The cumulative incidence of antinuclear antibodies was 56.8% after 24 months in this cohort of infliximab-treated Crohn's disease patients. Antinuclear antibodies persisted up to I year after the last infusion, and only a few patients became seronegative. Two patients developed drug-induced lupus erythematosus. Antinuclear antibodies were associated with the female sex and skin manifestations. [less ▲]

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See detailThe value of serologic markers in indeterminate colitis: A prospective follow-up study - Reply
Joossens, S.; Van Steen, Kristel ULg; Vermeire, S. V. et al

in Gastroenterology (2003), 125(3), 999-1000

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See detailA local influence approach applied to binary data from a psychiatric study.
Jansen, Ivy; Molenberghs, Geert; Aerts, Marc et al

in Biometrics (2003), 59(2), 410-9

Recently, a lot of concern has been raised about assumptions needed in order to fit statistical models to incomplete multivariate and longitudinal data. In response, research efforts are being devoted to ... [more ▼]

Recently, a lot of concern has been raised about assumptions needed in order to fit statistical models to incomplete multivariate and longitudinal data. In response, research efforts are being devoted to the development of tools that assess the sensitivity of such models to often strong but always, at least in part, unverifiable assumptions. Many efforts have been devoted to longitudinal data, primarily in the selection model context, although some researchers have expressed interest in the pattern-mixture setting as well. A promising tool, proposed by Verbeke et al. (2001, Biometrics 57, 43-50), is based on local influence (Cook, 1986, Journal of the Royal Statistical Society, Series B 48, 133-169). These authors considered the Diggle and Kenward (1994, Applied Statistics 43, 49-93) model, which is based on a selection model, integrating a linear mixed model for continuous outcomes with logistic regression for dropout. In this article, we show that a similar idea can be developed for multivariate and longitudinal binary data, subject to nonmonotone missingness. We focus on the model proposed by Baker, Rosenberger, and DerSimonian (1992, Statistics in Medicine 11, 643-657). The original model is first extended to allow for (possibly continuous) covariates, whereafter a local influence strategy is developed to support the model-building process. The model is able to deal with nonmonotone missingness but has some limitations as well, stemming from the conditional nature of the model parameters. Some analytical insight is provided into the behavior of the local influence graphs. [less ▲]

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See detailGuidelines for the use of epoetin: have quality-of-life benefits been proven?
Bottomley, Andrew; Thomas, Ronald; Van Steen, Kristel ULg et al

in Journal of Clinical Oncology (2003), 21(11), 22232224-5

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See detailMultivariate and multidimensional analysis
Van Steen, Kristel ULg; Molenberghs, G.

in Wilson (Ed.) Biometrics (2003)

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See detailTransmission of CARD15 (NOD2) variants in families with Crohns disease
Vermeire, S.; Esters, N.; Pierik, M. et al

in Gastroenterology (2003), 124(4 (Suppl I)), 368

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See detailThe multivariate Dale model and genetic associations
Van Steen, Kristel ULg; Molenberghs, G.; Tahri, N.

in American Journal of Human Genetics (2002), 71

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See detailMulticollinearity in prognostic factor analyses using the EORTC QLQ-C30: identification and impact on model selection
Van Steen, Kristel ULg; Curran, D.; Kramer, J. et al

in Statistics in Medicine (2002), 21(24), 3865-3884

Clinical and quality of life (QL) variables from an EORTC clinical trial of first line chemotherapy in advanced breast cancer were used in a prognostic factor analysis of survival and response to ... [more ▼]

Clinical and quality of life (QL) variables from an EORTC clinical trial of first line chemotherapy in advanced breast cancer were used in a prognostic factor analysis of survival and response to chemotherapy. For response, different final multivariate models were obtained from forward and backward selection methods, suggesting a disconcerting instability. Quality of life was measured using the EORTC QLQ-C30 questionnaire completed by patients. Subscales on the questionnaire are known to be highly correlated, and therefore it was hypothesized that multicollinearity contributed to model instability. A correlation matrix indicated that global QL was highly correlated with 7 out of 11 variables. In a first attempt to explore multicollinearity, we used global QL as dependent variable in a regression model with other QL subscales as predictors. Afterwards, standard diagnostic tests for multicollinearity were performed. An exploratory principal components analysis and factor analysis of the QL subscales identified at most three important components and indicated that inclusion of global QL made minimal difference to the loadings on each component. suggesting that it is redundant in the model, In a second approach, we advocate a bootstrap technique to assess the stability of the models. Based on these analyses and since global QL exacerbates problems of multicollinearity, we therefore recommend that global QL be excluded from prognostic factor analyses using the QLQ-C30. The prognostic factor analysis was rerun without global QL in the model, and selected the same significant prognostic factors as before. Copyright (C) 2002 John Wiley Sons, Ltd. [less ▲]

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See detailMerits of the multivariate Dale model in genetic association studies
Van Steen, Kristel ULg; Molenberghs, G.; Tahri, N.

in Genetic Epidemiology (2002), 23

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See detailErythropoietin improves quality of life--a response.
Bottomley, Andrew; Thomas, Ronald; Van Steen, Kristel ULg et al

in Lancet Oncology (2002), 3(9), 527

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