Biomedical subjects

J Bouyer

Publications and source records attributed to J Bouyer.

At least 55 records · Page 3Linked to original sources

PubMed1996

[Epidemiology of ectopic pregnancy: incidence and risk factors].

During the past two decades, the incidence of ectopic pregnancy (EP) has doubled or tripled in many parts of the world. In France, EP currently constitutes 2 % of livebirths and 1.6 % of all reported pregnancies. These rates seem presently stable. The main identified risk factors include pelvic inflammatory disease (PID)--in particular that due to Chlamydial infection, previous ectopic pregnancy and cigarette smoking. More than 50 % of EP cases are attributable to infectious factors and cigarette smoking, suggesting dramatic effects on EP rates of appropriate prevention programs. A third risk which could be prevented is induced conception cycles, especially by Clomiphene. Other risk factors are pelvic surgery, previous EP and maternal age (especially over 35 years). Further epidemiologic research is needed to identify new risk factors, to monitor incidence rates and to evaluate the effects of public health policies on EP occurrence. French EP registers will certainly contribute to this research.

Female↗

PubMed1996

[Ectopic pregnancy: factors related to ovum anomalies?].

Identified risk factors for ectopic pregnancy (prior pelvic inflammatory disease, smoking at the time of conception, intrauterine device, obstetrical and surgical history) explain from 60 to 65% of the cases. Egg anomalies may also be a risk factor as it is likely that the transport of an abnormal egg along the uterine tube is less efficient than a normal one. We tested this hypothesis with data from two case-control studies with the same design covering a total of 1955 women. The risk of ectopic pregnancy increased specifically with age, which is compatible with our hypothesis. We also studied the associations with spontaneous abortion, considered to be a marker of the risk of pregnancies involving chromosomal malformations. We observed an association between ectopic pregnancy and spontaneous abortions (especially recurrent abortions), not explained by other known risk factors. Although our data do not supply a single definitive demonstration, our results converge to suggest that egg chromosomal anomalies may play a part in ectopic pregnancy aetiology.

Abortion, Spontaneous↗

PubMed1996

[Fertility after ectopic pregnancy. Results of the first three years of the Auvergne Registry].

The reproductive outcome after ectopic pregnancy is evaluated from a population-based register in the center of France. Since 1992, all the women aged 15-44 years, who permanently reside in the target area and who were treated either by surgical or medical procedures for an ectopic pregnancy in one of the area centers, are registered and prospectively followed until 45 years of age. The analysis presented was based on the 221 women registered between January 1992 and December 1994 who were followed up for at least 6 months, and who were seeking a new pregnancy. The mean follow-up period was 19.8 months. 155 women (70%) obtained a pregnancy. The first conception was intrauterine for 136 women, and 19 had a recurrence of ectopic pregnancy. Risk factors of recurrence were prior spontaneous abortion and prior tubal damage. For those women who conceived, the mean time to obtain pregnancy ("time to pregnancy") was 7.6 months. The one year cumulative intrauterine pregnancy rate (i.e. the probability of obtaining an intrauterine pregnancy within 1 year of seeking pregnancy) was 64%. After multivariate analysis by a Cox regression, the factors associated with lower fertility were aged over 30 years, low educational level, history of infertility and prior tubal damage.

Adolescent↗

PubMed1995

[Incidence of extra-uterine pregnancy and characteristics of treated patients. First results of the Auvergne registry].

OBJECTIVES: To evaluate the course and frequency of ectopic pregnancy in a single population for a prolonged period in order to study the simultaneous changes in distribution of risk factors, identify new risk factors and evaluate the effect of new diagnostic and therapeutic methods on subsequent fertility and the effectiveness of preventive measures. METHODS: All women residing in the Registry zone and treated surgically or medically for ectopic pregnancy were included in the study and followed to the age of 45 years. RESULTS: In 1992, the incidence of ectopic pregnancy was 20.2 per 1,000 live births (n = 160). At least one currently recognized risk factor was found in 80% of the women. A past history of salpingitis was noted in 13% and nearly one half smoked or had smoked at the time of conception. Nineteen percent had a past history of pelvic surgery and 19% had a history of infertility. The ectopic pregnancy recorded was the second one in 9%. Nearly one-third of the ectopic pregnancies recorded (31%) were diagnosed in patients with a intrauterine device. None of these latter patients had other risk factors. Vaginal echography was used for diagnosis in 75% of the cases. Surgery was used as first intention treatment in 94% and medical treatment (methotrexate) was used in 6%.

Adult↗

PubMed1995

Performance of odds ratios obtained with a job-exposure matrix and individual exposure assessment with special reference to misclassification errors.

OBJECTIVES: Individual assessment of exposure by experts and the use of a job-exposure matrix are the two main methods of evaluating past occupational exposures in community-based case-referent studies. The objective of this study was to compare the performance of the estimations of the odds ratio in the two methods. This paper focuses on job-exposure matrices whose entries consist of proportions of persons exposed. METHODS: Simulations were used to compare the variances of the estimations of the odds ratios obtained with the two methods and to study the consequences with respect to bias and the precision of the odds ratios estimated for misclassifications of exposure produced by either the experts or the matrix. RESULTS: When there was no misclassification, the results showed that the precision obtained with the job-exposure matrix was about three times less than that achieved by experts in a large range of practical situations. However, when potential errors of exposure assessment were taken into account, the simulations suggested that the test of the hypothesis OR = 1 against the alternative OR not equal to 1 when exposure was assessed with an unbiased job-exposure matrix had a statistical power close to that obtained when exposure was assessed by an expert with high sensibility and specificity. CONCLUSIONS: The evaluation of exposure with an unbiased job-exposure matrix in studies of the association between exposure and disease had a statistical power close to that expected in practice with a good expert in the large range of practical situations which were investigated.

Bias↗

PubMed1994

[Job exposure matrices].

During the last years, the use of Job Exposure Matrices (JEMs) for the evaluation of past occupational exposures has grown. This approach is described in this paper. The definition of a JEM is provided. The development process of a JEM is discussed. It includes the choice of the job classification system which influences the degree to which the matrix can be used in other studies, the precise definition of exposures and the choice of entries which should provide more information than the oversimplified exposed/non exposed dichotomy. When comparing JEMs and experts' evaluation of exposure, all aspects of both methods have to be looked at and a balance struck between the advantages and shortcomings of each of them. The problem should not be reduced to a single choice between the precision provided by experts, and the cost savings and standardization offered by JEMs. Statistical analysis with a JEM must be adapted to the job classified information it provided. When an appropriate method is used, the loss of power with a JEM compared to experts' evaluation is rather small or even null. Finally, it is important to avoid a systematic opposition between JEMs and expert assessments, as one positive result of their comparison may be the improvement of both methods of exposure evaluation.

Biometry↗

PubMed1993

Comparison of three methods of estimating odds ratios from a job exposure matrix in occupational case-control studies.

A job exposure matrix consists of jobs on one axis and substances on the other, with the matrix elements describing the likelihood of an individual's exposure to a substance in a given job. This can be used in case-control studies to infer exposures of subjects whose jobs are known. The simplest form of job exposure matrix contains binary entries, but it is also possible to envisage continuous variables describing the probability of exposure in the job (probabilistic matrix). In such a case, the user has various options for transforming and analyzing the data, including the following: 1) transform to binary variables and analyze as conventional binary exposure variables; 2) leave as continuous variables and analyze using logistic regression; 3) leave as continuous variables and analyze using a linear model. Simulations were carried out to compare the ability of the three methods to estimate odds ratios under 36 experimental conditions. The linear model produced unbiased estimates, the logistic model produced somewhat biased estimates at high odds ratios, and the transformation to a binary variable produced systematically low estimates in most experimental circumstances. With the linear and logistic models, the odds ratio estimators had similar precision when the bias of the latter was not too great. The authors conclude that the linear model permits optimal use of a probabilistic matrix in an epidemiologic study and hope that these results will encourage the development of job exposure matrices containing probabilities rather than dichotomies.

Case-Control Studies↗

PubMed1993

Retrospective evaluation of the exposure to polycyclic aromatic hydrocarbons: comparative assessments with a job exposure matrix and by experts in industrial hygiene.

This work aimed at assessing the validity of job exposure matrix (JEM) for the retrospective evaluation of exposure to polycyclic aromatic hydrocarbons (PAH) within the framework of population-based case-control studies, taking the evaluation of industrial hygiene experts as reference. For this purpose, we used a case-control study for which the different levels of exposure were assessed by such experts after case by case evaluation of all job periods reported by the subjects. The JEM was applied to this set of data so that we had, according to job periods, the experts' evaluation on the one hand, and the JEM evaluation on the other. JEM sensitivity and specificity of the matrix vary widely from 0.13 to 0.96 and 0.58 to 0.99 respectively, depending on whether the experts chose a narrow or wide definition of exposure and on the cutoff point chosen to dichotomize the JEM. We also computed, according to the sensitivity and specificity of the JEM, the odds ratio (OR) and relative efficiency (RE) given by the JEM for several hypothetical OR and frequencies of exposure among the controls. These calculations were made for different definitions of exposure by the experts and different cutoff points for the JEM. The results show a bias in the JEM's evaluation of the OR. In addition, the RE varies widely from very low values to high values (0.05-0.45) depending on the experts' definition of exposure and the cutoff point chosen for the matrix. Note, however, that all these calculations were made taking the experts' evaluation as the reference.(ABSTRACT TRUNCATED AT 250 WORDS)

Case-Control Studies↗

PubMed1993

Retrospective evaluation of occupational exposures in population-based case-control studies: general overview with special attention to job exposure matrices.

Different approaches may be considered in the evaluation of past occupational exposures: questionnaires only, questionnaires and experts (such as industrial hygienists or occupational physicians), questionnaires and job exposure matrices (JEM). These approaches are described in this paper and their use in the framework of population-based case-control studies is discussed. The use of experts to assess exposure from questionnaires is generally considered to be the reference method. Its major drawbacks are its cost and the shortage of experienced experts. On the other hand, JEM reduce the cost of the study and provide an objective way of evaluating exposures. The main drawback of JEM is the fact that they can produce misclassification. The development of a JEM includes the choice of the job classification system which influences the degree to which the matrix can be used in other studies, the precise definition of exposures, and the choice of entries which provide more information than the oversimplified exposed/non-exposed dichotomy. Recent results on JEM methodology (statistical methods of analysis and evaluation of JEM quality) should encourage both their development and their use in epidemiological studies.

Case-Control Studies↗

PubMed1993

Studying the performance of a job exposure matrix.

During the last decade, the use of job exposure matrices (JEM) in occupational studies has grown but uncertainty remains among epidemiologists and industrial hygienists regarding this methodology and appropriate methodological tools are needed to study the performance of JEM. It must first be emphasized that a true validation can rarely be achieved and that the performance of a JEM must be tested against the exposure evaluation of another method taken as a reference, such as expert assessment. This comparison comprises three main elements: the ability of the JEM to evaluate accurately the exposure itself, its statistical performances in terms of bias and power and its ability to detect known associations between risk factors and disease. When comparing JEM and experts, all aspects of the two methods have to be looked at and a balance struck between the advantages and shortcomings of each of them. The problem should not be reduced to a trade-off between the precision provided by experts and the cost savings possible by using JEM. Finally, it is important to avoid a systematic opposition between JEM and expert assessments, as one positive result of their comparison may be the improvement of both methods of exposure evaluation.

Bias↗

PubMed1993

Retrospective evaluation of occupational exposure to organic solvents: questionnaire and job exposure matrix.

Correct retrospective assignment of subjects to an exposure category is affected by a variety of problems: 1) lack of an objective lifetime measurement; 2) dependence upon the accuracy and thoroughness of the job description; 3) heavy reliance upon the knowledge of experts. The aim of the study was the quantification of the performance of a job exposure matrix (JEM) in evaluating solvent exposure, using expert judgements as the reference method. The sources of discrepancies between the two methods were analysed within the framework of two community-based case-control surveys. One included 765 cases of bladder cancer (BC) and 765 controls, the other 298 cases of glomerulonephritis (GN) and 298 controls. The JEM had been set up previously for a case-control study on laryngeal cancer and is based on 4000 discrete job titles. Comparison between the JEM and expert exposure evaluation was carried out for 2736 job periods in the BC study and 929 in the GN study. Categories of exposure for both experts and JEM were dichotomized, using different cutoff points for exposure and non-exposure. Prevalence of exposure as assessed by the experts was twice as high in the GN study (19%) as in the BC study (10%), showing the importance of the questionnaire design and of the inclusiveness of the definition of exposure. Sensitivity of the JEM vis-a-vis the experts was low (23-63%), whereas specificity was rather high (87-98%). The best concordance between the two methods was obtained with a specific dichotomy from the JEM and a narrow definition of exposure by the experts. Bias and loss of power resulting from JEM misclassifications were calculated with a theoretical population odds ratio of 3 and an exposure prevalence of 10%. If the experts' classification of the subjects according to exposure is assumed to be 100% correct, using the JEM led to a bias in estimating the odds ratio, ranging from 1.5 to 2.1, and to a loss of power equivalent to a reduction in the number of subjects by a factor of 5 to 10. Analysis of systematic discrepancies between exposure assessments of the experts and the JEM showed that they were clustered with some job categories and arose from different sources: 1) inadequate job descriptions, related to the codification system adopted and necessitating the gathering of information at the individual level; 2) true disagreements between JEM and experts regarding the definition of solvent exposure.(ABSTRACT TRUNCATED AT 400 WORDS)

Case-Control Studies↗

PubMed1993

Risk factors for death in meningococcal disease.

Of 2.139 cases of meningococcal infections notified in France from 1985 to 1989, 10% died. The risk factors for death and for purpura fulminans (extensive purpuric rash associated with cardiovascular collapsus) were studied using multifactorial analysis. The purpura fulminans was the major risk factor for death (representing 22% of the cases and 77% of the deaths in our study). In the absence of purpura fulminans, significant risk factors for death were: serogroup A or infrequent serogroup infection, an age over 50 years, and the occurrence of a septicaemia. In the presence of purpura fulminans, significant risk factors for death were an age under one year or over 10 years, and an infection with negative cultures from blood and cerebrospinal fluid. The main risk factor for purpura fulminans was the occurrence of septicaemia. Purpura fulminans appears to be a simple and specific clinical entity reflecting the high level of endotoxin released during meningococcal septicaemia.

Adolescent↗

PubMed1991

Vaginal infections, cervical ripening and preterm delivery.

A prospective study is presented which addresses the relative effect of cervicovaginal infection and precocious maturation of the uterine cervix on preterm delivery. From April 1981 through December 1983, a total of 5758 pregnant women were checked by means of a vaginal examination at every prenatal visit and a research for bacterial cervicovaginal infection whenever abnormal signs were observed. The study reveals that vaginal infection has no measurable effect when observed during the second trimester of pregnancy, and a small effect during the third trimester. This means that infection of the vagina or/and the cervix may be demonstrated as a risk factor only when the cervix is short before 28 weeks or open before 37 weeks.

Bacterial Infections↗

PubMed1991

Prevention of sexually transmitted diseases: a randomised community trial.

STUDY OBJECTIVE: The aim was to evaluate the effectiveness of a programme for the prevention of sexually transmitted diseases which affect fertility. DESIGN OF THE PREVENTION PROGRAMME: The programme took place in six French geographical departments. Three of these, randomly selected, served as experimental departments while the other three were matched with the first three and served as controls. DESIGN OF THE EVALUATION: Genital discharge was used as the indicator of a sexually transmitted disease. In each department, about 40 voluntarily participating general practitioners (263 in total) gathered information on the frequency of infected patients and on their characteristics, both before and after the campaign. PATIENTS: Before and after the programme respectively, 412 and 288 women and 117 and 94 men with a genital discharge were described. MEASUREMENTS AND MAIN RESULTS: After the programme, tests for chlamydia trachomatis were prescribed more often to both women and men with a discharge in the experimental departments. The characteristics of women having consulted a general practitioner with a discharge differed according to the department group studied. In the experimental departments, the women were younger than those in the control departments and had fewer sexual partners. In contrast to the results obtained for women, no behavioural changes were observed among men with a discharge. CONCLUSIONS: The results may indicate a decreased risk in spread of infection. Methodological problems associated with such a design are discussed. There is a need to develop specific messages aimed at changing male sexual behaviour. The study design has implications for the best strategy in delivering prevention messages to the general population which are relevant to the present AIDS epidemic.

Adolescent↗

PubMed1991

[Logistics regression in epidemiology. II].

The logistic regression is used in epidemiology to study the relationships between a disease in two modalities (diseased or disease free) and risk factors Xi which may be qualitative as quantitative variables. According to this model, the probability of disease knowing Xi's values is written: [formula: see text]. The coefficients satisfy to the equation: ORi = exp(beta i) where ORi is the odds-ratio linked to the variable Xi adjusted on the other variables of the model. The second part of this paper is devoted to the tests of hypothesis in the logistic model and to the choice of the variables to be included in the model. The way of using tests to decide how to code variables is explained. Analysis strategy (choice and selection of variables) is discussed. The rational of goodness of fit tests is shown. At least, we indicate how to use the logistic model in case-controls studies and in studies with matched samples.

Case-Control Studies↗

PubMed1991

[Epidemiological methods in evaluation].

This paper describes different epidemiological methods to evaluate the effect of a public health intervention. The different types of indicators as well as types of evaluative surveys (experimental, quasi-experimental, observational) are presented. Criteria for choosing one type of survey are discussed. Examples of surveys are described.

Cohort Studies↗

PubMed1991

[Logistic regression and epidemiology. I].

The logistic regression is used in epidemiology to study the relationships between a disease in two modalities (diseased or disease free) and risk factors Xi which may be qualitative or quantitative variables. According to this model, the probability of disease knowing Xi's values is written: [formula: see text]. The coefficients beta i satisfy to the equation: ORi = exp(beta i) where ORi is the odds-ratio linked to the variable Xi adjusted on the other variables of the model. The first part of this paper indicates the way to include in the model qualitative variables with more than two modalities, quantitative variables and interaction between variables. At least, the maximum likelihood method to estimate the parameters of the model is presented.

Epidemiologic Methods↗

PubMed1989

[Attempted analysis of the progressive development of prematurity between 1980 and 1985 at the maternity hospital in Haguenau].

The recent increase of premature births has led the authors to conduct an exhaustive, prospective investigation from computerized data, including 8,618 pregnant women who delivered at the Maternity Hospital in Haguenau between January 1980 and December 1985. Their results disclose a significantly increased ratio of premature births in the gravida I group and in women with a primary level of education, who were followed by a general practitioner. On the other hand, the ratio of premature births at 34 weeks and less, is also increased in people followed by a general practitioner, which is not the case for induced prematurity. These results, although preliminary, prompt the consultant to reconsider primary prevention in these groups with particular risks.

France↗