The effect of the Flemish breast cancer screening program on breast cancer-specific mortality: A case-referent study.

BACKGROUND: Breast cancer screening programs were introduced in many countries worldwide following randomized controlled trials in the 1980s showing a reduction in breast cancer-specific mortality. However, their effectiveness remains debated and estimates vary. A breast cancer screening program was introduced in 2001 in Flanders, Belgium where high levels of opportunistic screening practices are observed. The effectiveness of this program was estimated by measuring its effect on breast cancer-specific mortality. METHODS: We performed a case-referent study to investigate the effect of participation in the Flemish population-based mammography screening program (PMSP) on breast cancer-specific mortality from 2005 to 2017. A multiple logistic regression model assessed the association between breast cancer-specific death and screening program participation status in the four years prior to (pseudo)diagnosis (yes/no), with adjustment for potential confounders (individual socio-economic position and calendar year of diagnosis) and stratified for age. In addition, we performed different sensitivity analyses. RESULTS: We identified 1571 cases and randomly selected 6284 referents. After adjustment, women who participated in PMSP had a 51 % lower risk of breast cancer-specific mortality compared to those who did not (adjusted odds ratio [aOR] =0.49, 95 % CI: 0.44-0.55). Sensitivity analyses did not markedly change the estimated associations. Correction for self-selection bias reduced the effect size, but the estimate remained significant. CONCLUSION: Our results indicate that in a context of high opportunistic screening rates, participation in breast cancer screening program substantially reduces breast cancer-specific mortality. For policy, these results should be balanced against the potential harms of screening, including overdiagnosis and overtreatment.

Antithrombotic medication and endovascular interventions associated with short-term exposure to particulate air pollution: A nationwide case-crossover study.

Short-term exposure to air pollution has pro-thrombotic effects and triggers thrombo-embolic events such as myocardial infarction or stroke in adults. This study evaluates the association between short-term variation in air pollution and treatments for acute thrombo-embolic events among the whole Belgian population. In a bidirectional time-stratified case-crossover design, we included 227,861 events treated with endovascular intervention and 74,942 with antithrombotic enzymes that were reimbursed by the Belgian Social Security between January 1st, 2009 and December 31st, 2013. We compared the concentrations of particulate matter (PM) air pollution (PM10 and PM2.5), as estimated at the municipality level on the day of the event (lag 0) and two days earlier (lag 1 and lag 2) with those of control days from the same month, matched by temperature and accounting for day of the week (weekend vs week days). We applied conditional logistic regression models to obtain odds ratios (OR) and their 95% CI for an increase of 10 µg/m3 (PM10) or 5 µg/m3 (PM2.5) in pollutant concentrations over three lag days (lag 0, 1 and 2). We observed significant associations of PM10 and PM2.5 with treatment of acute thrombo-embolic events at the three lags. The strongest associations were observed for air pollution concentrations on the day of the event (lag0). Increases of 10 µg/m3 PM10 and 5 µg/m3 PM2.5 on lag0 increased the odds of events treated with endovascular intervention by 2.7% (95%CI:2.3%-3.2%) and 1.3% (95%CI:1%-1.5%), respectively, and they increased the odds of events treated with antithrombotic enzymes by 1.9% (95%CI:1.1-2.7%) and 1.2% (95%CI:0.7%-1.6%), respectively. The associations were generally stronger during autumn months and among children. Our nationwide study confirms that acute exposure to outdoor air pollutants such as PM10 or PM2.5 increase the use of medication and interventions to treat thrombo-embolic events.

Mortality in Individuals Treated With Glucose-Lowering Agents: A Large, Controlled Cohort Study.

CONTEXT: Several observational studies and meta-analyses have reported increased mortality of patients taking sulfonylurea and insulin. The impact of patient profiles and concomitant therapies often remains unclear. OBJECTIVE: The objective of the study was to quantify survival of patients after starting glucose-lowering agents (GLAs) and compare it with control subjects, matched for risk profiles and concomitant therapies. DESIGN: This was a retrospective, controlled, cohort study. SETTING: The study is based on health expenditure records of the largest Belgian health mutual insurer, covering more than 4.4 million people. PATIENTS: A total of 115 896 patients starting metformin, sulfonylurea, or insulin (alone or in combination) between January 2003 and December 2007 participated in the study. Control subjects without GLA therapy were matched for age, gender, history of cardiovascular events, and therapy with antihypertensives, statins and blood platelet aggregation inhibitors. INTERVENTION(S): There were no interventions. MAIN OUTCOME MEASURE: Five-year survival after the start of GLA was measured. RESULTS: Profiles of patients using different GLAs varied, with patients on sulfonylurea being oldest and patients on insulin having more frequently a history of cardiovascular disease. Excess mortality differed across GLA therapies compared with matched controls without GLAs, even after adjusting for observable characteristics. Only metformin monotherapy was not associated with an increased 5-year mortality compared with matched controls, whereas individuals on a combination of sulfonylurea and insulin had the highest mortality risks. Age and concomitant use of statins strongly affect survival. CONCLUSIONS: Differences exist in 5-year survival of patients on GLA, at least partly driven by the risk profile of the individuals themselves. Metformin use was associated with lowest 5-year mortality risk and statins dramatically lowered 5-year mortality throughout all cohorts.

The impact of non-financial and financial encouragements on participation in non school-based human papillomavirus vaccination: a retrospective cohort study.

OBJECTIVE: Adolescent vaccination coverage under a system of non school-based vaccination is likely to be suboptimal, but might be increased by targeted encouragement campaigns. We analysed the effect on human papillomavirus (HPV) vaccination initiation by girls aged 12-18 of two campaigns set up in Flanders (Belgium) in 2007 and 2009: a personal information campaign and a combined personal information and financial incentive campaign. METHODS: We analysed (objective) data on HPV vaccination behaviour from the National Alliance of Christian Mutualities (NACM), Flanders' largest sickness fund. We used z-scores to compare the monthly proportion of girls initiating HPV vaccination over time between carefully selected intervention and control groups. Separate analyses were done for older and younger girls. Total sample sizes of the intervention (control) groups were 221 (243) for the personal information campaign and 629 (5,322) for the combined personal information and financial incentive campaign. RESULTS: The personal information campaign significantly increased vaccination initiation, with older girls reacting faster. One year after the campaign the percentages of vaccination initiation for the oldest girls were 64.6 and 42.8 % in the intervention and control group, respectively (z = 3.35, p = 0.0008); for the youngest girls the percentages were 78.4 and 68.1 % (z = 1.71, p = 0.09). The combined personal information and financial incentive campaign increased vaccination initiation among certain age groups. One year after the campaign the difference in percentage points for HPV vaccination initiation between intervention and control groups varied between 18.5 % (z = 3.65, p = 0.0002) and 5.1 % (z = 1.12, p = 0.26). CONCLUSION: Under a non school-based vaccination system, personal information and removing out-of-pocket costs had a significant positive effect on HPV vaccination initiation, although the effect substantially varied in magnitude. Overall, the obtained vaccination rates remained far below those realised under school-based HPV vaccination.

Did Large-Scale Vaccination Drive Changes in the Circulating Rotavirus Population in Belgium?

Vaccination can place selective pressures on viral populations, leading to changes in the distribution of strains as viruses evolve to escape immunity from the vaccine. Vaccine-driven strain replacement is a major concern after nationwide rotavirus vaccine introductions. However, the distribution of the predominant rotavirus genotypes varies from year to year in the absence of vaccination, making it difficult to determine what changes can be attributed to the vaccines. To gain insight in the underlying dynamics driving changes in the rotavirus population, we fitted a hierarchy of mathematical models to national and local genotype-specific hospitalization data from Belgium, where large-scale vaccination was introduced in 2006. We estimated that natural- and vaccine-derived immunity was strongest against completely homotypic strains and weakest against fully heterotypic strains, with an intermediate immunity amongst partially heterotypic strains. The predominance of G2P[4] infections in Belgium after vaccine introduction can be explained by a combination of natural genotype fluctuations and weaker natural and vaccine-induced immunity against infection with strains heterotypic to the vaccine, in the absence of significant variation in strain-specific vaccine effectiveness against disease. However, the incidence of rotavirus gastroenteritis is predicted to remain low despite vaccine-driven changes in the distribution of genotypes.

From non school-based, co-payment to school-based, free Human Papillomavirus vaccination in Flanders (Belgium): a retrospective cohort study describing vaccination coverage, age-specific coverage and socio-economic inequalities.

School-based, free HPV vaccination for girls in the first year of secondary school was introduced in Flanders (Belgium) in 2010. Before that, non school-based, co-payment vaccination for girls aged 12-18 was in place. We compared vaccination coverage, age-specific coverage and socio-economic inequalities in coverage - 3 important parameters contributing to the effectiveness of the vaccination programs - under both vaccination systems. We used retrospective administrative data from different sources. Our sample consisted of all female members of the National Alliance of Christian Mutualities born in 1995, 1996, 1998 or 1999 (N=66,664). For each vaccination system we described the cumulative proportion HPV vaccination initiation and completion over time. We used life table analysis to calculate age-specific rates of HPV vaccination initiation and completion. Analyses were done separately for higher income and low income groups. Under non school-based, co-payment vaccination the proportions HPV vaccination initiation and completion slowly rose over time. By age 17, the proportion HPV vaccination initiation/completion was 0.75 (95% CI 0.74-076)/0.66 (95% CI 0.65-0.67). The median age at vaccination initiation/completion was 14.4 years (95% CI 14.4-14.5)/15.4 years (95% CI 15.3-15.4). Socio-economic inequalities in coverage widened over time and with age. Under school-based, free vaccination rates of HPV vaccination initiation were substantially higher. By age 14,the proportion HPV vaccination initiation/completion was 0.90 (95% CI 0.90-0.90)/0.87 (95% CI 0.87-0.88). The median age at vaccination initiation/completion was 12.7 years (95% CI 12.7-12.7)/13.3 years (95% CI 13.3-13.3). Socio-economic inequalities in coverage and in age-specific coverage were substantially smaller.

The health and economic burden of haemophilia in Belgium: a rare, expensive and challenging disease.

BACKGROUND: Haemophilia is a rare hereditary haemorrhagic disease that requires regular intravenous injections of clotting factor (CF) concentrates. This study sought to estimate the health and economic burden of haemophilia in Belgium. This is the first study of its type to be conducted, and reflects the Belgian authorities' growing interest for haemophilia as part of their priority planning for rare and chronic diseases. METHODS: A probabilistic model was developed in order to estimate the lifetime haemophilia burden for the 2011 birth-year Belgian cohort. The health burden was initially expressed in terms of disability-adjusted life years (DALYs), the number of healthy life years lost due to living with disability and dying prematurely. An incidence perspective was used in line with World Health Organization recommendations. The economic burden calculated from direct and indirect haemophilia-related costs was expressed in euros. Data were drawn from the literature if none were available from federal institutions or health insurance. Disability weights for DALY calculation were derived using generic quality-of-life tools such as SF-6D from the SF-36 (36-item Short-Form Health Survey; for adults) and KINDL (generic quality-of-life instrument; for children) compared to population norms. Analyses were stratified according to haemophilia type and severity. RESULTS: In Belgium, haemophilia resulted in 145 undiscounted and unweighted DALYs in total (95% credible interval [CrI] = 90-222), which represents an average of 11 DALYs per incident case with haemophilia (95% CrI = 8-15) during his life, varying according to haemophilia severity (17 DALYs for severe haemophilia, 12 DALYs for moderate, and 4 DALYs for mild). Mean total lifetime costs reached €7.8 million per people with haemophilia, 94.3% being direct costs and 5.7% indirect costs. Clotting factors accounted for 82.5% of direct costs. CONCLUSIONS: Haemophilia represents both an economic and health burden, especially regarding individual health on an individual patient level. Initiatives to counteract this burden should be clearly identified and given full support, as this burden is likely to increase in the future, especially from an economic perspective. Our study may also contribute towards a better global evaluation of haemophilia in the future.

Like mother, like daughter? Mother's history of cervical cancer screening and daughter's Human Papillomavirus vaccine uptake in Flanders (Belgium).

OBJECTIVE: We investigated whether and to what extent the uptake of the Human Papillomavirus (HPV) vaccine by girls aged 12-18 was related to the cervical cancer screening history of age-appropriate older female household members (assumed to be their mothers) in Flanders (Belgium). METHODS: We studied administrative records on 127,854 female members of the National Alliance of Christian Mutualities, which is the largest health insurance fund in Flanders. Reimbursement data for HPV vaccination of girls for the period 2007-2009 were linked with reimbursement data for cervical cancer screening of their mothers in the three preceding years. A multilevel logit model was used to study associations between both preventive behaviors. In the model we controlled for both the girl's and the mother's age, the province of residence and the socio-economic background of the family. RESULTS: A clear association between a mother's history of participation in cervical cancer screening and her daughter's HPV vaccination initiation was found. The conditional odds of HPV vaccination initiation were more than 4 times higher for girls whose mother had one Pap test than for girls whose mother had none (odds ratio [OR]=4.5; 95% confidence interval [CI]=3.5-5.9). For girls whose mother had three or more Pap tests, the conditional odds were 16 times higher than for girls whose mother did not have any pap tests ([OR]=16.0; 95% [CI]=12.1-21.2). The effect of screening (having received 1 pap smear as compared to none) was larger for girls living in neighborhoods with the lowest median income ([OR]=6.0, 95% [CI]=3.6-10.1). CONCLUSION: In a situation where both cervical cancer screening and HPV vaccination are opportunistic, we found evidence that these preventive behaviors cluster within families.

Dynamics of HPV vaccination initiation in Flanders (Belgium) 2007-2009: a Cox regression model.

BACKGROUND: We investigated dynamic patterns and predictors of HPV vaccination initiation in Flanders (Belgium) by girls aged 12 to 18, between 2007 and 2009, the period immediately after the introduction of the HPV vaccines on the Belgian market. During this period the initiative for vaccination was taken by the girl, her family or the general practitioner/pediatrician/gynecologist. METHODS: We used a Cox regression model with time constant and time varying predictors to model hazard rates of HPV vaccination initiation. The sample existed of 117,151 female members of the National Alliance of Christian Mutualities, the largest sickness fund in Flanders. RESULTS: The study showed that the hazard of HPV vaccination initiation was higher (1) for older girls, (2) for girls with a more favorable socio-economic background, (3) under more generous reimbursement regimes (with this effect being more pronounced for girls with weak socioeconomic backgrounds), (4) for girls that were informed personally about the reimbursement rules. CONCLUSIONS: When the initiative for HPV vaccination lies with the girls, their families or the physicians (no organized setting) the uptake of the vaccines is affected by both individual and organizational factors.

Cancer during pregnancy: an analysis of 215 patients emphasizing the obstetrical and the neonatal outcomes.

PURPOSE: The aim of this study was to assess the management and the obstetrical and neonatal outcomes of pregnancies complicated by cancer. PATIENTS AND METHODS: In an international collaborative setting, patients with invasive cancer diagnosed during pregnancy between 1998 and 2008 were identified. Clinical data regarding the cancer diagnosis and treatment and the obstetric and neonatal outcomes were collected and analyzed. RESULTS: Of 215 patients, five (2.3%) had a pregnancy that ended in a spontaneous miscarriage and 30 (14.0%) pregnancies were interrupted. Treatment was initiated during pregnancy in 122 (56.7%) patients and postpartum in 58 (27.0%) patients. The most frequently encountered cancer types were breast cancer (46%), hematologic malignancies (18%), and dermatologic malignancies (10%). The mean gestational age at delivery was 36.3 +/- 2.9 weeks. Delivery was induced in 71.7% of pregnancies, and 54.2% of children were born preterm. In the group of patients prenatally exposed to cytotoxic treatment, the prevalence of preterm labor was increased (11.8%; P = .012). Furthermore, in this group a higher proportion of small-for-gestational-age children (birth weight below 10th percentile) was observed (24.2%; P = .001). Of all neonates, 51.2% were admitted to a neonatal intensive care unit, mainly (85.2%) because of prematurity. There was no increased incidence of congenital malformations. CONCLUSION: Pregnant cancer patients should be treated in a multidisciplinary setting with access to maternal and neonatal intensive care units. Prevention of iatrogenic prematurity appears to be an important part of the treatment strategy.

The health and economic burden of rotavirus disease in Belgium.

For health economic evaluations of rotavirus vaccination, estimates of the health and cost burden of rotavirus are required. Due to differences in health care systems and surveillance organisations, this is difficult to achieve by imputing estimates from one country to others. This study aimed to estimate the burden of rotavirus disease in Belgium. In children younger than 7 years of age, rotavirus is predicted to account annually for about 5,600 hospitalisations (676:100,000 children); 26,800 outpatient, general practitioner and paediatrician visits; and about 44,600 episodes for which no medical care is sought. This burden is estimated to represent direct costs of 7.7 million Euro and indirect costs of 12.8 million Euro. Rotavirus disease causes a substantial health and economic burden in Belgium.

Expression profiling to predict the clinical behaviour of ovarian cancer fails independent evaluation.

BACKGROUND: In a previously published pilot study we explored the performance of microarrays in predicting clinical behaviour of ovarian tumours. For this purpose we performed microarray analysis on 20 patients and estimated that we could predict advanced stage disease with 100% accuracy and the response to platin-based chemotherapy with 76.92% accuracy using leave-one-out cross validation techniques in combination with Least Squares Support Vector Machines (LS-SVMs). METHODS: In the current study we evaluate whether tumour characteristics in an independent set of 49 patients can be predicted using the pilot data set with principal component analysis or LS-SVMs. RESULTS: The results of the principal component analysis suggest that the gene expression data from stage I, platin-sensitive advanced stage and platin-resistant advanced stage tumours in the independent data set did not correspond to their respective classes in the pilot study. Additionally, LS-SVM models built using the data from the pilot study - although they only misclassified one of four stage I tumours and correctly classified all 45 advanced stage tumours - were not able to predict resistance to platin-based chemotherapy. Furthermore, models based on the pilot data and on previously published gene sets related to ovarian cancer outcomes, did not perform significantly better than our models. CONCLUSION: We discuss possible reasons for failure of the model for predicting response to platin-based chemotherapy and conclude that existing results based on gene expression patterns of ovarian tumours need to be thoroughly scrutinized before these results can be accepted to reflect the true performance of microarray technology.

Predicting the prognosis of breast cancer by integrating clinical and microarray data with Bayesian networks.

MOTIVATION: Clinical data, such as patient history, laboratory analysis, ultrasound parameters--which are the basis of day-to-day clinical decision support--are often underused to guide the clinical management of cancer in the presence of microarray data. We propose a strategy based on Bayesian networks to treat clinical and microarray data on an equal footing. The main advantage of this probabilistic model is that it allows to integrate these data sources in several ways and that it allows to investigate and understand the model structure and parameters. Furthermore using the concept of a Markov Blanket we can identify all the variables that shield off the class variable from the influence of the remaining network. Therefore Bayesian networks automatically perform feature selection by identifying the (in)dependency relationships with the class variable. RESULTS: We evaluated three methods for integrating clinical and microarray data: decision integration, partial integration and full integration and used them to classify publicly available data on breast cancer patients into a poor and a good prognosis group. The partial integration method is most promising and has an independent test set area under the ROC curve of 0.845. After choosing an operating point the classification performance is better than frequently used indices.

Comparison of the PhoPQ regulon in Escherichia coli and Salmonella typhimurium.

The PhoPQ two-component system acts as a transcriptional regulator that responds to Mg(2+) starvation both in Escherichia coli and Salmonella typhimurium (Garcia et al. 1996; Kato et al. 1999). By monitoring the availability of extracellular Mg(2+), this two-component system allows S. typhimurium to sense the transition from an extracellular environment to a subcellular location. Concomitantly with this transition, a set of virulence factors essential for survival in the intracellular environment is activated by the PhoPQ system (Groisman et al. 1989; Miller et al. 1989). Compared to nonpathogenic strains, such as E. coli K12, the PhoPQ regulon in pathogens must contain target genes specifically contributing to the virulence phenotype. To verify this hypothesis, we compared the composition of the PhoPQ regulon between E. coli and S. typhimurium using a combination of expression experiments and motif data. PhoPQ-dependent genes in both organisms were identified from PhoPQ-related microarray experiments. To distinguish between direct and indirect targets, we searched for the presence of the regulatory motif in the promoter region of the identified PhoPQ-dependent genes. This allowed us to reconstruct the direct PhoPQ-dependent regulons in E. coli K12 and S. typhimurium LT2. Comparison of both regulons revealed a very limited overlap of PhoPQ-dependent genes between both organisms. These results suggest that the PhoPQ system has acquired a specialized function during evolution in each of these closely related species that allows adaptation to the specificities of their lifestyles (e.g., pathogenesis in S. typhimurium).

M@CBETH: a microarray classification benchmarking tool.

Microarray classification can be useful to support clinical management decisions for individual patients in, for example, oncology. However, comparing classifiers and selecting the best for each microarray dataset can be a tedious and non-straightforward task. The M@CBETH (a MicroArray Classification BEnchmarking Tool on a Host server) web service offers the microarray community a simple tool for making optimal two-class predictions. M@CBETH aims at finding the best prediction among different classification methods by using randomizations of the benchmarking dataset. The M@CBETH web service intends to introduce an optimal use of clinical microarray data classification.

Systematic benchmarking of microarray data classification: assessing the role of non-linearity and dimensionality reduction.

MOTIVATION: Microarrays are capable of determining the expression levels of thousands of genes simultaneously. In combination with classification methods, this technology can be useful to support clinical management decisions for individual patients, e.g. in oncology. The aim of this paper is to systematically benchmark the role of non-linear versus linear techniques and dimensionality reduction methods. RESULTS: A systematic benchmarking study is performed by comparing linear versions of standard classification and dimensionality reduction techniques with their non-linear versions based on non-linear kernel functions with a radial basis function (RBF) kernel. A total of 9 binary cancer classification problems, derived from 7 publicly available microarray datasets, and 20 randomizations of each problem are examined. CONCLUSIONS: Three main conclusions can be formulated based on the performances on independent test sets. (1) When performing classification with least squares support vector machines (LS-SVMs) (without dimensionality reduction), RBF kernels can be used without risking too much overfitting. The results obtained with well-tuned RBF kernels are never worse and sometimes even statistically significantly better compared to results obtained with a linear kernel in terms of test set receiver operating characteristic and test set accuracy performances. (2) Even for classification with linear classifiers like LS-SVM with linear kernel, using regularization is very important. (3) When performing kernel principal component analysis (kernel PCA) before classification, using an RBF kernel for kernel PCA tends to result in overfitting, especially when using supervised feature selection. It has been observed that an optimal selection of a large number of features is often an indication for overfitting. Kernel PCA with linear kernel gives better results.

INCLUSive: A web portal and service registry for microarray and regulatory sequence analysis.

INCLUSive is a suite of algorithms and tools for the analysis of gene expression data and the discovery of cis-regulatory sequence elements. The tools allow normalization, filtering and clustering of microarray data, functional scoring of gene clusters, sequence retrieval, and detection of known and unknown regulatory elements using probabilistic sequence models and Gibbs sampling. All tools are available via different web pages and as web services. The web pages are connected and integrated to reflect a methodology and facilitate complex analysis using different tools. The web services can be invoked using standard SOAP messaging. Example clients are available for download to invoke the services from a remote computer or to be integrated with other applications. All services are catalogued and described in a web service registry. The INCLUSive web portal is available for academic purposes at http://www.esat.kuleuven.ac.be/inclusive.