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M Blettner

Publications and source records attributed to M Blettner.

At least 19 recordsLinked to original sources
PubMed2005

Risk of cancer after low doses of ionising radiation: retrospective cohort study in 15 countries.

OBJECTIVES: To provide direct estimates of risk of cancer after protracted low doses of ionising radiation and to strengthen the scientific basis of radiation protection standards for environmental, occupational, and medical diagnostic exposures. DESIGN: Multinational retrospective cohort study of cancer mortality. SETTING: Cohorts of workers in the nuclear industry in 15 countries. PARTICIPANTS: 407 391 workers individually monitored for external radiation with a total follow-up of 5.2 million person years. MAIN OUTCOME MEASUREMENTS: Estimates of excess relative risks per sievert (Sv) of radiation dose for mortality from cancers other than leukaemia and from leukaemia excluding chronic lymphocytic leukaemia, the main causes of death considered by radiation protection authorities. RESULTS: The excess relative risk for cancers other than leukaemia was 0.97 per Sv, 95% confidence interval 0.14 to 1.97. Analyses of causes of death related or unrelated to smoking indicate that, although confounding by smoking may be present, it is unlikely to explain all of this increased risk. The excess relative risk for leukaemia excluding chronic lymphocytic leukaemia was 1.93 per Sv (< 0 to 8.47). On the basis of these estimates, 1-2% of deaths from cancer among workers in this cohort may be attributable to radiation. CONCLUSIONS: These estimates, from the largest study of nuclear workers ever conducted, are higher than, but statistically compatible with, the risk estimates used for current radiation protection standards. The results suggest that there is a small excess risk of cancer, even at the low doses and dose rates typically received by nuclear workers in this study.

Dose-Response Relationship, Drug↗
PubMed2005

[Postgraduate qualifications in epidemiology in Germany. Experiences in Berlin, the current situation and future prospects].

The postgraduate Masters Program in Epidemiology (MSc) was established in 2001 in Germany in Bielefeld, Munich and Berlin. The study program is conducted with a common curriculum. Its aim is the qualification of new scientists for jobs in the field of epidemiological research, as well as the training of scientists working in this area. This article reports the experiences of 3 years of classes at the Berlin center. It shows the structure of the program and gives a vision for the future of epidemiological education in Europe.

Berlin↗
PubMed2005

[Statistical analysis of community-based studies -- presentation and comparison of possible solutions with reference to statistical meta-analytic methods].

PURPOSE: The statistical analysis of community-based trials and of other cluster-randomised trials, requires specific statistical methods. We show the consequences of the application of these models for study results, using data of the German Cardiovascular Prevention Study (GCP) as an example. METHODS: Data of 30,285 subjects were analysed, which were collected at the beginning and at the end of the study period. These data had been collected in 7 intervention regions and by national surveys. We grouped data of the national surveys in 7 control clusters to mimick a design typical for cluster-randomised trials. We applied the following statistical models to estimate the effect of the intervention on total cholesterol as well as on systolic blood pressure and the respective confidence intervals: a linear model, a mixed model, and fixed and random effects meta-analyses. RESULTS: While the estimates and confidence intervals for the intervention effect were similar in mixed model analysis and random effects meta-analysis, results from models incorporating fixed effects only were anti-conservative. The underestimation of variance in models incorporating fixed effects only was especially large in the analysis of systolic blood pressure data, where great heterogeneity between intervention communities was observed. Despite seemingly low intraclass correlation coefficients of 0.0019 for total cholesterol and 0.0166 for systolic blood pressure, respectively, the variance of the intervention effect was increased in the mixed model 2.8fold or 17.1fold, respectively, in comparison to the variance estimated in the linear model. Due to this variance inflation the intervention effect on systolic blood pressure lost statistical significance. CONCLUSION: Our results emphasise the importance to account for correlations in community-based trials. Besides the mixed model random effects meta-analysis can be applied as an alternative method.

Adult↗
PubMed2003

Cosmic radiation and cancer mortality among airline pilots: results from a European cohort study (ESCAPE).

Cosmic radiation is an occupational risk factor for commercial aircrews. In this large European cohort study (ESCAPE) its association with cancer mortality was investigated on the basis of individual effective dose estimates for 19,184 male pilots. Mean annual doses were in the range of 2-5 mSv and cumulative lifetime doses did not exceed 80 mSv. All-cause and all-cancer mortality was low for all exposure categories. A significant negative risk trend for all-cause mortality was seen with increasing dose. Neither external and internal comparisons nor nested case-control analyses showed any substantially increased risks for cancer mortality due to ionizing radiation. However, the number of deaths for specific types of cancer was low and the confidence intervals of the risk estimates were rather wide. Difficulties in interpreting mortality risk estimates for time-dependent exposures are discussed.

Adult↗
PubMed2003

Cardiovascular mortality of cockpit crew in Germany: cohort study.

Pilots and other cockpit crew in civil aviation are regularly screened for medical problems that could influence their work performance. Fitness particularly in terms of cardiovascular health is of major importance for this group. While previous studies had shown a low cardiovascular mortality risk of pilots, there is conflicting evidence concerning the prevalence of cardiovascular risk factors in this group. We investigated the cardiovascular mortality of German cockpit crew in a retrospective cohort study. A cohort that included all cockpit crew employed for two German airlines (n=6061) from 1960-1997 was compiled. We calculated the Standardised Mortality Ratio (SMR) and 95% confidence intervals as the ratio of observed and expected numbers of cardiovascular deaths with the German general population as comparison. The influence of age, age at hire and employment duration were analysed in stratified and regression analyses. Overall mortality from cardiovascular causes among cockpit crew was reduced. For mortality from all cardiovascular causes we found an SMR of 0.5(95% CI 0.3-0.6), for acute myocardial infarction the SMR was 0.4 (95% CI 0.3-0.7). Cockpit crew taking up employment at age 30 or later had a more than twofold cardiovascular mortality risk compared with those beginning employment earlier, but there was no risk gradient with duration of employment. Overall, cockpit crew has a relatively low cardiovascular mortality to which a low smoking prevalence and an early detection of cardiovascular health problems are likely to contribute. Cockpit crew employed before age 30 has the lowest cardiovascular mortality risk.

Adult↗
PubMed2003

[New research avenues in exploring causes of death in Germany via regional statistical offices as exemplified by a retrospective cohort study].

In retrospective epidemiological cohort studies the mortality rate of a cohort exposed to certain agents under investigation is compared to the mortality rate of the general population. In Germany, vital status of the cohort is followed up via local population registries. Cause of death of deceased members of the cohort is obtained from death certificates by local health authorities. Since storage time for death certificates is short in some Federal German states, causes of death cannot be obtained if death occurred before storage deadline. Recently it became possible to obtain the cause of death from regional statistical offices. Initial co-operation has been established with the statistical offices of North Rhine Westphalia and Berlin. For a cohort study in the chemical industry, the initially low proportion of causes of death obtained from local health authorities (44.8 %) was increased by 30 % to 74.0 % after obtaining ICD coded causes of death from two regional statistical offices. Further advantages of this new data source are reduction in duration of inquiry time and of overall cost.

Adult↗
PubMed2003

[Assessing social inequality in microcensus data and German national health examination survey].

To analyse the impact of social inequality on health and illness public health officials in Germany request for more data on socio-demographic indicators in official population statistics at Federal and State level. The aim of the study was to examine whether the national sample census Microcensus is suitable for scaling social inequality. For this purpose, coding instructions for calculating social strata index by Winkler were applied to databases of the Microcensus. The results were compared with the German Health Survey, because social data of this survey are already scaled according to the coding instruction for social strata index by Winkler. Data analyses were based on subgroups of North Rhine-Westphalia originated from national samples of Microcensus and German Health Survey. For index indicators "education" and "income" coding structure was transferred to databases of Microcensus without any problems. For index indicator "occupational status" occupational groups were less comparable. This refers to the classification of the occupational status of formerly employed people. However this limitation applies also to employees because the model for "occupational status" is assessed only on a four-year basis. From a methodical point of view it seems to be a problem that "household" has a different meaning in the index by Winkler and Microcensus and is only partly transferable to Microcensus databases. Additionally, identification of the main income earner of the household proved extremely difficult. Therefore, at the present conceptional stage of Microcensus it seems appropriate to classify occupational status as an individual criterion.

Censuses↗
PubMed2003

Mortality among pilots and cabin crew in Greece, 1960-1997.

BACKGROUND: Specific health hazards, among them radiation of cosmic origin, have caused some concern among aircrew in civil aviation in recent years. Several cohort studies in Northern countries have investigated mortality and cancer incidence among aircrew. Our goal was to study the pattern of mortality among Greek commercial airline cockpit and cabin crew. METHODS: We performed a retrospective cohort study including 843 Olympic Airways cockpit crew and 1835 cabin attendants. Standardized mortality ratios (SMR) were calculated based on death rates of the Greek population. Duration of employment as a proxy for occupational exposure was used to stratify the cohort. RESULTS: For cockpit crew, the overall SMR was 0.7 (n = 65, 95% CI: 0.5-0.9). The SMR for all cancers was also significantly decreased (n = 17; SMR = 0.6; 95% CI: 0.3-0.9). Most of this reduction was due to a large deficit in lung cancer deaths (SMR = 0.1; 95% CI: 0.0-0.5). Slight but non-significant increases were noted for brain and liver cancer. The SMR for cardiovascular death was close to unity. Among female cabin attendants the SMR for all causes was 0.8 (95% CI: 0.4-1.3). The SMR for all cancers was 0.8 (95% CI: 0.3-1.7). Mortality from breast cancer was not increased. Among male cabin crew, SMR for all causes was 0.5 (95% CI: 0.3-0.9). Analyses according to duration of employment showed no pattern. CONCLUSIONS: In this first-ever occupational cohort study in Greece, Greek aircrew had a low overall and cancer mortality. Due to the small number of events, the strength of our study is limited. The Greek data will be included in a pooled analysis of European studies.

Aerospace Medicine↗
PubMed2002

Contacts with animals and humans as risk factors for adult brain tumours. An international case-control study.

While numerous studies have addressed the possible role of farming and related exposures as risk factors for brain tumours in adults, few of them have examined the potential effect of exposure to farm animals or pets. In an international multicentre case-control study, we investigated whether residence on a farm, contact with animals, or working in occupations with a high degree of potential contact with animals or humans were associated with brain tumours. Using a common questionnaire, 1177 cases of glioma, 330 with meningioma and 2478 controls from eight centres were interviewed about the exposures and, in particular, about their contacts with nine species of animals: dairy cattle, beef cattle, pigs, horses, sheep, goats, poultry, dogs and cats. Living or working on a farm was not a risk factor, for either glioma or meningioma. Except in some centres, there was no relationship between having contacts with farm animals or pets and the risk of brain tumour, for either type of tumour or either sex. In relation to seven industrial groups involving frequent human and/or animal contacts, no association was apparent for either glioma or meningioma. In relation to 25 occupational groups with potential frequent contact with humans and/or animals, for glioma there was a reduced risk for biological technicians (Odds Ratio (OR)/=0, P=0.01), and general farm workers (OR=0.66, 95% Confidence Interval (CI): 0.5-0.9). For meningioma, there was an increased risk for cooks (OR=2.0; CI: 1.2-3.4). With some exceptions, these results indicate no association between either the type of brain tumour and contacts with animals, or with occupations that include a high level of contact with animals or a high level of contact with humans.

Adult↗
PubMed2002

Transition in cancer patterns among Turks residing in Germany.

Cancer mortality among the 2.1 million Turks residing in Germany is assumed to change from a pattern typical for a developing country towards one of an industrialised country. To test this hypothesis, we compared age-standardised cancer mortality rates among Turkish residents and (West) Germans using death registration data. In addition, we assessed proportional cancer incidence ratios among Turkish cases (n=144) in a German population-based cancer registry. All-cancer mortality 1992-1997 (per 100000) was 34.8 (n=4192) among Turkish men (Germans: 72.3) and 21.5 (n=1862) among Turkish women (Germans: 52.4). Over time, gastric and lung cancer mortality increased among Turkish men, as did breast cancer mortality among Turkish women. The proportional cancer incidence (PCIR) for stomach cancer among men was 2.9 (95% Confidence Interval (CI): 1.7-4.8), and that for breast cancer among women was 0.7 (95% CI: 0.4-1.1). Turks had an increased proportional incidence ratio for non-Hodgkin's lymphoma. Our findings partly support a transition of cancer patterns among Turks in Germany.

Adolescent↗
PubMed2002

Incidence of gastric B-cell lymphomas: a population-based study in Germany.

BACKGROUND: While the clinical and experimental knowledge concerning gastric lymphomas is increasing, there is a scarcity of epidemiological data. PATIENTS AND METHODS: A population-based sample of patients in Franconia and Saarland in Germany was collected from a clinical trial, hospital archives and a cancer registry. RESULTS: Over a period of 3 years, 94 patients with primary gastric lymphoma were recorded out of a total population of 3.5 million. The standardised incidence rates in Saarland and Franconia were 0.7 and 0.8 cases per 100 000, respectively. Patients were predominantly from higher age groups (mean age 62.1 years) and the incidence in men was slightly more than in women (P <0.03). The distribution of histological subtypes in Franconia was as follows: marginal zone B-cell lymphomas (MZBL), 58%; diffuse large-cell B-cell lymphoma (DLBL), 33%; and mixed forms, 9%. Helicobacter pylori could be detected histologically in 84% of all cases, 95% of MZBL cases and 68% of DLBL cases. CONCLUSIONS: Incidence rates of gastric lymphoma in Germany were similar to that in other European countries, except England, where rates are lower. The subtype-specific differences of H. pylori infection rates could be due to differences in carcinogenesis or to secondary changes during malignant transformation.

Adult↗
PubMed2001

[Increasing incidence and mortality of non-Hodgkin lymphomas. An epidemiological review of recent studies on risk factors for non-Hodgkin lymphoma].

BACKGROUND: Non-Hodgkin's lymphoma (NHL) are among the small number of malignant tumors with markedly increasing incidence and mortality rates in the recent past. This trend is particularly obvious in industrialized countries. The causes of the observed increase remain unclear. METHODS: We conducted a Medline search to identify case control and cohort studies on medical, biological and selected environmental risk factors of non-Hodgkin's lymphoma published between 1992 and 1998. Methodological aspects and results of identified studies are presented in tabular form. We furthermore discuss the role of various risk factors for the observed trends in non-Hodgkin's lymphoma. RESULTS: We identified a total of 64 studies. Iatrogenic immunosuppression as well as numerous diseases associated with an impaired immune system have clearly been recognized as etiological factors for non-Hodgkin's lymphoma. However, they can explain only a small percentage of the rate increases of non-Hodgkin's lymphoma. Similarly, the HIV/AIDS epidemic in Germany is responsible only for a small proportion of the rising figures of non-Hodgkin's lymphoma; other viral agents are currently being associated with a few distinct subtypes of non-Hodgkin's lymphoma. Smoking and nutritional factors are weakly or not at all associated with non-Hodgkin's lymphoma and can not account for the disease trends. CONCLUSION: The observed secular rise in incidence and mortality of non-Hodgkin's lymphoma can only partly be explained. New epidemiologic studies should focus on risk factors associated with the function of the immune system and on possible interactions between different etiological factors.

Case-Control Studies↗
PubMed2001

Critical reading of epidemiological papers. A guide.

Many clinicians, medical practitioners and decision makers have no formal training in epidemiology but need to understand and sometimes evaluate results in epidemiologic studies. This paper attempts to give guidance to non-epidemiologists on how to read and evaluate the quality of epidemiologic studies and their results critically. Different methodological issues for evaluating whether the results of a study are causal or by bias, chance or confounding are given. This includes criteria for the choice of an appropriate study design followed by problems of the definition of the study population and the sample selection. We will also point to potential sources of bias in the data collection procedure and list some principles for statistical analysis. Finally, we include comments on how the results should be presented and issues which are related to public health and ethical questions. Although it is not usually possible to perform a perfect study and the correct approach to study design and analysis is often highly dependent on specific features of the population and the surroundings, our paper should help to distinguish between weak and strong investigations and papers.

Bias↗
PubMed2001

Helicobacter pylori infection and serum ferritin: A population-based study among 1806 adults in Germany.

OBJECTIVE: Helicobacter pylori may possibly affect the iron metabolism by occult bleeding, impaired absorption of non-hem iron, and by scavenging hem iron or ferritin, as some studies have suggested. The aim of this study was to analyze the association between H. pylori infection and serum ferritin, a marker of the body iron stores. In this analysis, we paid particular attention to the role of dietary iron intake and CagA, an established virulence factor of the agent. METHODS: The analysis is based on a cross-sectional national health and nutrition survey among healthy people in Germany conducted in 1987/1988. The examination included a detailed questionnaire on medical history and lifestyle factors, a 7-day food record, and blood samples. Infection with H. pylori was measured serologically by ELISA and Westernblot. RESULTS: In total, 39.2% of 1806 persons aged 18 to 89 yr included in the study were H. pylori positive, of whom 57.6% had an infection with a CagA-positive H. pylori strain. Age- and sex-adjusted geometric mean of ferritin was 54.5 microg/dl among H. pylori-infected compared with 63.8 microg/dl among uninfected persons. A multiple linear regression model with log-transformed serum ferritin concentration as dependent variable and H. pylori infection and several potential confounding factors as independent variable was fitted. In this model, H. pylori infection was associated with a 17.0% decrease of the serum ferritin concentration (95% CI = 9.8-23.6). The association between H. pylori infection and serum ferritin levels did not vary by gender, age, and iron intake, and it was similar for CagA-positive and CagA-negative H. pylori infections. CONCLUSIONS: The decreased serum ferritin concentration among subjects infected with H. pylori might be induced by the uptake of ferritin in the stomach by H. pylori. Possible health implications of H. pylori-induced low ferritin levels warrant further investigation.

Adolescent↗
PubMed2001

ISCB-GMDS-99.

Explore the source record for details and available documents.

Biometry↗
PubMed2000

Familial associations of lipid profiles: a generalized estimating equations approach.

Elevated plasma levels of apolipoproteins A1 (apoA1) and B (apoB) are important protective factors and risk factors, respectively, for atherosclerosis and coronary heart disease. It is well known that both apoA1 and apoB reveal strong familial aggregation. Our goal was to investigate whether exogenous variables influence these associations. We used marginal regression models for the mean and association structure (generalized estimating equations 2; GEE2) to analyse data from 1435 family members within 469 families of different sizes included in the Donolo-Tel Aviv Three-Generation Offspring Study. The usual robust variance matrix was approximated by extensions of jack-knife estimators of variance to GEE2 models. Estimation of standard errors in models with quite complex correlation structures was possible using this approach. All analyses were easily carried out using a menu-driven stand-alone software tool for marginal regression modelling. We demonstrate that a variety of hypotheses can be tested using Wald statistics by modelling regression matrices for the association structure. We show that correlation for apoB between parent-offspring pairs increased with decreasing age difference and that pairs with individuals of the same gender had more similar apoA1 levels than individuals of different gender. Associations between different relative pairs did not all agree with those expected from differences in kinship coefficients. The analysis using GEE2 models revealed structures that would not have been detected by other models and should therefore be used in addition to traditional approaches of analysing family data. GEE2 should be considered a standard method for the investigation of familial aggregation.

Apolipoproteins A↗
PubMed2000

Comparing different methods of estimating cosmic radiation exposure of airline personnel.

In Europe, several studies are currently underway to investigate the cancer risk of pilots and cabin crew exposed to low-level ionizing radiation of cosmic origin. Although no individualized exposure measurements of airline personnel are available, exposure assessment based on job history data is feasible. However, there is a marked variability in the level of detail of these data between studies in different countries and between subcohorts in national studies raising the issue of comparability of exposure estimation. In this paper we investigate the comparability of several methods of exposure assessment in a large German cohort of pilots and cabin crew. We found that the correlation between the estimates obtained by the four approaches analysed, is relatively high, ranging from 0.85 to 0.97. The precision attainable in the exposure assessment is higher than in many other epidemiological studies but can be refined further with simulation studies and comparison with ongoing and future on-board measurement programmes.

Aircraft↗