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Oliver Kuss

Publications and source records attributed to Oliver Kuss.

14 recordsLinked to original sources
PubMed2006

Cluster-crossover design: a method for limiting clusters level effect in community-intervention studies.

The cluster-crossover design can be used for clinical trials comparing two or more interventions in a naturally formed study population, i.e. a cluster. This design differs from that of a crossover study, in that the treatment sequence is allocated at the cluster level. A cluster-crossover study can thus be considered as a cluster-randomized controlled study with additional periodic cluster-randomization(s) or treatment permutation(s) during the study. The data must be analyzed with hierarchical models with random effects in order to allow for different outcome probabilities in each period, cluster and cluster-period. Original data from two published field studies of hospital infection control based on this design are used here to illustrate the impact of different statistical models on the interpretation of the results.

Clinical Trials as Topic↗
PubMed2006

Endothelial Protection, AT1 blockade and Cholesterol-Dependent Oxidative Stress: the EPAS trial.

BACKGROUND: Statins and angiotensin type 1 (AT1) receptor blockers reduce cardiovascular mortality and morbidity. In the Endothelial Protection, AT1 blockade and Cholesterol-Dependent Oxidative Stress (EPAS) trial, impact of independent or combined statin and AT1 receptor blocker therapy on endothelial expression of anti-atherosclerotic and proatherosclerotic genes and endothelial function in arteries of patients with coronary artery disease were tested. METHODS AND RESULTS: Sixty patients with stable coronary artery disease undergoing elective coronary artery bypass grafting (CABG) surgery were randomized 4 weeks before surgery to: (A) control without inhibition of renin-angiotensin system or statin; (B) statin (pravastatin 40 mg/d); (C) AT1 blockade (irbesartan 150 mg/d); or (D) combination of statin and AT1 blocker in same dosages. Primary end point was a priori therapy-dependent regulation of an anti-atherosclerotic endothelial expression quotient Q including mRNA expression (in arbitrary units measured by real-time polymerase chain reaction) of endothelial nitric oxide synthase and C-type natriuretic peptide, divided by expression of oxidized low-density lipoprotein receptor LOX-1 and NAD(P)H oxidase subunit gp91phox in left internal mammary arteries biopsies obtained by CABG surgery; 49 patients completed the study. Statin therapy increased lnQ from 3.2+/-0.4 to 4.4+/-0.4 significantly versus control. AT(1) blockade showed a trend to increase lnQ to 4.2+/-0.5. Combination of statin and AT1 blocker further increased lnQ to 5.1+/-0.6, but a putative interaction of both therapies in lnQ was not significant. Furthermore, preoperative therapy with statin, AT1 blocker and their combination improved endothelial function in internal mammary artery rings. CONCLUSIONS: Statin and AT1 blocker therapy independently and in combination improve an anti-atherosclerotic endothelial expression quotient and endothelial function.

Angiotensin II Type 1 Receptor Blockers↗
PubMed2006

Model-based clustering of binary longitudinal atopic dermatitis disease histories by latent class mixture models.

Atopic dermatitis is a skin disease which affects mainly children, has a very strong genetical component, and manifests itself clinically as flexural excema in connection with torturing itching. The course of disease is notoriously changeable and runs in phases, therefore it is difficult to predict the future course of disease. To improve prediction it would be interesting to identify clusters of children with different disease histories because this would shed light on common genetic and environmental risk factors. We use, relying on previous work of Nagin, a Latent class mixture model to estimate, in a data-dependent and model-based fashion, a clustering of typical binary atopic dermatitis disease histories in children. The data were collected from 1990 to 1997 in the so called MAS-study, a prospective cohort study of 1314 children in five German cities. The original method of Nagin is extended in two different aspects, first we use bootstrap confidence intervals to account for uncertainty in curve fitting, and second, we propose to model covariates for cluster membership by Anderson's Stereotype regression model. We feel that the Latent class mixture model is a valuable tool for assessing the course of atopic dermatitis, yielding a wealth of communicable and graphically displayable results.

Algorithms↗
PubMed2005

Cardiovascular disease, risk factors and heart rate variability in the elderly general population: design and objectives of the CARdiovascular disease, Living and Ageing in Halle (CARLA) Study.

BACKGROUND: The increasing burden of cardiovascular diseases (CVD) in the ageing population of industrialized nations requires an intensive search for means of reducing this epidemic. In order to improve prevention, detection, therapy and prognosis of cardiovascular diseases on the population level in Eastern Germany, it is necessary to examine reasons for the East-West gradient of CVD morbidity and mortality, potential causal mechanisms and prognostic factors in the elderly. Psychosocial and nutritional factors have previously been discussed as possible causes for the unexplained part of the East-West gradient. A reduced heart rate variability appears to be associated with cardiovascular disease as well as with psychosocial and other cardiovascular risk factors and decreases with age. Nevertheless, there is a lack of population-based data to examine the role of heart rate variability and its interaction with psychosocial and nutritional factors regarding the effect on cardiovascular disease in the ageing population. There also is a paucity of epidemiological data describing the health situation in Eastern Germany. Therefore, we conduct a population-based study to examine the distribution of CVD, heart rate variability and CVD risk factors and their associations in an elderly East German population. This paper describes the design and objectives of the CARLA Study. METHODS/DESIGN: For this study, a random sample of 45-80 year-old inhabitants of the city of Halle (Saale) in Eastern Germany was drawn from the population registry. By the end of the baseline examination (2002-2005), 1750 study participants will have been examined. A multi-step recruitment strategy aims at achieving a 70% response rate. Detailed information is collected on own and family medical history, socioeconomic, psychosocial, behavioural and biomedical factors. Medical examinations include anthropometric measures, blood pressure of arm and ankle, a 10-second and a 20-minute electrocardiogram, a general physical examination, an echocardiogram, and laboratory analyses of venous blood samples. On 200 participants, a 24-hour electrocardiogram is recorded. A detailed system of quality control ensures high data quality. A follow-up examination is planned. DISCUSSION: This study will help to elucidate pathways to CVD involving autonomic dysfunction and lifestyle factors which might be responsible for the CVD epidemic in some populations.

Aged↗
PubMed2004

Survival of patients in clinical stages I-IIIb of non-small-cell lung cancer treated with radiation therapy alone. Results of a population-based study in Southern Saxony-Anhalt.

BACKGROUND AND PURPOSE: Up to now, evidence about survival of patients with non-small-cell lung cancer treated with radiation therapy alone is only available from clinical studies. The authors analyzed survival experience depending on several prognostic factors from a population-based cancer registry and compared this to survival data from the literature. PATIENTS AND METHODS: Between April 1996 and September 1999, 1,696 patients with lung cancer were recruited by the Halle Lung Cancer (HALLUCA) Study. 1,183 patients were diagnosed as having non-small-cell lung cancer, and 188 in clinical stages I-IIIb (15.9%) were treated with radiation therapy alone. RESULTS: The median survival time of all patients was 10.2 months, the 2-year overall survival rate amounted to 15.8%. Besides tumor stage, radiation dose was found to be a statistically significant prognostic factor for survival in univariate analysis. The median survival time was 4.2 months for 66 patients treated with < 50 Gy, 10.7 months for 80 patients treated with 50 to < 60 Gy, and 18.9 months for 42 patients treated with >/= 60 Gy; the corresponding 2-year overall survival rates were 8.7%, 13.4%, und 35.2%. The significant influence of dose persisted even after adjustment for different confounders in a Cox regression model. CONCLUSION: Patients treated with 50 to < 60 Gy under a potentially curative therapeutic regimen had a significantly lower survival, compared to patients treated with >/= 60 Gy. In terms of quality assurance, the large proportion of patients treated with radiation doses below the curative range of >/= 60 Gy was unexpected.

Aged↗
PubMed2003

Age-dependent depression in circulating endothelial progenitor cells in patients undergoing coronary artery bypass grafting.

OBJECTIVES: The effect of patient age on circulating endothelial progenitor cells (EPCs) and their mobilization during coronary artery bypass grafting (CABG) was assessed. BACKGROUND: The EPCs are able to contribute to reparative neovascularization after tissue ischemia. In experimental models, reparative neovascularization is impaired in senescent animals, but the role of EPCs in this impairment, especially in humans, is unknown. METHODS: In 50 consecutive patients (43 to 80 years old) with stable coronary artery disease undergoing CABG, the numbers of EPCs and the plasma levels of interleukin (IL)-6, IL-8, IL-10, and IL-18, as well as vascular endothelial growth factor (VEGF) and placental growth factor, were determined preoperatively, after coming off bypass, and 6, 12, 24, and 72 h postoperatively. RESULTS: Preoperative values of EPCs were lowered with increasing age, similar to the lowering of plasma VEGF levels. These age-associated decreases could not be explained by differences in atherosclerotic risk factors or cardiac function. Bypass surgery induced a rapid mobilization in EPCs, IL-6, IL-8, IL-10, and VEGF, with a peak 6 h postoperatively. Persistently lower levels of EPCs and VEGF throughout the observation period were observed in patients >69 years old, which could not be explained by differences in the operative procedure or inflammatory IL activation. CONCLUSIONS: Despite a significant increase in EPCs and release of cytochemokines during CABG, age is a major limiting factor for mobilization of EPCs. Further studies are necessary to improve the strategies for mobilization, ex vivo expansion, and re-transplantation of EPCs in aging patients.

Adult↗
PubMed2002

Global goodness-of-fit tests in logistic regression with sparse data.

The logistic regression model has become the standard analysing tool for binary responses in medical statistics. Methods for assessing goodness-of-fit, however, are less developed where this problem is especially pronounced in performing global goodness-of-fit tests with sparse data, that is, if the data contain only a small numbers of observations for each pattern of covariate values. In this situation it has been known for a long time that the standard goodness-of-fit tests (residual deviance and Pearson chi-square) behave unsatisfactorily if p-values are calculated from the chi(2)-distribution. As a remedy in this situation the Hosmer-Lemeshow test is frequently recommended; it relies on a new grouping of the observations to avoid sparseness, where this grouping depends on the estimated probabilities from the model. It has been shown, however, that the Hosmer-Lemeshow test also has some deficiencies, for example, it depends heavily on the calculating algorithm and thus different implementations might lead to different conclusions regarding the fit of the model. We present some alternative tests from the statistical literature which should also perform well with sparse data. Results from a simulation study are given which show that there exist some goodness-of-fit tests (for example, the Farrington test) that have good properties regarding size and power and that even outperform the Hosmer-Lemeshow test. We illustrate the various tests with an example from dermatology on occupational hand eczema in hairdressers.

Beauty Culture↗
PubMed2002

Induction of endotoxin tolerance improves lung function after warm ischemia in dogs.

In shock models, induction of endotoxin tolerance (ET) is known to have a protective effect. The present study was designed to explore if ET is effective in protecting lungs from reperfusion injury. Twelve foxhounds were used as experimental animals. After a left thoracotomy, the left hilum was clamped for 3 h, followed by 8 h of reperfusion. In the treatment group (ET, n = 6), dogs were pretreated with incremental daily endotoxin doses of up to 60 microg/kg on day 6. The ischemia and reperfusion experiment was carried out on day 9. Control group animals (n = 6) were not subjected to endotoxin. After 8 h of observation, functional parameters of the reperfused lung of the ET and the control group were statistically different (P < 0.05) with respect to Po(2) [ET vs. control: 172.7 +/- 12.9 vs. 66.1 +/- 7.2 (SE) mmHg], compliance (16.0 +/- 1.2 vs. 8.3 +/- 1.0 ml/0.1 kPa), and the wet-to-dry ratio (9.4 +/- 0.8 vs. 16.7 +/- 1.2). After 3 h of warm ischemia and 8 h of reperfusion, pulmonary function and lung water content improved in the endotoxin-tolerant group.

Animals↗
PubMed2002

Pulmonary blood flow is inhomogeneously reduced after Euro Collins-preservation and lung transplantation.

BACKGROUND: Vasoconstriction after lung transplantation is a well-known phenomenon, but only limited information is available on blood flow distribution after ischemia and reperfusion. The aim of our study was to determine the regional flow characteristics in transplanted and native dog lungs after 24 hours of cold storage and preservation with Euro Collins-solution. METHODS: Six pairs of weight-matched Foxhounds (25 to 30 kg) were used. In donors and recipients, aortic and pulmonary artery catheters were inserted percutaneously and a reference withdrawal catheter was placed into the main pulmonary artery. For preservation, the lungs were perfused with modified Euro Collins-solution and stored at 4 degrees C. After 24 hours, the left lung was transplanted. Regional pulmonary blood flow was assessed by injection of colored microspheres into the right atrium using the reference withdrawal technique. Measurements of regional pulmonary blood flow were conducted twice in donors and recipients (baseline and 3 hours after reperfusion). Tissue samples from five distinct regions (apical, medial, dorsal, ventral, and lateral) were taken to assess regional pulmonary blood flow and wet-dry ratios. RESULTS: The relative (per thousand Confidence Intervals/100 mg dry weight) regional pulmonary blood flow was significantly reduced in the transplanted lung but not in the native organ. This reduction was most pronounced in apical regions and smallest in regions close to the hilum. Edema formation occurred in both lungs, as judged from wet-to-dry ratios of lung tissue specimen. CONCLUSIONS: Two separate processes can be observed after single lung transplantation: (1) reduced regional pulmonary blood flow, which is a regional phenomenon restricted to the transplanted organ, and (2) extensive edema affecting both the transplanted and the native lung.

Animals↗
PubMed2002

Importance of irritant contact dermatitis in occupational skin disease.

BACKGROUND: Irritant contact dermatitis (ICD), provoked by work materials or workflows, is believed to be a frequent cause of occupational skin disease (OSD). Data of incidence rates of ICD within different occupations are inadequate. OBJECTIVE: We conducted a population-based study to identify occupational groups at risk for irritant and allergic contact dermatitis (ACD). METHODS: The data are based on all workers' compensation claims reported to our register of OSDs in Northern Bavaria [Berufskrankheitenregister Haut-Nordbayern (BKH-N)], Germany. RESULTS: From 1990 to 1999, 5285 patients had their cases completely assessed and recorded by government-employed physicians. We calculated the incidence rates of ICD and ACD in various occupations, divided into 24 occupational groups, in co-operation with the German State Institute of Labor and Occupation; there were a known total number of employees in each of the occupations. In these groups 3097 (59%) patients with OSD were observed, with an overall annual incidence rate of 4.5 patients per 10,000 workers for ICD, compared with 4.1 patients per 10,000 workers for ACD. The highest ICD annual incidence rates were found in hairdressers (46.9 per 10,000 workers per year), bakers (23.5 per 10,000 workers per year), and pastry cooks (16.9 per 10,000 workers per year); at the same time ICD was the main diagnosis of OSD in pastry cooks (76%), cooks (69%), food processing industry workers and butchers (63%), mechanics (60%), and locksmiths and automobile mechanics (59%). The results of a questionnaire showed frequent skin contact with detergents (52%), disinfectants (24%), and acidic and alkaline chemicals (24%) in the workplace. CONCLUSION: Based on the incidence data of the BKH-N, this study identified occupational groups with a high risk of ICD. Different frequencies of ICD and ACD within a single group are demonstrated. The frequent usage of detergents is being addressed because of the introduction of German legislation of recent date (the Approved Code of Practice 531 on 'wet work').

Adult↗
PubMedDate not supplied

Empirical studies assessing the quality of health information for consumers on the world wide web: a systematic review.

CONTEXT: The quality of consumer health information on the World Wide Web is an important issue for medicine, but to date no systematic and comprehensive synthesis of the methods and evidence has been performed. OBJECTIVES: To establish a methodological framework on how quality on the Web is evaluated in practice, to determine the heterogeneity of the results and conclusions, and to compare the methodological rigor of these studies, to determine to what extent the conclusions depend on the methodology used, and to suggest future directions for research. DATA SOURCES: We searched MEDLINE and PREMEDLINE (1966 through September 2001), Science Citation Index (1997 through September 2001), Social Sciences Citation Index (1997 through September 2001), Arts and Humanities Citation Index (1997 through September 2001), LISA (1969 through July 2001), CINAHL (1982 through July 2001), PsychINFO (1988 through September 2001), EMBASE (1988 through June 2001), and SIGLE (1980 through June 2001). We also conducted hand searches, general Internet searches, and a personal bibliographic database search. STUDY SELECTION: We included published and unpublished empirical studies in any language in which investigators searched the Web systematically for specific health information, evaluated the quality of Web sites or pages, and reported quantitative results. We screened 7830 citations and retrieved 170 potentially eligible full articles. A total of 79 distinct studies met the inclusion criteria, evaluating 5941 health Web sites and 1329 Web pages, and reporting 408 evaluation results for 86 different quality criteria. DATA EXTRACTION: Two reviewers independently extracted study characteristics, medical domains, search strategies used, methods and criteria of quality assessment, results (percentage of sites or pages rated as inadequate pertaining to a quality criterion), and quality and rigor of study methods and reporting. DATA SYNTHESIS: Most frequently used quality criteria used include accuracy, completeness, readability, design, disclosures, and references provided. Fifty-five studies (70%) concluded that quality is a problem on the Web, 17 (22%) remained neutral, and 7 studies (9%) came to a positive conclusion. Positive studies scored significantly lower in search (P =.02) and evaluation (P =.04) methods. CONCLUSIONS: Due to differences in study methods and rigor, quality criteria, study population, and topic chosen, study results and conclusions on health-related Web sites vary widely. Operational definitions of quality criteria are needed.

Evaluation Studies as Topic↗