Cost-effectiveness of bovine spongiform encephalopathy screening.
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Animals↗
Biomedical subjects
A J Valleron
Publications and source records attributed to A J Valleron.
Modeling the hepatitis C virus epidemic in France.
A backcalculation approach allows a reconstruction of the history of hepatitis C virus (HCV) infection in France and predictions of mortality from hepatocellular carcinoma (HCC) related to the virus. The model uses information from the literature about the natural history of the disease, epidemiological data about infected subjects in three French cohorts, and mortality data from national statistics. It seeks to determine the annual transition probabilities from chronic hepatitis to cirrhosis and the HCV incidence per year in the past. These unknowns are found by fitting the observed deaths from HCC that are attributable to HCV. Optimal values for these unknowns then allow to project the number of HCC deaths attributable to HCV for each year through 2025 (for patients infected before 1996). The model traces the HCV epidemic in France back to around the 1940s. It predicts that HCC mortality related to HCV will continue to increase through 2020 in the absence of treatment, with a 150% increase in the yearly incidence among men and 200% among women. The model also confirms that progression to cirrhosis depends strongly on sex and age. At any age, the annual probability of progression is 10 times greater for men than for women. Moreover, for men aged between 61 and 70 years, this probability is 300 times greater than that for men aged between 21 and 40 years.
Adult↗
Risk of hepatitis C virus transmission to surgeons and nurses from infected patients: model-based estimates in France.
BACKGROUND/AIM: The aim of this study was to estimate the annual number of cases of hepatitis C virus transmission from infected patients to uninfected surgeons or nurses due to percutaneous injury during invasive procedures. METHODS: The risk of transmission was estimated using a model involving three probabilities: A, that a health care worker sustains at least one percutaneous injury during a procedure; B, that 1 to 10% of patients are seropositive for hepatitis C virus; and C, that infection by this virus is transmitted to the Health Care Worker after such exposure. Probability A was estimated from the results of 2 French multicentric prospective trials. Probability C was estimated from the results of 9 international prospective studies. A ten-fold decreased risk was assumed for surgeons who wear gloves and use solid-bore suture needles. RESULTS: During a single procedure, the estimated probability of hepatitis C virus transmission from an infected patient to an uninfected surgeon ranged from 4.2x10(-5)% to 4.2x10(-4)%, and from 2.98x10(-6)% to 2.98x10(-5)% to an uninfected nurse. For surgeons, the estimated annual cumulative risk of occupational infection ranged from 0.01% to 0.1% (1 in 10000 to 1 in 1000), and for nurses from 0.0054% to 0.054% (1 in 18700 to 1 in 1900). CONCLUSIONS: Between 2 and 21 surgeons out of a total 20000 are estimated to acquire occupationally-related hepatitis C virus infection, and between 16 and 167 nurses out of a total 300000. These estimates strongly justify introducing preventive measures to protect health care workers from bloodborne infection.
France↗
Correlation between hepatitis C virus prevalence and hepatocellular carcinoma mortality in Europe.
In Europe, as worldwide, hepatocellular carcinoma (HCC) death rates are highly variable. Recent studies have reported that hepatitis C virus (HCV) infection may be responsible for the increased mortality from HCC in the UK and in France. We investigate here the potential relationship between HCC mortality and HCV prevalence in Europe. Population and mortality data of HCC were obtained for 22 European countries from the World Health Organization (WHO) databank. Age-standardized death rates were computed. The HCV prevalence among blood donors and the WHO estimate of HCV prevalence were used as two indicators of prevalence in the general population, when data were available. Spearman rank analysis was conducted between HCC mortality and HCV prevalence. For men, age-standardized death rates per 100 000 varied from 0.61 (Greece) to 12.19 (Hungary). HCC mortality among men was positively correlated with HCV prevalence among blood donors and with the WHO estimate: rank correlation coefficients were, respectively, 0.76 (P = 0.02) and 0.72 (P = 0.03). This study showed that the reported differences of HCC mortality in Europe correlate with HCV prevalence.
Carcinoma, Hepatocellular↗
Evaluation of clinical case definitions of influenza: detailed investigation of patients during the 1995-1996 epidemic in France.
Using clinical predictors, we evaluated clinical case definitions of influenza during the 1995-1996 outbreak in France. Thirty-five general practitioners collected virological specimens and clinical data. Predictors of influenza virus infection were selected with logistic regression models. The results varied with the influenza virus subtype: temperature of >38.2 degrees C, stiffness or myalgia, rhinorrhea, and cough were predictive of influenza A/H3N2, whereas fatigue, lacrimation or conjunctival injection, and the absence of stiffness or myalgia were predictive of influenza A/H1N1. On the basis of this analysis and data from the literature, 12 clinical case definitions were evaluated for their abilities to diagnose influenza virus infection. They were associated with positive predictive values of 27% to 40% and negative predictive values of 80% to 91%. We conclude that focused studies evaluating clinical case definitions of influenza with use of subsets of patients should accompany population-based disease surveillance for optimal estimates of the disease burden associated with influenza epidemics.
Disease Outbreaks↗
When did bovine spongiform encephalopathy (BSE) start? Implications on the prediction of a new variant of Creutzfeldt-Jakob disease (nvCJD) epidemic.
BACKGROUND: Knowing the starting date of the BSE epidemic and its size at the very beginning is crucial to interpret the timing of the nvCJD cases and to forecast the nvCJD epidemic. The first cases occurred in 1985. The models devised by Anderson (back-calculation) and Dealler (age-period-cohort) led to an estimate of less than 50 cases in 1983, and none earlier. Here, we applied age-cohort models to the BSE data in order to estimate the earliest possible date of the first unrecognized BSE cases. METHODS: The numbers of confirmed BSE cases in the UK, by age group and by calendar year from 1988 to 1996, were analysed by Poisson regression. The cases' age distribution was considered as constant between the different birth cohorts. The herd's age structure was taken into account. RESULTS: According to the models, BSE cases may have occurred as early as 1980. The expected number of cases before 1990 is almost twice the number of confirmed cases and exceeds by more than 20% the expected value of Anderson's model. The scenario of first human exposure in 1980 leads to fewer future nvCJD cases than predicted by Cousens with exposure patterns starting in 1983 or 1985. CONCLUSION: The first birth cohort available, consisting of two cases older than 10 in 1988, does not allow any projections before 1980. Moreover, confidence intervals are wide and the power of the study is limited by the great dispersion of the data; the precision of the estimations would be improved by considering geographical incidence. Nevertheless, our projections are consistent with Wilesmith's survey of rendering plants relating the emergence of BSE to the dramatic fall in the proportion of meat and bone meal following solvent extraction, initiated in the late 1970s (65% in 1977 to 10% in 1983).
Animals↗
Persistence of susceptibility to measles in France despite routine immunization: a cohort analysis.
OBJECTIVES: This study examined the impact of French routine programs urging the combined measles-mumps-rubella immunization of 15-month-old children. METHODS: We applied a cohort analysis to surveillance data collected by general practitioners to estimate the cumulative incidence rate per 1000 unvaccinated children and the proportion of susceptible children, by age and for each birth cohort between 1985 and 1995. RESULTS: More than 70% of unvaccinated children born in 1985 and 1986 had measles by the age of 10. This incidence rate dramatically decreased after implementation of the routine measles-mumps-rubella immunization program in 1989, but the proportion of 5-year-olds susceptible to measles has not decreased appreciably. In 1996, more than 15% of the children born between 1990 and 1995 were susceptible. CONCLUSIONS: The measles vaccine coverage achieved by the French routine immunization program remains insufficient as regards reducing the number of susceptible children.
Age Distribution↗
FluNet as a tool for global monitoring of influenza on the Web.
In collaboration with the Institut National de la Santé et de la Recherche Médicale, the World Health Organization (WHO) has developed an Internet application linking the global WHO network of influenza centers (FluNet; http://oms.b3e.jussieu.fr/flunet/). During 1997, 22 pilot centers entered data on influenza activity and viral laboratory results directly into FluNet via secured access. In addition, 54 centers sent data to WHO for entry. Four countries (the Russian Federation, Romania, Sweden, and the United Kingdom) reported widespread outbreaks of at least 4 weeks' duration. The FluNet server ran 24 hours a day without interruption. To improve management and enhance standardization of reporting, this early-alert system for the global monitoring of influenza provides international and national authorities, the public, and the media with full access to real-time epidemiological and virological information.
Disease Outbreaks↗
[Transmission modes of hepatitis C virus].
SITUATION IN FRANCE: The prevalence of hepatitis C virus (HCV) infection in the French population is estimated at 1%, a level similar to that in other western countries. USUAL CONTAMINATION ROUTES: Epidemiological studies, together with gene typing, have made it possible to distinguish transmission modes. A history of intravenous drug abuse or transfusion is found in 60 to 80% of all subjects infected by the HCV. Other documented modes of contamination include hemodialysis, organ transplantation, accidental occupational-related puncture and mother-infant transmission. OTHER ROUTES: Sexual or intra-familial nonsexual transmission is uncommon and related to the length of exposure and the stage of HCV infection in the "source" subjects. Cases of HCV transmission have been reported during medical procedures. Currently the mode of of transmission is unknown in 20 to 40% of the cases.
Blood Transfusion↗
SHARE: a tool to analyze and assess strategies in health care organization management.
In health care organizations, management of both human and material resources implies decision making. When seemingly equivalent strategies are possible, simulation can help to make a decision on better grounds. The SHARE workframe was designed to address the specificities of health care and to provide a comprehensive environment for modelling and simulating health care processes. The typology of objects is defined as Actors, subdivided in Clients and Resources and Elementary Operations. Graphical tools allow us to build processes from these objects and to create their relationships. Various strategies based on either clinical or managerial changes may be investigated. After a simulation, graphical tools allow us to display summary information on the utilization of all actors, waiting times, and goodness of execution. The use of SHARE is exemplified with the analysis and simulation of changes in the Pulmonary Function Testing Laboratory of the Saint-Antoine Hospital, Paris.
Computer Simulation↗
Estimation of the past and future burden of mortality from mesothelioma in France.
OBJECTIVES: Firstly to evaluate future mortality from mesothelioma in France with an age-period-cohort approach and evaluate different hypotheses on risk of mesothelioma for the most recent birth cohort. Secondly to compare the results with a British and an American study. Thirdly to study if any trends were detectable on data for women which would be consistent with the consequences of increasing environmental exposure to asbestos. METHODS: Estimates of mortality from mesothelioma among men and women in France from 1950 to 1995 were based on the analysis of the pleural cancer mortality data coded 163 in the ninth revision of the international classification of diseases (ICD-9). Correction factors were used to derive the mortality from mesothelioma from these data, based on two regional registries. The analysis of the past mortality data has been performed by an age-cohort model (with a maximum likelihood technique). Predictions of deaths from mesothelioma over the next 50 years were based on four different assumptions on the risk of death from mesothelioma in future birth cohorts. RESULTS: The predicted lifetime probability of dying from mesothelioma increases until the last birth cohort 1964-8 among men whereas it decreases strongly from the 1954-8 birth cohort among women. The projected numbers of deaths from mesothelioma in France until 2020 are similar, whichever hypothesis is considered: around 20,000 deaths from mesothelioma might occur among men and 2900 among women from 1996 to 2020. CONCLUSIONS: French data show an increasing lifetime probability of death from mesothelioma in the more recent male cohorts. Although the mortality burden can be predicted until 2020, and is intermediate between the United Kingdom and United States estimates, there is still high uncertainty on the figures after 2020. No increase is found in women, and this does not support the hypothesis that current environmental exposure to asbestos could be associated with a detectable risk of death. Specific surveillance should be set up to monitor future trends or their absence.
Adult↗
Modelling health care processes with SHARE.
This paper describes the "SHARE" workframe, designed to provide a comprehensive environment for modeling and simulating health care processes. The objects defined within SHARE are Actors, subdivided in Clients and Resources, and Elementary Operations. Graphical tools allow to build processes from these objects, and to specify their relationships. Various strategies based on either clinical or managerial changes may be investigated. Summary information on the utilization of all actors, on waiting times and goodness of execution may be displayed after a simulation. Better description of processes, and their study a priori will improve reliability, quality of care and satisfaction of patients.
Appointments and Schedules↗
Participation of French general practitioners in public health surveillance: a multidisciplinary approach.
STUDY OBJECTIVES: To evaluate the feasibility of a novel approach to measure compliance of sentinel general practitioners (SGPs) in sentinel public health surveillance and to determine the characteristics in the SGP's profile that can be objectively associated with their perseverance in public health surveillance. DESIGN: Prospective study of the compliance of the SGPs (compliance being defined as the length of time during which an SGP complies with a given theoretical surveillance protocol) and qualitative study of the determinants of their initial motivations (using group and face to face interviews). SETTING: The 1970 SGPs who have participated in the Sentinel system since 1984. PARTICIPANTS: Among them, the 502 SGPs recruited since 1 July 1992 have been questioned by mailed questionnaire and 20 SGPs have been questioned during face to face semistructured interviews. MAIN RESULTS: According to the maximum number of silences allowed by the given theoretical protocol, median compliances varied between 1.9 months (95% CI = (1.8, 2.0)) and 14.3 months (95% CI = (13.8, 15.2)). In multivariate analysis, long compliances for SGPs with a < or = 5 or > or = 20 years seniority was seen and an interest in using multimedia home servers. On the other hand, interest in local epidemiological surveys and previous experience with other surveillance networks or clinical trials were associated with short compliances. No statistical association was found between compliance and computing experience, having a medical secretary, a particular feeling of being a "public health actor", or the desire to belong to a GPs' network. A thematic analysis of interview records showed that the main motivation of the SGPs was their need to share their experiences and to self evaluate by comparison with colleagues by the means of a surveillance system that would be used as a health information system. CONCLUSIONS: The longitudinal method used in this study was shown to be an efficient tool to monitor non-compliant SGPs with respect to given surveillance protocols. Furthermore, this approach allows the selection out of the SGPs' profile the characteristics that are associated with a longer compliance. The additional variables to be taken into account in this profile could be identified among the topics, attitudes, and experiences collected during the semistructured interviews. This work considers the question of understanding what determines the motivation of GPs to participate in public health surveillance and what are their expectations of feed back. This question is essential if information systems in general practice are to be implemented.
Cooperative Behavior↗
Surveillance of influenza-like illness in France. The example of the 1995/1996 epidemic.
STUDY OBJECTIVES: To discover if continuous computerised collection of morbidity data through a medical practice based sentinel network can be used to monitor influenza-like illness (ILI) epidemics. To obtain rough estimates of influenza vaccine effectiveness. DESIGN: Continuous passive surveillance of ILI through a computerised network of voluntary sentinel general practitioners (SGPs) in France (Sentinelle system). SETTING: Five hundred SGPs practices. PARTICIPANTS: Since 1984, SGPs updated a database with information on eight communicable diseases including ILI, via videotext terminals. Each ILI case is defined by the association of a sudden fever of 39 degrees C or above, respiratory symptoms, and myalgias. An ILI epidemic is detected when the national weekly incidence rate exceeds a seasonal threshold for two successive weeks. MAIN RESULTS: An ILI epidemic was reported from November 1995 to January 1996. In total, 13,951 individual cases were reported by SGPs during the epidemic period. The size of the epidemic (number of patients consulting a GP) was estimated to be 2,370,000 subjects. Maps of the epidemic showed that all regions have reported a high level ILI activity. The attack rate was the highest in school age children (13.5/100) and decreased as the age rose. Nearly 6% of the reported ILI cases among adults and elderly were vaccinated. The flu vaccine effectiveness against ILI was estimated to be 66% (95% CI 73%, 92%), ranging between 83% (95% CI 73%, 92%) among the subjects aged 15 to 24 years old to 16% (95% CI -12%, 44%) among the subjects aged 75 years or older. CONCLUSIONS: The Sentinelle system demonstrated adequate sensitivity and timeliness regarding ILI epidemic. Moreover, results of the monitoring were made available on the internet to increase the dissemination of information. Also, estimates of influenza vaccine effectiveness have been easily obtained. Altogether, they represent key points for the control of crisis situation such as ILI epidemics or pandemics.
Adolescent↗
[Access to social coverage of uninsured patients attending a hospital clinic: a historical cohort study at the Baudelaire outpatient clinic in Paris].
BACKGROUND: In France health insurance coverage is universal (see note at the end of the text), nevertheless some people remain uninsured. In this high-risk population, the lack of insurance coverage contributes to the aggravation of health, by reducing access to medical care. In 1992, the Baudelaire consultation was incorporated into the outpatient clinic of Saint-Antoine hospital (Paris, France), to provide the uninsured with the same access as any other patient--but free of charge--to medical care. Social care was also provided in particular by assisting the uninsured in applying for insurance coverage. Our objectives were to quantify the delay in obtaining insurance coverage and to study whether the sociodemographic characteristics of these patients were associated with inequalities in terms of delays. METHODS: All patients attending the consultation for the first time in 1994 were included (n = 623). Because of differences linked to the French social security system, analysis was performed into two groups according to the existence of a prior insurance coverage. Delay in obtaining or recovering insurance coverage was considered as the key variable. The socio-demographic factors linked to the rates of access to insurance coverage were determined using Cox proportional hazards regression models. We also examined the factors linked with the existence of a prior insurance coverage by logistic regression modeling. RESULTS: Within one year 96% of the patients who had had insurance coverage in the past, and 63% of the patients who had not, were insured. No factor, whether nationality, educational level, socio-professional category, family situation, type of housing, made of income was found to be linked with obtaining or recovering insurance coverage. However, nearly all these factors were related with the existence of prior insurance coverage. CONCLUSIONS: Our approach of systematically providing social care allows 70% of uninsured patients to obtain insurance coverage within one year. This approach probably contributes to an improvement by facilitating access to mainstream health care. Moreover, no difference in delay in obtaining insurance coverage was found associated with sociodemographic characteristics.
Adult↗
Sentiweb remains efficient tool for nationwide surveillance of disease.
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Communicable Diseases↗
A computer simulation model for the spread of nosocomial infections caused by multidrug-resistant pathogens.
A Monte Carlo simulation model was developed for the spread of antibiotic-resistant bacteria in hospital units. The model allows for the representation of every patient and staff member. Staff-patient interactions, staff handwashing compliance, admission of colonized patients, and antibiotic use are included in the model. The simulation model provides colonization curves for patients and staff and offers the possibility of simulating different kinds of hospital units. Simulation of the spread of an antibiotic-resistant pathogen in an intensive care unit was performed. We studied the impact of handwashing compliance on colonization. The importance of handwashing in preventing colonization and the influence of admission of colonized patients in perpetuating an epidemic were confirmed by the model. The model offers a new approach to modeling the spread of nosocomial pathogens in hospital units. It allows one to study the impact of infection control measures and represents a valuable educational tool for staff.
Algorithms↗