Measuring human-error probabilities in drug preparation: a pilot simulation study

Objectives: Designing a safe medication process requires the ability to model its reliability using methods such as probabilistic risk assessment (PRA). However, lack of data, especially on human-error probabilities (HEPs), limits its use. To assess whether small-scale simulations could help generate HEP data, a pilot study was conducted among nurses and anaesthetists. It focused on two core activities, namely, the manual preparation of medications and the arithmetic necessary to prepare drugs. Its specific objectives were to evaluate whether HEPs could be high enough to be measurable and to determine whether these HEPs could be sensitive to individuals and task details. These would give some insight into the level of detail required by PRA analysis. Methods: Thirty nurse and 28 anaesthetist volunteers were involved in the experiment. Nurses and anaesthetists had to prepare medications for 20 patients and 22 syringes of various drugs, respectively. Both groups had to perform 22 calculations relating to the preparation of drugs. HEPs, distribution of HEPs and dependency of HEPs on individuals and task details were assessed. Results: In the preparation tasks, overall HEP was 3.0% for nurses and 6.5% for anaesthetists. In the arithmetic tasks, overall HEP was 23.8% for nurses and 8.9% for anaesthetists. A statistically significant difference was noted between the two groups. In both preparation and arithmetic tasks, HEPs were dependent on individual nurses but not on individual anaesthetists. In every instance, HEPs were dependent on task details. Conclusion: Our study illustrates that small-scale simulations represent an interesting way of generating HEPs. HEPs are, indeed, in the range of 10−2 and 10−1. But in most cases, HEPs depend heavily on operators and task details. This dependency means that the influence of these parameters must be determined before advanced PRA analysis. There is therefore an urgent need to develop experimental research into assessing this influence by means of randomised controlled trial

Online detection and quantification of epidemics

<p>Abstract</p> <p>Background</p> <p>Time series data are increasingly available in health care, especially for the purpose of disease surveillance. The analysis of such data has long used periodic regression models to detect outbreaks and estimate epidemic burdens. However, implementation of the method may be difficult due to lack of statistical expertise. No dedicated tool is available to perform and guide analyses.</p> <p>Results</p> <p>We developed an online computer application allowing analysis of epidemiologic time series. The system is available online at <url>http://www.u707.jussieu.fr/periodic_regression/</url>. The data is assumed to consist of a periodic baseline level and irregularly occurring epidemics. The program allows estimating the periodic baseline level and associated upper forecast limit. The latter defines a threshold for epidemic detection. The burden of an epidemic is defined as the cumulated signal in excess of the baseline estimate. The user is guided through the necessary choices for analysis. We illustrate the usage of the online epidemic analysis tool with two examples: the retrospective detection and quantification of excess pneumonia and influenza (P&I) mortality, and the prospective surveillance of gastrointestinal disease (diarrhoea).</p> <p>Conclusion</p> <p>The online application allows easy detection of special events in an epidemiologic time series and quantification of excess mortality/morbidity as a change from baseline. It should be a valuable tool for field and public health practitioners.</p

Planning for the next influenza H1N1 season: a modelling study

<p>Abstract</p> <p>Background</p> <p>The level of herd immunity before and after the first 2009 pandemic season is not precisely known, and predicting the shape of the next pandemic H1N1 season is a difficult challenge.</p> <p>Methods</p> <p>This was a modelling study based on data on medical visits for influenza-like illness collected by the French General Practitioner Sentinel network, as well as pandemic H1N1 vaccination coverage rates, and an individual-centred model devoted to influenza. We estimated infection attack rates during the first 2009 pandemic H1N1 season in France, and the rates of pre- and post-exposure immunity. We then simulated various scenarios in which a pandemic influenza H1N1 virus would be reintroduced into a population with varying levels of protective cross-immunity, and considered the impact of extending influenza vaccination.</p> <p>Results</p> <p>During the first pandemic season in France, the proportion of infected persons was 18.1% overall, 38.3% among children, 14.8% among younger adults and 1.6% among the elderly. The rates of pre-exposure immunity required to fit data collected during the first pandemic season were 36% in younger adults and 85% in the elderly. We estimated that the rate of post-exposure immunity was 57.3% (95% Confidence Interval (95%CI) 49.6%-65.0%) overall, 44.6% (95%CI 35.5%-53.6%) in children, 53.8% (95%CI 44.5%-63.1%) in younger adults, and 87.4% (95%CI 82.0%-92.8%) in the elderly.</p> <p>The shape of a second season would depend on the degree of persistent protective cross-immunity to descendants of the 2009 H1N1 viruses. A cross-protection rate of 70% would imply that only a small proportion of the population would be affected. With a cross-protection rate of 50%, the second season would have a disease burden similar to the first, while vaccination of 50% of the entire population, in addition to the population vaccinated during the first pandemic season, would halve this burden. With a cross-protection rate of 30%, the second season could be more substantial, and vaccination would not provide a significant benefit.</p> <p>Conclusions</p> <p>These model-based findings should help to prepare for a second pandemic season, and highlight the need for studies of the different components of immune protection.</p

Emergency vaccination of rabies under limited resources – combating or containing?

BACKGROUND: Rabies is the most important viral zoonosis from a global perspective. Worldwide efforts to combat the disease by oral vaccination of reservoirs have managed to eradicate wildlife rabies in large areas of central Europe and North-America. Thus, repeated vaccination has been discontinued recently on a geographical scale. However, as rabies has not yet been eradicated globally, a serious risk of re-introduction remains. What is the best spatial design for an emergency vaccination program – particularly if resources are limited? Either, we treat a circular area around the detected case and run the risk of infected hosts leaving the limited control area, because a sufficient immunisation level has not yet been built up. Or, initially concentrate the SAME resources in order to establish a protective ring which is more distant from the infected local area, and which then holds out against the challenge of the approaching epidemic. METHODS: We developed a simulation model to contrast the two strategies for emergency vaccination. The spatial-explicit model is based on fox group home-ranges, which facilitates the simulation of rabies spread to larger areas relevant to management. We used individual-based fox groups to follow up the effects of vaccination in a detailed manner. Thus, regionally – bait distribution orientates itself to standard schemes of oral immunisation programs and locally – baits are assigned to individual foxes. RESULTS: Surprisingly, putting the controlled area ring-like around the outbreak does not outperform the circular area of the same size centred on the outbreak. Only during the very first baitings, does the ring area result in fewer breakouts. But then as rabies is eliminated within the circle area, the respective ring area fails, due to the non-controlled inner part. We attempt to take advantage of the initially fewer breakouts beyond the ring when applying a mixed strategy. Therefore, after a certain number of baitings, the area under control was increased for both strategies towards the same larger circular area. The circle-circle strategy still outperforms the ring-circle strategy and analysis of the spatial-temporal disease spread reveals why: improving control efficacy by means of a mixed strategy is impossible in the field, due to the build-up time of population immunity. CONCLUSION: For practical emergency management of a new outbreak of rabies, the ring-like application of oral vaccination is not a favourable strategy at all. Even if initial resources are substantially low and there is a serious risk of rabies cases outside the limited control area, our results suggest circular application instead of ring vaccination

Association of influenza epidemics with global climate variability

The reasons for the seasonality and annual changes in the impact of influenza epidemics remain poorly understood. We investigated the covariations between a major component of climate, namely the El Niño Southern Oscillation (ENSO), and indicators of the impact of influenza, as measured by morbidity, excess mortality and viral subtypes collected in France during the period 1971–2002. We show that both the circulating subtype and the magnitude of ENSO are associated with the impact of influenza epidemics. Recognition of this association could lead to better understanding of the mechanisms of emergence of influenza epidemics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42662/1/10654_2004_Article_DO00002450.pd

SCHUBERT AUDIT : système expert pour l'aide à l'audit qualité des élevages de truites de consommation et de repeuplement. Première maquette opérationnelle

Pour compléter les dispositions prévues par la loi n° 84-512 relative à la gestion piscicole et à la pêche, et, en prévision des futures exigences européennes, il nous est apparu important de mettre à la disposition des responsables piscicoles un outil permettant d'évaluer l'aptitude des élevages à produire un poisson d'une qualité définie. Une maquette de cet outil a été réalisée grâce à l'adaptation d'une méthode ayant fait ses preuves en milieu industriel, l'audit qualité, au cas particulier des piscicultures et à son informatisation sous la forme d'un système expert, SCHUBERT AUDIT. Nous nous sommes intéressés plus précisément aux élevages produisant des truites. L'adaptation de l'audit qualité a débouché sur : — la définition précise des besoins des clients, soit la destination des truites, l'espèce, le stade de développement et le niveau d'assurance qualité requis pour fonder sa confiance. — l'examen des différents facteurs d'audit portant sur les "5M" de la qualité (Matériel, Matière, Main-d'oeuvre, Milieu, Méthode) et destiné à évaluer les qualités sanitaire, alimentaire, halieutique, écologique et génétique des truites. Cet examen conduit à la notation des facteurs d'audit et à leur pondération en fonction de leur importance respective dans l'obtention de la qualité et à la détermination d'une note globale de l'élevage représentant son aptitude à satisfaire les besoins des utilisateurs. Le système expert SCHUBERT AUDIT contient un dictionnaire de 341 termes et deux fichiers de règles de production totalisant ensemble 464 règles. Son moteur d'inférence utilise un algorithme de chaînage avant et un algorithme de chaînage arrière. Le chaînage avant fait appel au premier fichier de règles de production. Il permet de déterminer un référentiel matérialisant les besoins du client. Le chaînage arrière, associé au second fichier de règles, permet d'évaluer la situation réelle de l'élevage et de la comparer à ce référentiel. Quelques essais concluants ont été effectués à partir d'exemples connus de l'expert. Cependant, il reste à enrichir la base de connaissances du système expert, à améliorer son ergonomie et à en réaliser la validation complète

SCHUBERT AUDIT : système expert pour l'aide à l'audit qualité des élevages de truites de consommation et de repeuplement. Première maquette opérationnelle

Pour compléter les dispositions prévues par la loi n° 84-512 relative à la gestion piscicole et à la pêche, et, en prévision des futures exigences européennes, il nous est apparu important de mettre à la disposition des responsables piscicoles un outil permettant d'évaluer l'aptitude des élevages à produire un poisson d'une qualité définie. Une maquette de cet outil a été réalisée grâce à l'adaptation d'une méthode ayant fait ses preuves en milieu industriel, l'audit qualité, au cas particulier des piscicultures et à son informatisation sous la forme d'un système expert, SCHUBERT AUDIT. Nous nous sommes intéressés plus précisément aux élevages produisant des truites. L'adaptation de l'audit qualité a débouché sur : — la définition précise des besoins des clients, soit la destination des truites, l'espèce, le stade de développement et le niveau d'assurance qualité requis pour fonder sa confiance. — l'examen des différents facteurs d'audit portant sur les "5M" de la qualité (Matériel, Matière, Main-d'oeuvre, Milieu, Méthode) et destiné à évaluer les qualités sanitaire, alimentaire, halieutique, écologique et génétique des truites. Cet examen conduit à la notation des facteurs d'audit et à leur pondération en fonction de leur importance respective dans l'obtention de la qualité et à la détermination d'une note globale de l'élevage représentant son aptitude à satisfaire les besoins des utilisateurs. Le système expert SCHUBERT AUDIT contient un dictionnaire de 341 termes et deux fichiers de règles de production totalisant ensemble 464 règles. Son moteur d'inférence utilise un algorithme de chaînage avant et un algorithme de chaînage arrière. Le chaînage avant fait appel au premier fichier de règles de production. Il permet de déterminer un référentiel matérialisant les besoins du client. Le chaînage arrière, associé au second fichier de règles, permet d'évaluer la situation réelle de l'élevage et de la comparer à ce référentiel. Quelques essais concluants ont été effectués à partir d'exemples connus de l'expert. Cependant, il reste à enrichir la base de connaissances du système expert, à améliorer son ergonomie et à en réaliser la validation complète

Voluntary reporting system in anaesthesia: is there a link between undesirable and critical events?

P Garnerin, quality manager and F Clergue, department head and professor J-F Sicard, anaesthetist and F Bonnet, department head and professor Background—Reporting systems in anaesthesia have generally focused on critical events (including death) to trigger investigations of latent and active errors. The decrease in the rate of these critical events calls for a broader definition of significant anaesthetic events, such as hypotension and bradycardia, to monitor anaesthetic care. The association between merely undesirable events and critical events has not been established and needs to be investigated by voluntary reporting systems. Objectives—To establish whether undesirable anaesthetic events are correlated with critical events in anaesthetic voluntary reporting systems. Methods—As part of a quality improvement project, a systematic reporting system was implemented for monitoring 32 events during elective surgery in our hospital in 1996. The events were classified according to severity (critical/undesirable) and nature (process/outcome) and control charts and logistic regression were used to analyse the data. Results—During a period of 30 months 22% of the 6439 procedures were associated with anaesthetic events, 15% of which were critical and 31% process related. A strong association was found between critical outcome events and critical process events (OR 11.5 (95% confidence interval (CI) 4.4 to 27.8)), undesirable outcome events (OR 4.8 (95% CI 2.0 to 11.8)), and undesirable process events (OR 4.8 (95% CI 1.3 to 13.4)). For other classes of events, risk factors were related to the course of anaesthesia (duration, occurrence of other events) and included factors determined during the pre-anaesthetic visit (risk of haemorrhage, difficult intubation or allergic reaction). Conclusion—Undesirable events are associated with more severe events and with pre-anaesthetic risk factors. The way in which information on significant events can be used is discussed, including better use of preoperative information, reduction in the collection of redundant information, and more structured reporting. (Quality in Health Care 2000;9:203–209) Key Words: reporting system; correlation analysis; quality assessment; adverse events; anaesthesi