Institut de veille sanitaire

About: Institut de veille sanitaire is a healthcare organization based out in Saint-Maurice, France. It is known for research contribution in the topics: Population & Public health. The organization has 1055 authors who have published 1547 publications receiving 56945 citations. The organization is also known as: INVS & InVS.

Epidemiology of viral encephalitis in 2011

Abstract: Encephalitis is an inflammation of the brain structures: neurons, vessels or glial cells. However, a consensual definition of the syndrome is difficult to obtain, and it is even more difficult to define encephalitis due a specific agent. Most viruses can be responsible for infectious encephalitis, but the number of encephalitis cases is very limited with regards of the incidence of benign infections from these pathogens. Viruses responsible for encephalitis can be animal-borne, vector-borne or human-to-human transmitted, they can infect preferentially immunocompetent or immunosuppressed patients, and some of them have demonstrated their epidemic potential. Herpes simplex encephalitis is recognized worldwide as the most frequent infectious encephalitis, and the only one with a validated specific treatment. Encephalitis following some viral infections such as measles or rabies can be prevented by vaccination. Unfortunately, effective treatment currently lacks for most encephalitic viral agents identified so far.

Definition of temperature thresholds: the example of the French heat wave warning system

Abstract: Heat-related deaths should be somewhat preventable. In France, some prevention measures are activated when minimum and maximum temperatures averaged over three days reach city-specific thresholds. The current thresholds were computed based on a descriptive analysis of past heat waves and on local expert judgement. We tested whether a different method would confirm these thresholds. The study was set in the six cities of Paris, Lyon, Marseille, Nantes, Strasbourg and Limoges between 1973 and 2003. For each city, we estimated the excess in mortality associated with different temperature thresholds, using a generalised additive model, controlling for long-time trends, seasons and days of the week. These models were used to compute the mortality predicted by different percentiles of temperatures. The thresholds were chosen as the percentiles associated with a significant excess mortality. In all cities, there was a good correlation between current thresholds and the thresholds derived from the models, with 0°C to 3°C differences for averaged maximum temperatures. Both set of thresholds were able to anticipate the main periods of excess mortality during the summers of 1973 to 2003. A simple method relying on descriptive analysis and expert judgement is sufficient to define protective temperature thresholds and to prevent heat wave mortality. As temperatures are increasing along with the climate change and adaptation is ongoing, more research is required to understand if and when thresholds should be modified.

Practical considerations for sensitivity analysis after multiple imputation applied to epidemiological studies with incomplete data

Abstract: Multiple Imputation as usually implemented assumes that data are Missing At Random (MAR), meaning that the underlying missing data mechanism, given the observed data, is independent of the unobserved data. To explore the sensitivity of the inferences to departures from the MAR assumption, we applied the method proposed by Carpenter et al. (2007). This approach aims to approximate inferences under a Missing Not At random (MNAR) mechanism by reweighting estimates obtained after multiple imputation where the weights depend on the assumed degree of departure from the MAR assumption. The method is illustrated with epidemiological data from a surveillance system of hepatitis C virus (HCV) infection in France during the 2001–2007 period. The subpopulation studied included 4343 HCV infected patients who reported drug use. Risk factors for severe liver disease were assessed. After performing complete-case and multiple imputation analyses, we applied the sensitivity analysis to 3 risk factors of severe liver disease: past excessive alcohol consumption, HIV co-infection and infection with HCV genotype 3. In these data, the association between severe liver disease and HIV was underestimated, if given the observed data the chance of observing HIV status is high when this is positive. Inference for two other risk factors were robust to plausible local departures from the MAR assumption. We have demonstrated the practical utility of, and advocate, a pragmatic widely applicable approach to exploring plausible departures from the MAR assumption post multiple imputation. We have developed guidelines for applying this approach to epidemiological studies.

A multicentre analysis of catheter-related infection based on a hierarchical model.

Abstract: To decrease intensive care unit (ICU)-acquired catheter-related infections (CRI), it is essential that healthcare workers receive training and that quality improvement programmes are in place. The aim of our study was to evaluate risk factors for catheter colonisation and infection, focussing specifically on local care bundles. Data were collected prospectively in 51 ICUs [7,188 patients, 8,626 central venous catheters (CVCs)] during two 6-month periods in 2007 and 2008, using a standardized questionnaire on catheter insertion, care and removal. Colonisation and CRI incidence were 6.1 and 2.2/1,000 CVC-days, respectively. A hierarchical mixed logistic model was used to identify risk factors for CRI and colonisation. Written CVC protocols were available in 46 (90 %) ICUs and were strictly followed in 38 ICUs. Factors significantly associated with CRI fell into three overall categories: (1) patient-related factors—immunosuppression [odds ratio (OR) 1.42, p = 0.02], medical diagnosis at admission (OR 1.64, p = 0.03) and trauma patient (OR 2.54, p < 0.001); (2) catheter-related factors—catheter rank (OR 1.7, p < 0.0001, non-subclavian catheter (OR 2.1, p < 0.001) and longer time with the catheter (p < 10−4); (3) centre-related factors—quantitative tip culture method (OR 2.55, p = 0.005) and alcohol-based povidone-iodine [OR 0.68, 95 % confidence interval (CI) 0.49–0.96] or alcohol-based chlorhexidine preparations (OR 0.69, 95 % CI 0.34–1.39) as compared to an aqueous povidone-iodine preparation (p < 0.001). We identified several risk factors for CRI that are amenable to improvement (preference for the subclavian route and use of an antiseptic solution containing alcohol). However, several patient-related factors were also found, and the use of quantitative catheter culture methods increased culture sensitivity, thereby increasing the CRI rate. Case-mix issues and the culture method should be taken into account when assessing the risk of CRI across centres.