Generalisability of the results of the Dutch-Belgian randomised controlled lung cancer CT screening trial (NELSON): does self-selection play a role?

The degree of self-selection in the Dutch-Belgian randomised controlled lung cancer screening trial (NELSON) was determined to assess the generalisability of the study results. 335,441 (mainly) men born in 1928-1953 received a questionnaire. Of the respondents (32%), eligible subjects were invited to participate (19%). Fifty-five percent gave informed consent and was randomised. Background characteristics were compared between male respondents on the first questionnaire (n = 92,802), eligible subjects among them (n = 18,570) and those randomised (n = 10,627) and Statistics Netherlands 2002-2005 (SN) (n = 5289) or GLOBE study-data (Dutch cohort) (n = 696). Initial respondents were less likely to be highly educated (OR(adj) = 0.84; 95% CI: 0.74-0.96) and comprised of significantly less current smokers (OR(adj) = 0.65; 95% CI: 0.61-0.69) compared to the general population. These current smokers smoked more heavily (OR(adj) = 1.23; 95% CI: 1.10-1.37), but for a shorter time-period (respondents: 31, SN: 42 years, p < 0.001). Age, general health, BMI, alcohol use and cancer prevalence were comparable. The randomised population was younger (Age 50-65) (randomised subjects: 85.3%, SN: 72% (p < 0.01)) comprised of more heavy current smokers (OR = 2.08; 95% CI: 1.75-2.44), that smoked for a shorter period of time (randomised subjects: 37, SN_selection: 42 years (p < 0.001)). Both the respondents (32%) of the first questionnaire as well as the randomised population of the NELSON trial appeared to differ slightly on smoking characteristics, but the differences were limited and probably balance each other. Results of the NELSON trial will be roughly applicable to the Dutch and probably other populations that fulfil our selection criteria.

Overweight and obesity in infants and pre-school children in the European Union: a review of existing data.

The objective of this study was to synthesize available information on prevalence and time trends of overweight and obesity in pre-school children in the European Union. Retrieval and analysis or re-analysis of existing data were carried out. Data sources include WHO databases, Medline and Google, contact with authors of published and unpublished documents. Data were analysed using the International Obesity Task Force reference and cut-offs, and the WHO standard. Data were available from 18/27 countries. Comparisons were problematic because of different definitions and methods of data collection and analysis. The reported prevalence of overweight plus obesity at 4 years ranges from 11.8% in Romania (2004) to 32.3% in Spain (1998-2000). Countries in the Mediterranean region and the British islands report higher rates than those in middle, northern and eastern Europe. Rates are generally higher in girls than in boys. With the possible exception of England, there was no obvious trend towards increasing prevalence in the past 20-30 years in the five countries with data. The use of the WHO standard with cut-offs at 1, 2 and 3 standard deviations yields lower rates and removes gender differences. Data on overweight and obesity in pre-school children are scarce; their interpretation is difficult. Standard methods of surveillance, and research and policies on prevention and treatment, are urgently needed.

Intra-national variation in trends in overweight and leisure time physical activities in The Netherlands since 1980: stratification according to sex, age and urbanisation degree.

OBJECTIVE: To investigate time trends in overweight and Leisure Time Physical Activities (LTPA) in The Netherlands since 1980. Intra-national differences were examined stratified for sex, age and urbanisation degree. SUBJECTS AND METHODS: We used a random sample of about 140,000 respondents aged 20-69 years from the Health Interview Survey (Nethhis) and subsequent Permanent Survey on Living Conditions (POLS). Self-reported data on weight and height and demographic characteristics were gathered through interviews (every year) and data on LTPA were collected by self-administered questionnaires (1990-1997, 2001-2004). Linear regression analysis was performed for trend analyses. RESULTS: During 1981-2004, mean body mass index (BMI) increased significantly by 1.0 kg/m(2) (average per year=0.05 kg/m(2)). Trends were similar across sex and different degrees of urbanisation, but varied across age groups. In 20-to 39-year-old women, mean BMI increased by 1.7 kg/m(2), which was more than in older age groups (P

Trends in socioeconomic health inequalities in the Netherlands, 1981-1999.

STUDY OBJECTIVE: To determine changes in socioeconomic inequalities in self reported health in both the 1980s and the 1990s in the Netherlands. DESIGN: Analysis of trends in socioeconomic health inequalities during the last decades of the 20th century were made using data from the Health Interview Survey (Nethhis) and the subsequent Permanent Survey on Living Conditions (POLS) from Statistics Netherlands. Socioeconomic inequalities in self assessed health, short-term disabilities during the past 14 days, long term health problems and chronic diseases were studied in relation to both educational level and household income. Trends from 1981 to 1999 were studied using summary indices for both the relative and absolute size of socioeconomic inequalities in health. SETTING: The Netherlands. PARTICIPANTS: For the period 1981-1999 per year a random sample of about 7000 respondents of 18 years and older from the non-institutionalised population. MAIN RESULTS: Socioeconomic inequalities in self assessed health showed a fairly consistent increase over time. Socioeconomic inequalities in the other health indicators were more or less stable over time. In no case did socioeconomic inequalities in health seemed to have decreased over time. Socioeconomic inequalities in self assessed health increased both in the 1980s and the 1990s. This increase was more pronounced for income (as compared with education) and for women (as compared with men). CONCLUSION: There are several possible explanations for the fact that, in addition to stable health inequalities in general, income related inequalities in some health indicators increased in the Netherlands, especially in the early 1990s. Most influential were perhaps selection effects, related to changing labour market policies in the Netherlands. The fact that the health inequalities did not decrease over recent years underscores the necessity of policies that explicitly aim to tackle these inequalities.

[Complete dentures in the Dutch population 1981-1992]. / Gebitsprothesen bij de Nederlandse bevolking 1981-1992.

In the period 1981-1992 the percentage of people with a full set of dentures dropped from 31.6 to 22.5 in the Netherlands (persons > or = 16 years). This is particularly due to the relatively strong decrease in the number of young people with full dentures. Regional differences are remarkable: in the northern provinces the percentage is relatively high; in the province of Utrecht it is relatively low. Recently regional differences appear to be (very) small among the young age groups. Many people with a full set of dentures use the same dentures for a long period: about 20% of them have had their current prostheses for 16-25 years, another 20% for over 25 years. Taking into account the total adult population, it appears that the socio-economic status (SES) negatively correlates with the probability of having a full set of dentures. This holds for all three SES indicators in the study: education, income and type of insurance. But among the young age groups this correlation is only valid for education.