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In October 2006 the Dutch Ministry of Health, Welfare and Sport announced that the use of pre-randomisation in study designs is admissible and not in conflict with the Dutch Medical Research in Human Subjects Act. With pre-randomisation, the conventional sequence of obtaining informed consent followed by randomisation is reversed. According to the original pre-randomisation design (Zelen design), participants are randomised before they are asked to consent; after randomisation, only participants in the experimental group are asked to consent to treatment and effect measurement. In the past, pre-randomisation has seldom been used, and when it was, it was often under the wrong circumstances. Awareness regarding the ethical, legal and methodological objections to pre-randomisation is increasing. About a decade ago, we illustrated the applicability and acceptability of pre-randomisation by means of a fictitious heroin provision trial. In general, pre-randomisation is justified if valid evaluation of the effects of an intervention is impossible using a conventional randomised design, e.g., if knowledge of the intervention may lead to non-compliance or drop-out in the control group, or when the intervention is an educational programme. Other requirements for pre-randomisation include the following: the study has a clinically relevant objective, it is likely that the study will lead to important new insights, the informed consent procedure bears no potential harm to participants, at least standard care is offered to participants in the control group, and the approval of an independent research ethics committee is obtained.

Objective: To elucidate the cause of an epidemic of gastroenteritis amongst the guests and waiting staff of two weddings celebrated on the same day in the same restaurant., Design: Retrospective and descriptive., Method: Following an outbreak of gastroenteritis amongst 215 wedding guests and restaurant staff in 1999, the Public Health Institute Midden-Limburg, the Netherlands, inventoried the demographic and clinical variables and consumed foods by means of a structured written interview. Faecal samples and remaining food products were bacteriologically examined, and later on faeces were virologically examined for the presence of the Norwalk-like virus (NLV). The attack rates and the incidence rates of NLV-positive faecal specimens amongst consumers and non-consumers of specific food products were calculated, as well as the corresponding relative risks with 95% confidence intervals., Results: The overall attack rate was 66%. An NLV with the same genotype was found statistically significantly more frequently in faecal specimens of ill persons compared with non-ill individuals. Of the 61 different dishes served, two showed a statistically significant relation with being ill. These food products were eaten by 26% of the ill persons. No statistically significant association was found between NLV-positive faeces and consumption of a specific dish. The index case began having symptoms of gastroenteritis at the morning of the wedding party, before food was served. The guests of the two wedding parties used the same entrance and toilets., Conclusion: The epidemic was caused by a single NLV strain. No association could be found between the consumption of certain food products and being ill. The NLV epidemic was probably caused through direct or indirect contact between wedding guests and restaurant personnel. In the case of such reports of gastroenteritis epidemics, it is strongly recommended to test faecal, food product and environment samples for both bacteria and viruses, with an emphasis on NLV, to ensure early diagnosis.

Since World War II, all sorts of protective measures have been taken for people who receive medical care or who are involved in scientific research. More and more, informed consent has become the standard. In the field of experimental therapeutical research, informed consent is still a controversial subject; the individual person's interests versus general interests. But informed consent appears to have become such an absolute prerequisite for all types of observational research that the future of epidemiological research based on existing data is threatened. According to both the Declaration of Helsinki and the Dutch Law for Protection of Persons, it is possible to omit asking individual informed consent under certain circumstances. Permission for research could then be given by a supervisory board or a medical-ethical commission. After all, informed consent was never meant to be a goal of its own, but a means for self-protection and securing the right to autonomy. In situations where this right is curbed for other reasons, it appears that insisting on informed consent misses its target completely.

Objective: To discover the cause of an outbreak of gastroenteritis after a family party., Design: Retrospective cohort study., Methods: All 109 party-goers were asked to complete a written questionnaire about consumed food products and demographic and clinical variables and to hand in a faeces sample. The data were collected at the Public Health Institute Midden-Limburg, the Netherlands. Faeces and the remaining food products were examined microbiologically. The attack rates and the incidence rates of positive faeces culture among consumers and non-consumers of specific food products were calculated as well as the corresponding relative risks (RR) with 95% confidence intervals (95% CI)., Results: The overall attack rate was 35%. Salmonella typhimurium phage type 20 was found in 'Coburger ham' and statistically significantly more frequently in faeces of ill compared with non-ill party-goers (RR: 6.4; 95% CI: 2.5-16.1). Twenty-eight different food products were served. Consumption of 'Coburger ham' only, was statistically significantly related to a positive faeces culture (RR: 4.1; 95% CI: 2.0-8.5). Only consumption of 'Coburger ham' and of 'bone ham' was statistically significantly related to being ill (RR: 2.4; 95% CI: 1.5-4.0 and RR: 1.4; 95% CI: 1.1-1.9, respectively). 'Coburger ham' and 'bone ham' originated from the same batch of raw meat and were prepared in the same manner in the same salt bath. The shorter duration of salting and drying of 'Coburger ham' compared with 'bone ham' corresponded with a higher relative risk of becoming ill., Conclusion: Consumption of 'bone ham' and 'Coburger ham' infected with S. typhimurium phage type 20 caused the outbreak. Traditional salting, drying and smoking of raw pork meat was not antimicrobiologically effective against S. typhimurium. Investigation of the antimicrobiological effect of the traditional preparation of meat and the importance of Good Manufacturing Practices and quality control in all stages of production of pork meat, according to the principles of Hazard Analysis and Critical Control Points, is advised.

In this article the sex- and age-specific trends and geographical distribution of asbestos related pleural mesothelioma mortality in the Netherlands between 1970 and 1987 are investigated. For men total mortality increased from 10.8 per million during 1970-1978 to 20.9 per million during 1979-1987. The highest mortality occurred with 147.7 per million in 1987 in the age group between 65 and 74 years. Mortality rates for the age group between 55 and 64 years amounted to 96.5 per million in 1987. The geographical distribution over the country showed a strong concentration of male mesothelioma cases in the regions with many harbours, shipyards and heavy industries round Amsterdam, IJmuiden, Rotterdam, Dordrecht and Walcheren. Using linear regression techniques, it was calculated that several thousands new mesothelioma cases will occur in the Netherlands during the next two decades. A significant decrease in mesothelioma mortality can not be expected before 2010.