Internal exposure of firefighting instructors to polycyclic aromatic hydrocarbons (PAH) during live fire training

Firefighting instructors in live fire training are inevitably exposed to emissions containing, carcinogenic PAH. The study investigated PAH uptake in a group of firefighting instructors during short-term exposure in live fire training by urinary biomonitoring. Six firefighting instructors (non-smokers) completed five 2 h-training sessions each in a carbonaceous-fired simulation unit using self-containing breathing apparatuses (SCBA). Complying with a minimum time interval of six days between the individual training sessions, the participants provided urine samples before and immediately after, as well as 1, 3, 6, 9, 11, and 18 h after each training session. Samples were analyzed for 10 mono…

t-Tests und Varianzanalysen

Haufig bestehen in empirischen Untersuchungen Hypothesen uber Erwartungswerte von Variablen. Viele der fur solche Hypothesen geeigneten Tests gehen davon aus, dass bestimmte Annahmen uber die Verteilungen der Variablen erfullt sind, dass etwa in allen Bedingungen Normalverteilungen mit derselben Varianz vorliegen. Bevor auf Tests zum Vergleich von Erwartungswerten eingegangen wird, sollen deshalb zunachst jene Verfahren vorgestellt werden, die sich mit der Prufung statistischer Voraussetzungen befassen (Abschn. 10.1). Fur die statistischen Grundlagen dieser Themen vgl. Eid et al. (2015); Kirk (2013) sowie Maxwell und Delaney (2004).

Scalpel cricothyrotomy – with or without speculum: that is the question

Impact of physicians’ participation in non-interventional post-marketing studies on their prescription habits: A retrospective 2-armed cohort study in Germany

Background Non-interventional post-marketing studies (NIPMSs) sponsored by pharmaceutical companies are controversial because, while they are theoretically useful instruments for pharmacovigilance, some authors have hypothesized that they are merely marketing instruments used to influence physicians’ prescription behavior. So far, it has not been shown, to our knowledge, whether NIPMSs actually do have an influence on prescription behavior. The objective of this study was therefore to investigate whether physicians’ participation in NIPMSs initiated by pharmaceutical companies has an impact on their prescription behavior. In addition, we wanted to analyze whether specific characteristics of…

Effects of age on depressive symptomatology and response to antidepressant treatment in patients with major depressive disorder aged 18 to 65 years

Background: There is evidence that symptomatology in patients with major depressive disorder (MDD) changes with age. However, studies comparing depressive symptomatology between different age groups during antidepressant therapy are rare. We compared demographic and clinical characteristics in depressed patients of different age groups at baseline and during treatment. Methods: 889 MDD inpatients were divided into four age groups (18–29, 30–39, 40–49, 50–65 yrs.). Demographic and clinical characteristics including depressive symptomatology (assessed by the Inventory of Depressive Symptoms) were assessed at baseline and weekly during treatment. Results: At baseline, young patients (18–29 yea…

R-Dokumente und Notebooks erstellen

Mit den Paketen knitr (Xie 2020a) und rmarkdown (Allaire et al. 2020) lassen sich R-Auswertungen in Dokumente einbetten, die beschreibenden Text, R-Befehle und die zugehorigen Ergebnisse dieser Befehle integrieren.

Datensätze aufbereiten und aggregieren mit dplyr

In den letzten Jahren hat das Zusatzpaket dplyr stark an Popularitat gewonnen, das Funktionen fur typische Schritte in der Datenaufbereitung enthalt.

Comparative Analyses of Two Established Scores to Assess the Stability of Spinal Bone Metastases Before and After Palliative Radiotherapy

Background and PurposeTo compare two validated spinal instability scores regarding the stabilizing effects and skeletal-related events (SREs) of palliative radiotherapy (RT) in patients with spinal bone metastases (SBM).Materials and MethodsTwo hundred eighty-two osteolytic SBM of lung or breast cancer patients were analyzed for stability before and following RT based on the Spinal Instability Neoplastic Score (SINS) or the Taneichi score. Score concordance was quantified by absolute agreement and Cohen’s kappa coefficient. SREs were defined as fractures or local progression after RT. OS was quantified as the time between the start of RT and death from any cause.ResultsAt 3 and 6 months aft…

Prevalence of Cardiac Disease in Breast Cancer Patients at Time of Diagnosis Compared to the General Female Population in Germany.

<b><i>Background:</i></b> Advances in oncological therapy have significantly improved breast cancer survival; therefore comorbid conditions are becoming more relevant. We investigated the prevalence of prior cardiovascular diseases and risk factors in patients with breast cancer compared to those in the general female population in Germany. <b><i>Methods:</i></b> The PASSOS heart study is a retrospective multicenter cohort study on cardiac late effects in breast cancer patients treated between 1998 and 2008. We analyzed the frequencies of cardiac diseases and cardiovascular risk factors in patients from this cohort as documented in anesthesia …

Zuverlässige und reproduzierbare Datenauswertung

R bietet viele Moglichkeiten, die dabei helfen, Datenauswertungen zuverlassig und reproduzierbar zu machen.

Does chemotherapy improve survival in patients with nodal positive luminal A breast cancer? A retrospective Multicenter Study.

BackgroundIn this study based on the BRENDA data, we investigated the impact of endocrine ± chemotherapy for luminal A, nodal positive breast cancer on recurrence free (RFS) and overall survival (OS). In addition, we analysed if tumor size of luminal A breast cancer influences survival in patients with the same number of positive lymph nodes.MethodsIn this retrospective multi-centre cohort study data of 1376 nodal-positive patients with primary diagnosis of luminal A breast cancer during 2001-2008 were analysed. The results were stratified by therapy and adjusted by age, tumor size and number of affected lymph nodes.ResultsIn our study population, patients had a good to excellent prognosis …

Age and sex related changes in episodic memory function in middle aged and older adults

Age-related change in episodic memory function is commonly reported in older adults. When detected on neuropsychological tests, it may still be difficult to distinguish normal from pathological changes. The present study investigates age-and sex-related changes in a group of healthy middle-aged and older adults, participating in a three-wave study on cognitive aging. The California Verbal Learning test (CVLT-II) was used to assess their episodic memory function. A cross-sectional analysis of results from the first wave showed higher performance in females than males, with a steeper age-related decline in males. This was confirmed in a longitudinal analysis using a mixed effects regression m…

Cohort study of occupational cosmic radiation dose and cancer mortality in German aircrew, 1960-2014.

ObjectivesTo determine cancer mortality compared with the general population and to examine dose-response relationships between cumulative occupational radiation dose and specific cancer outcomes in the German aircrew cohort.MethodsFor a cohort of 26 846 aircrew personnel, standardised mortality ratios (SMR) were calculated. Dose-response analyses were carried out using Poisson regression to assess dose-related cancer risks for the period 1960–2014. Exposure assessment comprises recently available dose register data for all cohort members and newly estimated retrospective cabin crew doses for 1960–2003.ResultsSMR for all-cause, specific cancer groups and most individual cancers were reduced…

Daten importieren und exportieren

Empirische Daten liegen typischerweise in Form von Datensatzen vor, die aus mehreren einzelnen Variablen bestehen. Diese Variablen konnen etwa Stufen eines Gruppierungsfaktors, Zeichenketten oder numerische Werte beinhalten, wobei alle Variablen Daten derselben Beobachtungsobjekte speichern. In diesem Kapitel verschiedene Wege vorgestellt werden, auf denen Daten in R verfugbar gemacht werden konnen. Denn auch wenn es moglich ist, Werte fur einzelne Variablen in R selbst einzugeben, ist dies in der Praxis selten der beste Weg. Stattdessen werden Datensatze meist aus Online-Quellen, Datenbanken oder aus Dateien unterschiedlichen Formats eingelesen, die mit anderen Programmen erstellt wurden.

Diagramme mit ggplot2 erstellen

Daten lassen sich in R mit Hilfe einer Vielzahl von Diagrammtypen grafisch darstellen, wobei hier nur auf eine Auswahl eingegangen werden kann. Fur eine umfassende Dokumentation vgl. Murrell (2018) und Unwin (2015).

Diagramme mit ggplot2

Mit dem Zusatzpaket ggplot2 lassen sich die in Kap. 14 vorgestellten Diagrammtypen ebenfalls erstellen. Dabei ist die Herangehensweise eine grundsatzlich andere: Wahrend der Basisumfang von R fur verschiedene Diagrammarten einzelne Funktionen bereitstellt, werden mit ggplot2 alle Diagrammtypen mit einem einheitlichen System erzeugt. Sind Diagramme des Basisumfangs analog zu einer Leinwand, auf der jede Funktion spater nicht mehr anderbare Elemente aufmalt, reprasentiert ggplot2 alle Diagrammelemente explizit in einem Objekt. Erstellte Diagramme lassen sich uber dieses Objekt weiter verandern, an Funktionen ubergeben und speichern.

Vorhersagegüte prädiktiver Modelle

Da empirische Daten fehlerbehaftet sind, bezieht die Anpassung eines statistischen Modells immer auch die Messfehler mit ein, die Parameterschatzungen orientieren sich daher zu stark an den zufalligen Besonderheiten der konkreten Stichprobe (overfitting). Die Gute der Passung des Modells lasst sich als Funktion \(f(\cdot )\) der Abweichungen \(E = Y -\hat{ Y }\) der Modellvorhersage \(\hat{Y }\) zu den tatsachlichen Werten der vorhergesagten Variable Y quantifizieren. Genauer soll \(\hat{Y }_{X,Y }\, (X')\) die folgende Vorhersage bezeichnen: Zunachst wird ein Modell an einer Stichprobe mit Werten fur Pradiktoren X und Zielvariable Y (Kriterium) angepasst. In die Vorhersagegleichung mit den…

Comorbidity-dependent adherence to guidelines and survival in breast cancer-Is there a role for guideline adherence in comorbid breast cancer patients? A retrospective cohort study with 2137 patients.

In the treatment of breast cancer, decisions on adjuvant treatment reflect individual patient characteristics like age and comorbidity. This study assessed the association between adherence to guidelines for adjuvant treatment and survival while taking into account age at diagnosis and comorbidities. We collected the Charlson comorbidity index at baseline for 2179 women treated for primary breast cancer from 1992 to 2008 who participated in a German retrospective multicenter cohort study. We assessed subsequent adjuvant therapy guideline adherence and survival in relation to baseline comorbidities. Guidelines for adjuvant chemotherapy and radiotherapy were more often violated in patients wi…

Functional genomics indicate that schizophrenia may be an adult vascular-ischemic disorder

AbstractIn search for the elusive schizophrenia pathway, candidate genes for the disorder from a discovery sample were localized within the energy-delivering and ischemia protection pathway. To test the adult vascular-ischemic (AVIH) and the competing neurodevelopmental hypothesis (NDH), functional genomic analyses of practically all available schizophrenia-associated genes from candidate gene, genome-wide association and postmortem expression studies were performed. Our results indicate a significant overrepresentation of genes involved in vascular function (P<0.001), vasoregulation (that is, perivascular (P<0.001) and shear stress (P<0.01), cerebral ischemia (P<0.001), neurode…

Is extracapsular nodal extension in sentinel nodes a predictor for nonsentinel metastasis and is there an impact on survival parameters?-A retrospective single center cohort study with 324 patients

The Z0011 trial has fundamentally changed axillary management in breast cancer patients. However, some important questions remain, like the role of extracapsular nodal extension (ENE) in positive sentinel nodes and the need for further axillary treatment. In this retrospective cohort study, we reviewed and analyzed data from 342 clinically node negative (cN0) breast cancer patients with a positive sentinel node and subsequent axillary lymph node dissection (ALND) from the BRENDA data base. The 104 (30.4%) ENE positive patients had a significantly higher proportion of ≥3 positive axillary lymph nodes (65.0%) compared to ENE negative patients with a positive sentinel node (21.4%). Likewise, E…

Early improvement of executive test performance during antidepressant treatment predicts treatment outcome in patients with Major Depressive Disorder

Executive dysfunctions frequently occur in patients with Major Depressive Disorder and have been shown to improve during effective antidepressant treatment. However, the time course of improvement and its relationship to treatment outcome is unknown. The aim of the study was to assess the test performance and clinical outcome by repetitive assessments of executive test procedures during antidepressant treatment. Executive test performance was assessed in 209 –patients with Major Depressive Disorder (mean age 39.3 ± 11.4 years) and 84 healthy controls five times in biweekly intervals from baseline to week 8. Patients were treated by a defined treatment algorithm within the early medication c…

Daten importieren, exportieren, aufbereiten und aggregieren

Empirische Daten konnen auf verschiedenen Wegen in R verfugbar gemacht werden. Zunachst ist es moglich, Werte durch Zuweisungen etwa in Vektoren zu speichern und diese dann zu Datensatzen zusammenzufugen.

Protective and Risk Factors for Mental Distress and Its Impact on Health-Protective Behaviors during the SARS-CoV-2 Pandemic between March 2020 and March 2021 in Germany

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is posing a global public health burden. These consequences have been shown to increase the risk of mental distress, but the underlying protective and risk factors for mental distress and trends over different waves of the pandemic are largely unknown. Furthermore, it is largely unknown how mental distress is associated with individual protective behavior. Three quota samples, weighted to represent the population forming the German COVID-19 Snapshot Monitoring study (24 March and 26 May 2020, and 9 March 2021 with &gt

A Group Intervention to Promote Resilience in Nursing Professionals: A Randomised Controlled Trial

In this study, a new group intervention program to foster resilience in nursing professionals was tested for efficacy. In total, 72 nurses were recruited and randomised to either an intervention condition or to a wait list control condition. The study had a pre-test, post-test, follow-up design. The eight-week program targeted six resilience factors: cognitive flexibility, coping, self-efficacy, self-esteem, self-care, and mindfulness. Compared to the control group, the intervention group reported a significant improvement in the primary outcome mental health (measured with the General Health Questionnaire) from pre-test (M = 20.79; SD = 9.85) to post-test (M = 15.81; SD = 7.13) with an est…

Estimated radiation exposure of German commercial airline cabin crew in the years 1960-2003 modeled using dose registry data for 2004-2015.

Exposure to ionizing radiation of cosmic origin is an occupational risk factor in commercial aircrew. In a historic cohort of 26,774 German aircrew, radiation exposure was previously estimated only for cockpit crew using a job-exposure matrix (JEM). Here, a new method for retrospectively estimating cabin crew dose is developed. The German Federal Radiation Registry (SSR) documents individual monthly effective doses for all aircrew. SSR-provided doses on 12,941 aircrew from 2004 to 2015 were used to model cabin crew dose as a function of age, sex, job category, solar activity, and male pilots' dose; the mean annual effective dose was 2.25 mSv (range 0.01–6.39 mSv). In addition to an inverse …

Befehle und Daten verwalten

Fur Datenanalysen, die uber wenige Teilschritte hinausgehen, ist die interaktive Arbeitsweise direkt auf der Konsole meist nicht sinnvoll. Stattdessen lasst sich die Auswertung automatisieren, indem alle Befehle zunachst zeilenweise in eine als Skript bezeichnete Textdatei geschrieben werden, die dann ihrerseits von R komplett oder in Teilen ausgefuhrt wird. Analoges gilt fur die Verwaltung empirischer Daten: Gewohnlich werden diese nicht von Hand auf der Konsole eingegeben, sondern in separaten Dateien gespeichert – sei es in R, in Programmen zur Tabellenkalkulation oder in anderen Statistikpaketen. Siehe Abschn. 4.3 fur die Form der Pfadangaben zu Dateien in den folgenden Abschnitten.

Methodological considerations for interrupted time series analysis in radiation epidemiology: an overview

Interrupted time series analysis (ITSA) is a method that can be applied to evaluate health outcomes in populations exposed to ionizing radiation following major radiological events. Using aggregated time series data, ITSA evaluates whether the time trend of a health indicator shows a change associated with the radiological event. That is, ITSA checks whether there is a statistically significant discrepancy between the projection of a pre-event trend and the data empirically observed after the event. Conducting ITSA requires one to consider specific methodological issues due to unique threats to internal validity that make ITSA prone to bias. We here discuss the strengths and limitations of …

Regressionsmodelle für kategoriale Daten und Zähldaten

Das Modell der linearen Regression und Varianzanalyse (Abschn. 6.3, 7.3 und 12.9.1) lasst sich zum verallgemeinerten linearen Modell (GLM, generalized linear model) erweitern, das auch fur Daten einer kategorialen vorherzusagenden Variable Y geeignet ist. Als Pradiktoren lassen sich sowohl kontinuierliche Variablen als auch Gruppierungsfaktoren einsetzen. Ein Spezialfall ist die logistische Regression fur dichotome Y (codiert als 0 und 1). Im Vergleich zur Vorhersage quantitativer Variablen in der linearen Regression wird an diesem Beispiel zunachst folgende Schwierigkeit deutlich (fur Details vgl. Faraway, 2016; Fox & Weisberg, 2011):

Klassische nonparametrische Methoden

Wenn inferenzstatistische Tests zur Datenauswertung herangezogen werden sollen, aber davon ausgegangen werden muss, dass strenge Anforderungen an die Art und Qualitat der erhobenen Daten nicht erfullt sind, kommen viele konventionelle Verfahren womoglich nicht in Betracht. Dagegen haben nonparametrische Methoden weniger restriktive Voraussetzungen und kommen auch bei kleinen Stichproben in Frage (Bortz, Lienert, & Boehnke, 2010; Buning & Trenkler, 1994).

Ionising radiation and lens opacities in interventional physicians: results of a German pilot study

We assessed the feasibility of an epidemiological study on the risk of radiation-related lens opacities among interventional physicians in Germany. In a regional multi-centre pilot study associated with a European project, we tested the recruitment strategy, a European questionnaire on work history for the latter dosimetry calculation and the endpoint assessment. 263 interventional physicians and 129 non-exposed colleagues were invited. Questionnaires assessed eligibility criteria, risk factors for cataract, and work history relating to occupational exposure to ionising radiation, including details on type and amount of procedures performed, radiation sources, and use of protective equipmen…

Body mass index (BMI) in major depressive disorder and its effects on depressive symptomatology and antidepressant response

Obesity is one of the most prevalent somatic comorbidities of Major Depressive Disorder (MDD). We aimed to investigate the relationship between body mass index (BMI) and MDD, the symptomatology of the disorder as well as the outcome of antidepressant treatment.Early medication change (EMC) trial participants with BMI measurement (n = 811) were categorized according to WHO-criteria in normal or low weight (BMI  25), overweight (25- 30), and obese (≥30). Depression severity and BMI was assessed in weekly intervals up to 8 weeks. BMI at baseline and course of BMI during the study were investigated in linear regression models as possible moderators of therapy response. Possible moderators such …

Radiation dose distribution in functional heart regions from tangential breast cancer radiotherapy

Abstract Background and purpose To analyze the distribution of individually-determined radiation dose to the heart and its functional sub-structures after radiotherapy in breast cancer patients treated in Germany during 1998–2008. Material and methods We obtained electronic treatment planning records for 769 female breast cancer patients treated with megavoltage tangential field radiotherapy. All dose distributions were re-calculated using Eclipse with the anisotropic analytical algorithm (AAA) for photon fields, and the electron Monte Carlo algorithm for electron boost fields. Based on individual dose volume histograms for the complete heart and several functional sub-structures, we estima…

The Role of Palliative Radiotherapy in the Treatment of Spinal Bone Metastases from Head and Neck Tumors-A Multicenter Analysis of a Rare Event.

This retrospective multi-center analysis aimed to assess the clinical response and stabilizing effects of palliative radiotherapy (RT) for spinal bone metastases (SBM) in head and neck cancer (HNC), and to establish potential predictive factors for stability and overall survival (OS). Patients included in this analysis were treated at the University Hospitals of Mainz, Freiburg, and Heidelberg between 2001 and 2019. Clinical information was taken from the medical records. The stability of affected vertebral bodies was assessed according to the validated spine instability neoplastic score (SINS) based on CT-imaging before RT, as well as 3 and 6 months after RT. OS was quantified as the time …

Elementare Dateneingabe und -verarbeitung

Die folgenden Abschnitte sollen gleichzeitig die grundlegenden Datenstrukturen in R sowie Moglichkeiten zur deskriptiven Datenauswertung erlautern. Die Reihenfolge der Themen ist dabei so gewahlt, dass die abwechselnd vorgestellten Datenstrukturen und darauf aufbauenden deskriptiven Methoden nach und nach an Komplexitat gewinnen.