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B Laumon

Publications and source records attributed to B Laumon.

At least 19 recordsLinked to original sources
PubMed2005

Modelling the hierarchical structure of road crash data--application to severity analysis.

Road crashes have an unquestionably hierarchical crash-car-occupant structure. Multilevel models are used with correlated data, but their application to crash data can be difficult. The number of sub-clusters per cluster is small, with less than two cars per crash and less than two occupants per car, whereas the number of clusters can be high, with several hundred/thousand crashes. Application of the Monte-Carlo method on observed and simulated French road crash data between 1996 and 2000 allows comparing estimations produced by multilevel logistic models (MLM), Generalized Estimating Equation models (GEE) and logistic models (LM). On the strength of a bias study, MLM is the most efficient model while both GEE and LM underestimate parameters and confidence intervals. MLM is used as a marginal model and not as a random-effect model, i.e. only fixed effects are taken into account. Random effects allow adjusting risks on the hierarchical structure, conferring an interpretative advantage to MLM over GEE. Nevertheless, great care is needed for data coding and quite a high number of crashes are necessary in order to avoid problems and errors with estimates and estimate processes. On balance, MLM must be used when the number of vehicles per crash or the number of occupants per vehicle is high, when the LM results are questionable because they are not in line with the literature or finally when the p-values associated to risk measures are close to 5%. In other cases, LM remains a practical analytical tool for modelling crash data.

Accidents, Traffic↗
PubMed2004

[Differences between males and females in traffic accident risk in France].

BACKGROUND: In France 7,720 people were killed in traffic accidents in 2001, 75% of which were men; the number of injured people is estimated at 153,945, of which 65% were men. The objective of the study is to describe differences between males and females regarding accidents, and to explain the main reasons for these differences. METHODS: Analysis is conducted from both national police data (2001) and data from the Rhone medical road accident trauma Register (1996-2001). RESULTS: The male/female incidence rate is 3.1 for mortality (95% CI: 3.0-3.3) and 1.7 for morbidity (95% CI: 1.7-1.8). Two-wheel motorised vehicle accidents are very specific to males, which explains part of this overrepresentation. The fatality rate and the severe injuries rate among survivors are higher for males. This is true for every main user group (car users, motorised two-wheelers, cyclists, pedestrians) after adjusting for accident circumstances and age of casualties. Males are more severely injured for all body regions and have more often severe after-effects. CONCLUSIONS: This paper shows the mechanisms leading to this unfavourable outcome for men. They correspond to differences in the number of trips, in the choice of road transport types, and moreover to differences in risk-taking behaviours. Underlying these behaviours, deep-rooted, strong and rather invariant differences between genders are to be found in the values associated with risk-taking on the road.

Accidents, Traffic↗
PubMed2003

Comparison of road crashes incidence and severity between some French counties.

Our aim is to compare traffic safety among several counties in France, and explore whether observed differences can be explained by differences in road types distribution and by differences in socio-economic characteristics between counties. Traffic safety is measured by incidence and severity, where incidence is defined by the ratio of counts of injury accidents and exposure, measured by the amount of kilometres driven. Severity is measured by the ratio between fatal and injury accidents. These indexes are analysed in the framework of Generalised Linear Models: counts of injury accidents are analysed with a Negative Binomial regression, which accounts for over-dispersion. Severity being the proportion of fatal accidents among injury accidents corresponds to the probability of a Binomial setting and this is modelled by a logistic regression. This modelling provides an easy way to adjust for covariates such as road type, environment (urban/rural) and evolution over time, and to test their possible interactions. We find that the time trend of each indice (incidence and severity) is the same across counties and across road types. There is a significant interaction between county and road type, meaning that, first, differences in traffic safety between counties are not fully explained by different road type distributions, and second, that the "ranking" of counties in term of incidence or severity varies according to the road type considered, and vice-versa. It was planned to explore global characteristics of the counties (driving and socio-economic data) as possible explanatory factors of differences between counties, but the existence of an interaction of county with road types shows the necessity of collecting and exploring characteristics of the sub-levels of road type within county.

Accidents, Traffic↗
PubMed2002

[Analysis of biases in epidemiological knowledge of road accidents in France].

BACKGROUND: In France, as in many countries, road casualty statistics are mostly based on police reports. It is generally recognized that these data are incomplete but no measurement has been made of the degree of under-reporting and thus of associated biases. This study aims to demonstrate and quantify these biases. METHODS: The study compares, after data linkage, the 10,202 people reported injured or killed in 1996 in the medical road accident victims Register in the Département du Rhône (France), with the 4,572 victims reported by the police during the same year and in the same area. This Département was chosen, as it is the only region in France where these two independent data sources coexist. Two types of possible biases are studied: injury severity classification bias and selection bias induced by underreporting. RESULTS: The study shows that the definition of "serious injury" used by the police exaggerates the severity of the victim's condition in over half the cases. This bias depends on road user group. This bias is maximum for pedestrians: compared to a slightly injured car occupant, a pedestrian with the same injury severity level has significantly more chance to be considered as severely injured (RR=1.78; 95% CI: 1.11-2.87). Conversely, significant selection biases are related to data collection by the police. The multivariate analysis shows that the underreporting of victims increases if no third party is involved (i.e. without any other vehicle or pedestrian), and reduces with injury severity. It also varies by road user group (with the largest underreporting for cyclists). Among the most seriously injured in accidents involving third parties, motor cyclists and car users are the most reported category and pedestrians the least (RR=0.80; 95% CI: 0.70-0.92). Biases in Register selection are much more limited and basically concern underreporting of victims of minor accidents who did not require medical care. CONCLUSIONS: This study confirms and quantifies misleading distortions in police statistics used to assess road accidents. These results concern the relevant indicators to be used to define road safety issues.

Accidents, Traffic↗
PubMed1998

[Epidemiologic research and road traffic accidentology in Europe].

Every year there are 1.7 million road casualties on EU roads, of which 46,000 are fatal. With reference to the three main sources of information available (the police, the medical profession, and insurance companies), we have extracted epidemiological results for this important public health issue, taking into account the relevance of this approach in terms of its exhaustiveness and representativity. Finally, referring to different ad hoc etiological and evaluative research, we have put forward some ideas on the possible contribution that epidemiology could make to a better understanding of road traffic accidents. Given that current research is coordinated at an EU level, we have confined our analysis to the 15 member countries of the EU.

Accidents, Traffic↗
PubMed1996

[Fetal growth from the AUDIPOG study. II. Application for the diagnosis of intrauterine growth retardation].

The identification of intrauterine growth retarded infants remains a problem. It is useful to distinguish between small for date which uses the reference of a statistical birthweight limit and intrauterine growth retardation. A study comprising nearly 100,000 births from many French regions allowed a definition of the limits of birthweights taking into account gestational age, sex, birth rank, maternal height and pregravid maternal weight. This new approach distinguished two groups of newborns, the "constitutionaly small" and those who are newly called "growth retarded". The validity of this new classification is discussed.

Adult↗
PubMed1994

Sexually transmitted diseases as major causes of ectopic pregnancy: results from a large case-control study in France.

OBJECTIVE: To evaluate the current impact of sexually transmitted diseases (STDs) and their consequences on the occurrence of ectopic pregnancy (EP). DESIGN: Case-control study. SETTING: Fifteen maternity hospitals in the Rhône-Alpes region, France. SUBJECTS: Six hundred twenty-four women with EP diagnosed from October 1988 to December 1991 and 1,247 controls who delivered liveborn children during the same period. MAIN OUTCOME MEASURES: Information on risk factors included behavioral, clinical, and serological indicators of STDs and other known risk factors of EP. RESULTS: Logistic regression identified several indicators of STDs as strong and independent risk factors for EP: previously treated STD without history of salpingitis; history of probably pelvic inflammatory disease (PID) and, especially, history of confirmed PID; previous STDs of the sexual partner; and Chlamydia trachomatis seropositivity. The adjusted attributable fractions of EP for previous symptomatic STDs, symptomatic STDs of the sexual partner, and C. trachomatis seropositivity were 20%, 3.5%, and 25.2%, respectively, giving a total of 43% of EP cases attributable to infectious factors. CONCLUSIONS: Our findings and previous epidemiological and biological evidence suggest that STD is a major cause of EP. The evidence is particularly strong in the case of C. trachomatis infection. An effective way of dramatically reducing the EP rate would be to prevent STD through education programs sensitizing young women to the complications of STD and public health measures promoting the use of protective methods such as condoms.

Adolescent↗
PubMed1993

Dimensions and form of dental arches in subjects with normal occlusions.

To determine the main mandibular dental arch forms, 278 dental casts of untreated French adults with normal occlusions were examined. Six measurements of the mandibular dental arches were performed, and five independent ratios were determined. By following the k-means clustering method on the basis of these ratios and the use of polynomial functions of the sixth degree, five mandibular dental arch forms were defined, and an arch guide was developed. The proposed forms are relatively narrow in comparison with previous studies. No significant differences in their distributions were seen between male and female subjects. However, the dental arches of the women have smaller dimensions.

Adolescent↗
PubMed1993

[Risk factors for ectopic pregnancy. Results of a case control study in the Rhone-Alpes region].

A case-control study was conducted in 14 Rhône-Alpes area (France) maternity hospitals to evaluate the role of several risk factors, particularly infectious factors, in ectopic pregnancy. A total of 624 cases and 1,247 controls were compared for sociodemographic characteristics, cigarette smoking, sexual reproductive and surgical histories, and condition of conception. Different risk factors were found to be associated with an increased risk of ectopic pregnancy: pelvic inflammatory disease confirmed by celioscopy (OR = 3.8, 95%, CI = 2.1-6.9), Chlamydia trachomatis seropositivity (OR = 4.6, 95%, CI = 3.4-6.3), cigarette smoking at the time of conception with a dose-related effect (OR = 1.6 to 2.6), prior tubal surgery (OR = 1.8, 95%, CI = 1.0-3.1), prior uterus, surgery (OR = 3.2, 95%, CI = 1.4-7.1), prior ectopic pregnancy (OR = 6.4, 95%, CI = 3.6-11.3), induced conception cycle by clomiphene citrate (OR = 4.5, 95%, CI = 1.7-12.0), endometriosis (OR = 6.7, 95%, CI = 2.6-17.4) and maternal age, with a strong relation after the age of 35. These findings confirm the major role of pelvic inflammatory disease which could explain fifty percent of the cases and the one of cigarette smoking at the time of conception which could explain twenty percent of the cases.

Adolescent↗
PubMed1992

[Epidemiology of cleft palate and cleft lip inthe Rhône-Alpes/Auvergne/Jura region. Apropos of 903 cases registered 1978-1987].

Data from the Rhône-Alpes/Auvergne birth defects registry have been used to realise an epidemiological analysis of facial clefts (cleft palate and total cleft lip). Between 1978 and 1987, 903 cases have been ascertained giving an incidence of 0.67 per 1,000 for cleft lips with/without cleft palate (CLP) and 0.44 per 1,000 for cleft palates (CP). Several epidemiological characteristics have been studied: CLP are more frequent in males, and CP are more frequent in females. There is no detectable time trend, and birthweights are significantly lower in affected children than in the general population. There are more twins, more maternal epilepsy and more stimulations of ovulation in the studied sample than in the general population. The ranks of birth are higher in CP and CLP than in general population. The incidence of facial clefts in first degree relatives is 50 to 60 times the one in the general population, which is comparable to the literature findings.

Cleft Lip↗
PubMed1989

[Facial expression of the vertical dimension before and after orthognathic surgery].

The dynamic analysis of faces of the patients asking for a restoration for an aesthetic injury with a combined orthodontical-surgical treatment requires, besides a static morphological study: with photographs an cephalometric tracings; the study of their facial expression. In order to find out a method of classification of the units of expressive facial behavior, the mobility of the face is studied through the coding of the facial activity by P. EKMAN and W. FRIESEN i.e. the F.A.C.S.: Facial Action Coding System: From the video-recordings of faces and their photographic versions obtained after a pause on the video recorder, these authors have improvised a technic based on the visual observation of the anatomical basis of the movement in connection with facial expression and their description through minimal anatomical action units or A.U. These minimal units of behaviour combine to form mimics. Thanks to the F.A.C.S., the facial mimic of 18 patients before and after orthognatic surgery, and of six samples without dentofacial deformations has been studied. 18,844 AU have been observed, among 6,278 mimics made all together, with 604 different types. A classification of the mimics made by everyone and repeated in time has enabled us to establish a king of "norm" related to expression, allowing us some comparisons with expression of deformed patients. On one hand, for all of the patients examined, we have observed the mimics of the patients after surgery were more identical to the mimics of the samples. On the other hand, some differences have been distinguished concerning the changes of expressivity after surgery depending on the type of morphology before surgery: thus, rather a normal activity of the shrinking of the orbicularis oris has been observed, as well as the buccinator, among the open bites that had been operated on; and the activity of the uppe lip deriving from the "levator Labu Superious Caput infra orbitalis" has become more normal, and rather a normal activity of the lower lip deriving from mentalis, among the operated deep-bites. These results are akin to the clinical observations and suggest that the F.A.C.S. will be able to provide a coding for the study of facial expression.

Emotions↗
PubMed1989

[Risk factors for condylomata. A case control study].

The present study involves 214 patients whose cervical smear showed signs of human papilloma virus infection (HPV), matched with 1042 controls. We demonstrate increasing odds ratio with the total number of sexual partners since first sexual intercourse (p less than 0.0001). Moreover the cases have more often changed partners in the year preceding the diagnosis (odds ratio 2.6 p less than 0.0001). Their male partners more often have occupations that expose them to "extra-conjugal adventures" (p = 0.0005). Using a logistic regression analysis we demonstrate the independence of the masculine and feminine risk factors. After adjustment for age, reason for consulting and marital status the following factors are related to HPV infection: new partner, total number of sexual partners since first sexual intercourse and partner's occupation.

Adult↗
PubMed1988

[Detection of flat condylomata of the cervix uteri in the Department of Rhône].

In France's Rhône Department, the prevalence of cervical condylomas detected through cervical smears was measured in a systematic study. The rate determined was 1.67% of the women examined. This rate declines slightly with age among women up to 50 years of age, and declines more among those over 50. The study shows a higher frequency of cases in spring (May and June) and in autumn (September and October). We found important geographical variations, with overall higher rates in urban zones. However, there were certain notable exceptions (high rates in some rural areas and low rates in some urban zones). This survey will be followed up to examine the variation of this rate in time. The study has formed the basis of new hypotheses which must be verified by subsequent surveys.

Adolescent↗