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PubMed2004

A pilot study on the application of statistical classification procedures to molecular epidemiological data.

The development of new statistical methods for use in molecular epidemiology comprises the building and application of appropriate classification rules. The aim of this study was to assess various classification methods that can potentially handle genetic interactions. A data set comprising genotypes at 25 single nucleotide polymorphic (SNP) loci from 518 breast cancer cases and 586 age-matched population-based controls from the GENICA study was used to built a classification rule with the discrimination methods SVM (support vector machine), CART (classification and regression tree), Bagging, Random Forest, LogitBoost and k nearest neighbours (kNN). A blind pilot analysis of the genotypic data set was a first approach to obtain an impression of the statistical structure of the data. Furthermore, this analysis was performed to explore classification methods that may be applied to molecular-epidemiological evaluation. The results showed that all blindly applied classification methods had a slightly smaller misclassification rate than a random classification. The findings, nevertheless, suggest that SNP data might be useful for the classification of individuals into categories of high or low risk of diseases.

Breast Neoplasms↗
PubMed1993

[Do sex steroids cause breast and genital cancers? Epidemiologic data--the current status (July 1993)].

Present literature on epidemiology shows, that estrogens administered either in the form of contraceptives or as replacement therapy will reduce the relative risk of ovarian carcinoma to less than 0.5. Likewise this result was also seen in all studies without exception. The reduction becomes manifest after four months and is maintained for many years following discontinuation. The same applies to corpus carcinoma, provided estrogens are administered concomitantly with gestagens. Administration of estrogens alone results in enhancing the relative risk up to 3-4. Hyperproliferation can lead to carcinoma of the endometrium. No data are presently available for cervical carcinoma, that would justify the assumption, that the relative risk for squamous cell carcinoma of the cervix is increased. This statement does not apply to the adenocarcinoma of the cervix, since too few cases have been studied. The following statements apply to carcinoma of the breast: OC's (oral contraceptives) taken before the age of 45 do not increase the relative risk. This is also true of females, for whom a risk factor exists, as for example family case history, period of administration, benign diseases of the breast, use of OC's before the first pregnancy, nulliparity, no breast-feeding. Possible, but not proven is a slight increase in relative risk to 1.3 in females, in whom carcinoma of the breast had been diagnosed before the age of 34. If this increase is accepted, one must likewise expect a decrease in relative risk after the age of 45. A hormonal replacement therapy for up to four years will not increase the relative risk. This applies also to replacement therapy with gestagens, even though only few data are available at present. It has been concluded from the results of some studies, that a slight increase in relative risk to 1.3 is possible after long-term therapy (more than 15 years). However, no causal relationship to cancer of the breast has been established. It has not been claimed so far, that estrogens cause cancer of the breast. Should the slight relative risk increase be confirmed, this would mean, that in a small group of very young females, estrogens may promote the growth of an already existing cancer of the breast.

Adult↗
PubMed2006

Estimating causal effects from epidemiological data.

In ideal randomised experiments, association is causation: association measures can be interpreted as effect measures because randomisation ensures that the exposed and the unexposed are exchangeable. On the other hand, in observational studies, association is not generally causation: association measures cannot be interpreted as effect measures because the exposed and the unexposed are not generally exchangeable. However, observational research is often the only alternative for causal inference. This article reviews a condition that permits the estimation of causal effects from observational data, and two methods -- standardisation and inverse probability weighting -- to estimate population causal effects under that condition. For simplicity, the main description is restricted to dichotomous variables and assumes that no random error attributable to sampling variability exists. The appendix provides a generalisation of inverse probability weighting.

Causality↗
PubMed2002

[Epidemiological data and radiation risk estimates].

The results of several major epidemiology studies on populations with particular exposure to ionizing radiation should become available during the first years of the 21(st) century. These studies are expected to provide answers to a number of questions concerning public health and radiation protection. Most of the populations concerned were accidentally exposed to radiation in ex-USSR or elsewhere or in a nuclear industrial context. The results will complete and test information on risk coming from studies among survivors of the Hiroshima and Nagasaki atomic bombs, particularly studies on the effects of low dose exposure and prolonged low-dose exposure, of different types of radiation, and environmental and host-related factors which could modify the risk of radiation-induced effects. These studies are thus important to assess the currently accepted scientific evidence on radiation protection for workers and the general population. In addition, supplementary information on radiation protection could be provided by formal comparisons and analyses combining data from populations with different types of exposure. Finally, in order to provide pertinent information for public health and radiation protection, future epidemiology studies should be targeted and designed to answer specific questions, concerning, for example, the risk for specific populations (children, patients, people with genetic predisposition). An integrated approach, combining epidemiology and studies on the mechanisms of radiation induction should provide particularly pertinent information.

Adult↗
PubMedDate not supplied

[Our experience with renal adenocarcinoma (I): epidemiologic data].

OBJECTIVES: The present study was conducted to review the epidemiological factors of patients with renal cell carcinoma. METHODS: We reviewed the familial, social, cultural, toxic, occupational and pathological factors of 229 patients who were diagnosed as having renal cell carcinoma between 1975 and 1992 at our hospital. RESULTS: As in other series, we found a greater predisposition in male patients around the seventh decade. However, unlike other studies, we observed a greater predisposition in the lower social and cultural levels and rural population. Of the epidemiological factors related to adenocarcinoma of the kidney, smoking was the most common in this series (41.8%), followed by high blood pressure (15.7%) and toxic-occupational factors (8.2%). We found no correlation between these factors and tumor stage or survival. CONCLUSIONS: Our data show a greater predisposition for renal cell carcinoma in male patients, around the seventh decade, in the lower social and cultural levels and rural population. Smoking, high blood pressure and occupational exposure to toxic agents were the most common epidemiological factors.

Adenocarcinoma↗
PubMed2005

Scaled rectangle diagrams can be used to visualize clinical and epidemiological data.

OBJECTIVE: To illustrate scaled rectangle diagrams as a method for displaying clinical and epidemiological attributes (such as symptoms, signs, results of marker tests, disease, or risk factors). These are quantitative Venn diagrams, but using rectangles instead of circles. STUDY DESIGN AND SETTING: The method is illustrated through examples from various data sets with different types of clinical information. RESULTS: Examples drawing on studies of lung disease, rheumatic fever, blood pressure, lipid levels, sudden infant death syndrome, and low birth weight illustrate the different types of relationships between variables that the scaled rectangle approach can reveal (e.g., high- and low-risk groups; dependent, independent, or co-occurring attributes; effects from choice of cutoff; cumulative distributions; and case-control attributes). CONCLUSION: Scaled rectangle diagrams are a novel way to display clinical data. They show clearly the relative frequency of clinical attributes and the extent to which they are shared characteristics. Features are revealed that might otherwise not have been appreciated.

Case-Control Studies↗
PubMedDate not supplied

[Pulmonary Tbc in the 90's in Taranto and province (epidemiological data)].

We have reported the results of a clinical and epidemiological study on the cases of the tuberculosis of the lung observed in two years (1988-1989) and in the first half of the 1990 in Taranto and in the district of Taranto. The data obtained show the incidence of tuberculosis is enough high today.

Adolescent↗
PubMed2004

Tick-borne encephalitis (TBE) in Germany--epidemiological data, development of risk areas and virus prevalence in field-collected ticks and in ticks removed from humans.

In Germany, 100-300 autochthonous clinical TBE cases have been recorded annually. There are high-risk areas in Bavaria and Baden-Wuerttemberg and ongoing low-risk areas in Hesse, Thuringia, and the Rhineland-Palatinate and single cases in Saxony. In order to be able to evaluate the epidemiological changes described here, it must be mentioned that a new definition of TBE risk areas was introduced on the district level in 1998 in Germany and in 2001 with the new Infection Protection Act (Infektionsschutzgesetz) which states that TBE is a notifiable disease. This led to the replacement of earlier surveillance systems and to many changes to data collection. In 1998 63 country and town districts were TBE risk areas, in 2001 79 and in 2002 86. There were new risk districts within Bavaria and Baden-Wuerttemberg and outside these regions in Thuringia, Hesse and the Rhineland-Palatinate. An interesting trend was observed in TBE epidemiology. The TBE incidence in Bavaria and Baden-Wuerttemberg has been stable on a high level for years; outside these areas it has steadily been climbing (Odenwald, Thuringia). On the basis of epidemiological data on TBE from the eastern part of Germany since 1960, it is obvious that major changes in virus activity in TBE risk areas also occurred in the past, the explanation of which has remained a matter for speculation. The epidemiological situation in the different risk areas for TBE in Germany was found to vary considerably, if one considers the surveillance data of the last 40 years. 1. Establishment of completely new low-risk areas. 2. Reactivation of formerly active areas with endemic latency. 3. High-risk areas with stable viral activity over long periods. 4. High-risk areas which have expanded and merged with low-risk areas. 5. High-risk areas which have developed into endemic areas or become inactive. High-risk TBE areas from 1960-1975 (i.e. Mecklenburg-Western Pomerania) have since completely disappeared. There were, at the same time, high-risk areas in Thuringia which had only become latent and have now obviously become active again. The Odenwald demonstrated growing virus activity in the 1990s. These changes in TBE activity in German risk areas over more than the last 40 years are presented schematically. This ongoing number of risk areas is certainly linked to the notification obligation and greater public awareness. Nevertheless, any effects of ecological and climatic changes on the natural foci cannot be ruled out nor can changes in human leisure behaviour. Local weather conditions also have a major effect on the TBE incidence. Warm and dry summers may cause low tick activities, rainy summers may lead to low exposure rates of human beings. Even changes in forms of agricultural production prompted by different political structures probably have an impact as do economic constraints which may lead to lower vaccination and higher exposure rates. Regular, systematic virus prevalence measurements from 1997 to 2002 in field-collected ticks in German high-risk areas do not indicate any risk increase nor do they suggest a downward trend. Studies on virus prevalence in questing versus partially engorged ticks indicate that we neither exactly know nor understand the real quantitative relations between the virus and the host. In a first study, virus prevalence in Ixodes ricinus removed from humans was examined. Humans which were exposed in some districts near Passau in Bavaria. In the autumn of 2001, virus prevalence of unengorged free-living nymphs (n = 820) in this area was 0.38 (0.08-1.1)% and of adults (n = 90) 1.17 (0.03-6.38)%. Surprisingly, virus prevalence in partially engorged ticks from the same area collected during the same period was significantly higher (nymphs, n = 86, 6.9% and adults, n = 129, 9.3%). Virus-positive partially engorged ticks were only found in districts known as risk areas. Nucleotide and deduced amino acid sequence data of the PCR products have confirmed the presence of virus prototype Neudoerfl only.

Animals↗
PubMed1993

The quality of epidemiological data in coronary heart disease and atherosclerosis.

There are inherent difficulties in the use of indirect observations in the epidemiology of a chronic ubiquitous disease such as atherosclerosis. Such difficulties do not condone basic errors in epidemiological methodology, the use of low quality data, a lack of precision in measurements, invalid extrapolations and inappropriate use of terminology and coronary heart disease as a surrogate or synonym of coronary atherosclerosis and bias in the interpretation of data. These errors reveal a lack of rigorous and scientific standards in the epidemiology of coronary heart disease. Analysis cannot launder such data. Independent scientists must evaluate the data in respect of precision, logic and truth.

Arteriosclerosis↗
PubMed1987

Problems with the interpretation of epidemiological data in heartwater: a study on 23 farms.

In an epidemiological study undertaken on 23 farms where heartwater occurs endemically, it was found that on an overall average, antibodies to Cowdria ruminantium were detected in 64.3% of the cattle, 6 adult Amblyomma hebraeum ticks were counted per animal and 7.0% of ticks were infected with the heartwater agent. It was found that the seropositivity of the animals was determined largely by the tick loads to which they were subjected and that the influence of the tick C. ruminantium infection rate was less evident. There was no parallel between the prevalence of heartwater on the farms and the immune status of the animals. In general, higher tick counts were recorded in herds where strategic tick control is practised than on farms with a total tick control programme. The method of tick control did not, however, appear to influence the immune status of the cattle, the tick infection rate, or the prevalence of heartwater.

Animals↗
PubMed1998

Epidemiological data in polycythaemia vera: a study of 842 cases.

An epidemiological study of 842 polycythaemic patients (entered between 1980 and 1997 in the French investigational prospective protocols) is presented. The global incidence is approximately 0.8-1.5/100,000/year in the reference area (Ile-de-France and surrounding areas). It increases linearly with age until 80, which suggests that several mutational somatic events are necessary. There was a slight male excess (sex-ratio 1.2, after correction for the percentage of male and female French people still living at risk). We did observe a slight excess of PV in the population of Jewish ancestry. A surprising excess of former blood donors (20.7% of the PV cases, compared to 8% estimated in the reference population) was observed. Only a few cases of familial myeloproliferative diseases and occurence of leukemia in the family of our patients have been observed; even if slight, this excess is statistically significant. In contrast, no excess of carcinomas was observed either in the family or in the patients' antecedents. We did not find any excess of radiation exposure in our cases. When analysing the previous occupation of our patients a possible excess of physicians and of patients previously working in occupations using solvents and glues was found, but this finding needs confirmation.

Adhesives↗
PubMed2000

Comparison of protein A gene sequencing with pulsed-field gel electrophoresis and epidemiologic data for molecular typing of methicillin-resistant Staphylococcus aureus.

The epidemiologic relatedness of methicillin-resistant Staphylococcus aureus (MRSA) isolates is currently determined by analysis of chromosomal DNA restriction patterns by pulsed-field gel electrophoresis (PFGE). We have evaluated an alternative typing system (MicroSeq StaphTrack Kit; Perkin-Elmer Biosystems) based on the sequence analysis of the chromosomally encoded polymorphic repeat X region of the S. aureus protein A (spa) gene. A total of 69 clinical MRSA isolates were divided into 18 groups according to the number and nucleotide sequences of the spa repeats. Molecular typing results obtained both by spa sequencing and from the PFGE patterns were concordant except for one group, which contained 20 isolates recovered over a 2-year period from hospitalized patients at the Mayo Clinic. Although the spa typing patterns were indistinguishable for those isolates, PFGE analysis yielded seven related but distinguishable patterns. Further coagulase gene sequence analysis subtyped those 20 strains into four groups which followed distinct temporal and geographic distributions. During a 2-year epidemic period there were up to 7 fragment changes in PFGE patterns among epidemiologically related isolates, suggesting that PFGE may be unsuitable for long-term typing of strains involved in epidemics. Although more limited than PFGE in discriminatory power, spa sequencing analysis could be used as a screening method for typing of MRSA strains because of the shorter turnaround time, ease of use, and the inherent advantages of sequence analysis, storage, and sharing of information.

Animals↗
PubMed2000

[Bacteriological and epidemiological data on Streptococcus pneumoniae in the hospital of southern Reunion Island].

We studied the epidemiology of Streptococcus pneumoniae in southern Reunion Island from 1993 to 1998. Data were collected from the Centre hospitalier Sud Reunion. Incidence of pneumonia was calculated by applying published ratios to two different types of data (bacteriological, clinical). Survey of pneumococci showed that antimicrobial resistance of S. pneumoniae to penicillin G appeared in 1994 and reached high levels in 1998. We confirmed the increase of multiresistant strains among penicillin resistant S. pneumoniae. Serotyping the penicillin resistant S. pneumoniae has shown that these strains belonged to serogroups 9, 14, 19, 23. The MIC determined in PRP showed that imipenem was the most active agent among beta-lactamin antibiotics followed by ceftriaxone. Strains with high resistance to amoxicillin are rare. Annual incidence of meningitis was almost 0.4 per 100,000 inhabitants. Estimation of pneumonia incidence was between 44 and 78 per 100,000 inhabitants. Incidence in Reunion Island is twice to three times lower than the incidence in France. Death rate from pneumoniae (10%) is similar to that in France. In the course of the study, the number of isolated S. pneumoniae increased. Changing socio-economic conditions are probably associated with the emergence of PRP since 1994 and the increase in numbers of infections. Pneumococcal infections in Reunion Island are becoming a public health problem of the same importance as in France.

Adolescent↗
PubMed1995

Critical assessment of the epidemiological data concerning the impact of antioxidant nutrients on cancer and cardiovascular disease.

Epidemiological studies strongly suggest that high intakes of foods rich in beta carotene, as well as those rich in vitamin E or vitamin C, reduce the risk of some but not all cancers and cardiovascular disease. It is difficult to determine whether these antioxidant nutrients per se are the sole protective agents or whether other factors associated with foods containing them contribute to the foods' protective effects. With respect to vitamin E, a number of studies where dietary and supplementary vitamin E were clearly differentiated, a reduced risk of certain cancers or cardiovascular disease from supplemental vitamin E but not from dietary vitamin E was demonstrated. This provides strong presumptive evidence that high intakes of vitamin E per se provide a health benefit. Only a few intervention studies with specific nutrients are available and results are inconsistent.

Antioxidants↗