• An adjustable fetal weight standard for twins: a statistical modeling study

      Zhang, Jun; Mikolajczyk, Rafael; Lei, Xiaoping; Sun, Luming; Yu, Hongping; Cheng, Weiwei (2015-07-03)
      Abstract Background It is a common practice to use a singleton fetal growth standard to assess twin growth. We aim to create a twin fetal weight standard which is also adjustable for race/ethnicity and other factors. Methods Over half a million twin births of low risk pregnancies in the US, from 1995 to 2004, were used to construct a fetal weight standard. We used the Hadlock’s fetal growth standard and the proportionality principle to make the standard adjustable for other factors such as race/ethnicity. We validated the standard in different race/ethnicities in the US and against previously published curves from around the world. Results The adjustable fetal weight standard has an excellent match with the observed birthweight data in non-Hispanic White, non-Hispanic Black, Hispanics, and Asian from 24 to 38 weeks gestation. It also had a very good fit with cross-sectional data from Australia and Norway, and a longitudinal standard from Brazil. However, our model-based 10th and 90th percentiles differed substantially from studies in Japan and US that used the last menstrual period for estimate of gestational age. Conclusion The adjustable fetal weight standard for twins is a flexible tool and can be used in different populations.
    • An adjustable fetal weight standard for twins: a statistical modeling study.

      Zhang, Jun; Mikolajczyk, Rafael; Lei, Xiaoping; Sun, Luming; Yu, Hongping; Cheng, Weiwei; Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany. (2015)
      It is a common practice to use a singleton fetal growth standard to assess twin growth. We aim to create a twin fetal weight standard which is also adjustable for race/ethnicity and other factors.
    • Alcohol Drinking in University Students Matters for Their Self-Rated Health Status: A Cross-sectional Study in Three European Countries.

      Mikolajczyk, Rafael T; Sebena, Rene; Warich, Julia; Naydenova, Vihra; Dudziak, Urszula; Orosova, Olga; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2016)
      Alcohol drinking was linked to self-rated health in different populations, but the observed association was inconsistent. We studied the association among university students across three European countries with different patterns of drinking.
    • Analysis of Practical Identifiability of a Viral Infection Model.

      Nguyen, Van Kinh; Klawonn, Frank; Mikolajczyk, Rafael; Hernandez-Vargas, Esteban A.; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2016)
      Mathematical modelling approaches have granted a significant contribution to life sciences and beyond to understand experimental results. However, incomplete and inadequate assessments in parameter estimation practices hamper the parameter reliability, and consequently the insights that ultimately could arise from a mathematical model. To keep the diligent works in modelling biological systems from being mistrusted, potential sources of error must be acknowledged. Employing a popular mathematical model in viral infection research, existing means and practices in parameter estimation are exemplified. Numerical results show that poor experimental data is a main source that can lead to erroneous parameter estimates despite the use of innovative parameter estimation algorithms. Arbitrary choices of initial conditions as well as data asynchrony distort the parameter estimates but are often overlooked in modelling studies. This work stresses the existence of several sources of error buried in reports of modelling biological systems, voicing the need for assessing the sources of error, consolidating efforts in solving the immediate difficulties, and possibly reconsidering the use of mathematical modelling to quantify experimental data.
    • Antibiotic use on paediatric inpatients in a teaching hospital in the Gambia, a retrospective study.

      Chaw, Pa Saidou; Schlinkmann, Kristin Maria; Raupach-Rosin, Heike; Karch, André; Pletz, Mathias W; Huebner, Johannes; Nyan, Ousman; Mikolajczyk, Rafael; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018-01-01)
      Antibiotics are useful but increasing resistance is a major problem. Our objectives were to assess antibiotic use and microbiology testing in hospitalized children in the Gambia. We conducted a retrospective analysis of paediatric inpatient data at The Edward Francis Small Teaching Hospital in Banjul, The Gambia. We extracted relevant data from the admission folders of all patients (aged > 28 days to 15 years) admitted in 2015 (January-December), who received at least one antibiotic for 24 h. We also reviewed the microbiology laboratory record book to obtain separate data for the bacterial isolates and resistance test results of all the paediatric inpatients during the study period. Over half of the admitted patients received at least one antibiotic during admission (496/917) with a total consumption of 670.7 Days of Antibiotic Therapy/1000 Patient-Days. The clinical diagnoses included an infectious disease for 398/496, 80.2% of the patients on antibiotics, pneumonia being the most common (184/496, 37.1%). There were 51 clinically relevant bacterial isolates, More than half of the admitted patients received antibiotics. The reported antibiotic resistance was highest to the most commonly used antibiotics such as ampicillin. Efforts to maximize definitive antibiotic indication such as microbiological testing prior to start of antibiotics should be encouraged where possible for a more rational antibiotic use.
    • Association between Embolic Stroke Patterns, ESUS Etiology, and New Diagnosis of Atrial Fibrillation: A Secondary Data Analysis of the Find-AF Trial.

      Maier, Ilko L; Schregel, Katharina; Karch, André; Weber-Krueger, Mark; Mikolajczyk, Rafael T; Stahrenberg, Raoul; Gröschel, Klaus; Bähr, Mathias; Knauth, Michael; Psychogios, Marios-Nikos; Wachter, Rolf; Liman, Jan; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2017)
      Background. Atrial fibrillation (AF) is an important cause of embolic stroke of undetermined source (ESUS). Imaging-patterns like multiple infarcts, simultaneous involvement of different circulations, infarcts of different ages, and isolated cortical infarcts are likely to indicate cardioembolic stroke. The aim of our study was to evaluate the association between embolic stroke patterns, ESUS, and the new diagnosis of AF. Methods. Stroke etiology and imaging characteristics from patients included in the Find-AF study were obtained. Embolic stroke patterns in CT- or MR-imaging were correlated with the diagnosis of ESUS as well as the short- (on baseline ECG and during 7-day Holter) and long-term (12-month follow-up) diagnosis of AF. Results. From 281 patients included in the Find-AF study, 127 (45.2%) patients with ischemic lesions detected in CT or MRI were included. 26 (20.5%) of these patients had ESUS. At least one embolic stroke pattern was detected in 67 (52.7%) patients. Embolic stroke patterns were not associated with ESUS (OR 1.57, 0.65-3.79, p = 0.317), the short-term (OR 0.64, 0.26-1.58, p = 0.327) or long-term diagnosis of AF (OR 0.72, 0.31-1.68, p = 0.448). Conclusions. This secondary data analysis of the Find-AF study could not provide evidence for an association between embolic stroke patterns, ESUS, and the new diagnosis of AF.
    • Association between rates of caesarean section and maternal and neonatal mortality in the 21st century: a worldwide population-based ecological study with longitudinal data.

      Ye, J; Zhang, J; Mikolajczyk, R; Torloni, M R; Gülmezoglu, A M; Betran, A P; Helmholtz Centre for Infectoion Research; Inhoffenstr.7 38124 Braunschweig; Germany. (2015-08-24)
      Caesarean section was initially performed to save the lives of the mother and/or her baby. Caesarean section rates have risen substantially worldwide over the past decades. In this study, we set out to compile all available caesarean section rates worldwide at the country level, and to identify the appropriate caesarean section rate at the population level associated with the minimal maternal and neonatal mortality.
    • Autoimmune thyroiditis as a risk factor for stroke: A historical cohort study

      Karch, A.; Thomas, S. L.; Research group epidemiological and statistical methods, Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany (2014-06-20)
    • Bloodstream infections, antibiotic resistance and the practice of blood culture sampling in Germany: study design of a Thuringia-wide prospective population-based study (AlertsNet).

      Karch, André; Schmitz, Roland P; Rißner, Florian; Castell, Stefanie; Töpel, Sandra; Jakob, Matthias; Brunkhorst, Frank M; Mikolajczyk, Rafael T; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2015)
      Bloodstream infections are a major cause of death worldwide; blood culture (BC) sampling remains the most important tool for their diagnosis. Current data suggest that BC rates in German hospitals are considerably lower than recommended; this points to shortfalls in the application of microbiological analyses. Since early and appropriate BC diagnostics are associated with reduced case fatality rates and a shorter duration of antimicrobial therapy, a multicomponent study for the improvement of BC diagnostics was developed.
    • Care for MRSA carriers in the outpatient sector: a survey among MRSA carriers and physicians in two regions in Germany.

      Raupach-Rosin, Heike; Rübsamen, Nicole; Szkopek, Sebastian; Schmalz, Oliver; Karch, André; Mikolajczyk, Rafael; Castell, Stefanie; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2016)
      Little is known about the management of methicillin-resistant Staphylococcus aureus (MRSA) carriers in the German outpatient sector and about the impact of MRSA on their daily life. Reimbursement for MRSA related costs in the German outpatient sector is available since 2012, but its impact has not been studied yet. The aim of the study was to analyze the outpatient management of MRSA carriers from both, physicians' and MRSA carriers' perspective.
    • Cerebrospinal fluid tau levels are a marker for molecular subtype in sporadic Creutzfeldt-Jakob disease.

      Karch, André; Hermann, Peter; Ponto, Claudia; Schmitz, Matthias; Arora, Amandeep; Zafar, Saima; Llorens, Franc; Müller-Heine, Annika; Zerr, Inga; Helmholtz Centre for infection research, Inhoffenstr. 7, D-38124 Braunschweig, Germany. (2015-05)
      The molecular subtype of sporadic Creutzfeldt-Jakob disease (sCJD) is an important prognostic marker for patient survival. However, subtype determination is not possible during lifetime. Because the rate of disease progression is associated with the molecular subtype, this study aimed at investigating if total tau, a marker of neuronal death, allows premortem diagnosis of molecular subtype when codon 129 genotype is known. Two hundred ninety-six sCJD patients were tested for their cerebrospinal fluid total tau level at the time of diagnosis and were investigated for their sCJD subtype postmortem. There was a significant association between tau levels and the prion protein type in patients with codon 129 MM (p < 0.001), MV (p = 0.004), and VV (p = 0.001) genotype. Receiver operating characteristic analyses showed values of area under the curve of 0.76-0.80 for the different genotypes indicating a good diagnostic validity of the test. Total tau can be used as a diagnostic test for the assessment of prion protein type when codon 129 genotype is known. It provides valuable information for physicians and next of kin about the further course of disease.
    • Changes in incidence of anogenital warts diagnoses after the introduction of human papillomavirus vaccination in Germany-an ecologic study.

      Mikolajczyk, Rafael T; Kraut, Angela A; Horn, Johannes; Schulze-Rath, Renate; Garbe, Edeltraut; BIPS-Institute for Epidemiology and Prevention Research, Bremen, Germany. miko@bips.uni-bremen.de (2013-01)
      In a large health insurance database in Germany, incidence of anogenital warts among 15- to 19-year-old females decreased from 316/100,000 person-years in 2007 to 242 in 2008 (23% reduction, P = 0.0001). The decrease started between the first and second quarter of 2007 (human papillomavirus vaccination was introduced in March 2007).
    • Changes in risk perceptions during the 2014 Ebola virus disease epidemic: results of two consecutive surveys among the general population in Lower Saxony, Germany.

      Obenauer, Julie; Rübsamen, Nicole; Garsevanidze, Ekaterine; Karch, André; Mikolajczyk, Rafael T; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2018-05-15)
      The Ebola virus disease (EVD) outbreak 2014 received extensive news media coverage, which faded out before the outbreak ended. News media coverage impacts risk perception; it is, however, unclear if the components of risk perception (affective and cognitive responses) change differently over time. In an online panel, we asked participants (n = 1376) about EVD risk perceptions at the epidemic's peak (November 2014) and after news media coverage faded out (August 2015). We investigated worry (affective response), perceived likelihood of infection, perceived personal impact, and coping efficacy (dimensions of cognitive response), and knowledge about transmission. Differences between the surveys with respect to manifestations of affective and cognitive dimensions were tested using the Wilcoxon signed-rank test. The association between individual change in knowledge and worries about EVD in the first survey was investigated using linear regression. In November 2014, the survey was filled in by 974 participants. Ten months later, 662 of them were still members of the online panel and were invited to the follow-up survey. Among the 620 respondents, affective response decreased between the surveys. Knowledge about EVD also decreased; however, participants worried about EVD in 2014 had increased knowledge in 2015. Perceived likelihood of infection decreased over time, while perceived personal impact and coping efficacy did not. Risk communication appealing to cognitive reactions by informing clearly on the risk of infection in unaffected countries may decrease inappropriate behaviors.
    • Clustering of developmental delays in Bavarian preschool children - a repeated cross-sectional survey over a period of 12 years.

      Stich, Heribert L; Krämer, Alexander; Mikolajczyk, Rafael T (2014)
      While most children display a normal development, some children experience developmental delays compared to age specific development milestones assessed during school entry examination. Data exist on prevalence of delays in single areas, but there is lack of knowledge regarding the clustering patterns of developmental delays and their determinants.
    • Comorbidities in ADHD children treated with methylphenidate: a database study.

      Kraut, Angela A; Langner, Ingo; Lindemann, Christina; Banaschewski, Tobias; Petermann, Ulrike; Petermann, Franz; Mikolajczyk, Rafael T; Garbe, Edeltraut; Department of Clinical Epidemiology, Leibniz Institute for Prevention Research and Epidemiology - BIPS, Bremen, Germany. (2013)
      Methylphenidate (MPH) is the most common drug treatment of attention deficit / hyperactivity disorder (ADHD) in children. Treatment with MPH is contraindicated in the presence of certain psychiatric, cerebro- and cardiovascular conditions. We assessed MPH treatment prevalence and incidence and the frequency of comorbid conditions related to these contraindications in new MPH users compared to a control group without ADHD and ADHD medication.
    • Comparison of response patterns in different survey designs: a longitudinal panel with mixed-mode and online-only design.

      Rübsamen, Nicole; Akmatov, Manas K; Castell, Stefanie; Karch, André; Mikolajczyk, Rafael; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2017)
      Increasing availability of the Internet allows using only online data collection for more epidemiological studies. We compare response patterns in a population-based health survey using two survey designs: mixed-mode (choice between paper-and-pencil and online questionnaires) and online-only design (without choice).
    • Cost-effectiveness of human papillomavirus vaccination in Germany.

      Damm, Oliver; Horn, Johannes; Mikolajczyk, Rafael T; Kretzschmar, Mirjam E E; Kaufmann, Andreas M; Deleré, Yvonne; Ultsch, Bernhard; Wichmann, Ole; Krämer, Alexander; Greiner, Wolfgang; Hemholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2017)
      The aim of this study was to assess the cost-effectiveness of human papillomavirus (HPV) vaccination in addition to the current cervical cancer screening programme in Germany using a dynamic transmission model.
    • Current and future effects of varicella and herpes zoster vaccination in Germany - Insights from a mathematical model in a country with universal varicella vaccination.

      Horn, Johannes; Karch, André; Damm, Oliver; Kretzschmar, Mirjam E; Siedler, Anette; Ultsch, Bernhard; Weidemann, Felix; Wichmann, Ole; Hengel, Hartmut; Greiner, Wolfgang; Mikolajczyk, Rafael T; Helmholtz-Zentrum für Infektionsforschung GmbH, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2016-07-02)
      Varicella zoster virus (VZV) is primarily known for causing varicella in childhood, but can reactivate again as herpes zoster (HZ) after a period of latency, mainly in persons older than 50 years. Universal varicella vaccination was introduced in Germany in 2004, while HZ vaccination has not been recommended yet. We aimed to quantify the potential long-term effects of universal childhood varicella vaccination and HZ vaccination of the elderly on varicella and HZ incidence in Germany over a time horizon of 100 years, using a transmission model calibrated to pre-vaccination data and validated against early post-vaccination data. Using current vaccination coverage rates of 87% (64%) with one (two) varicella vaccine dose(s), the model predicts a decrease in varicella cases by 89% for the year 2015. In the long run, the incidence reduction will stabilize at about 70%. Under the assumption of the boosting hypothesis of improved HZ protection caused by exposure to VZV, the model predicts a temporary increase in HZ incidence of up to 20% for around 50 years. HZ vaccination of the elderly with an assumed coverage of 20% has only limited effects in counteracting this temporary increase in HZ incidence. However, HZ incidence is shown to decrease in the long-term by 58% as vaccinated individuals get older and finally reach age-classes with originally high HZ incidence. Despite substantial uncertainties around several key variables, the model's results provide valuable insights that support decision-making regarding national VZV vaccination strategies.
    • Deciding on the mode of birth after a previous caesarean section - An online survey investigating women's preferences in Western Switzerland.

      Bonzon, Magali; Gross, Mechthild M; Karch, André; Grylka-Baeschlin, Susanne; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2017-04-21)
      promoting vaginal births after caesarean section (VBAC) for eligible women and increasing rates of successful VBACs are the best strategies to reduce the number of repeat caesarean sections (CS). Knowledge of factors that are associated with women's decision-making around mode of birth after CS is important when developing strategies to promote VBAC. This study assessed which factors are associated with women's preferences for VBAC versus elective repeat caesarean section (ERCS) in a new pregnancy after one previous caesarean in Switzerland.
    • Deficits in knowledge, attitude, and practice towards blood culture sampling: results of a nationwide mixed-methods study among inpatient care physicians in Germany.

      Raupach-Rosin, Heike; Duddeck, Arne; Gehrlich, Maike; Helmke, Charlotte; Huebner, Johannes; Pletz, Mathias W; Mikolajczyk, Rafael; Karch, André; Helmholtz Centre for infection research, Inhoffenstr. 7, 38124 Braunschweig, Germany. (2017-02-15)
      Blood culture (BC) sampling rates in Germany are considerably lower than recommended. Aim of our study was to assess knowledge, attitudes, and practice of physicians in Germany regarding BC diagnostics.