Saturday, December 15, 2007

Prevention of unnecessary weight gain at the worksite

Yesterday Lydia Kwak defended her PhD thesis at a public meeting at Maastricht University. Her thesis describes the development, implementation and evaluation of an intervention program aiming to contribute to prevention of unnecessary weight gain among employees. Her PhD research was part of the NHS-NRG project, a comprehensive project funded by the Netherlands Heart Foundation on obesity prevention. This project consisted of two studies exploring behavioural, cognitive and environmental determinants of weight gain and energy-balance related behaviours, and three intervention studies; one aimed at adolescents (the Do-IT intervention), one for elderly people (the WAAG-study), and the one Lydia used for her PhD thesis which was called the In-Balance study.
Lydia Kwak used the Intervention Mapping protocol to develop the intervention that consisted of health education, self monitoring and environmental change components. The evaluation study used a controlled design and the results indicated that employees in intervention worksites had a lower fat mass at follow-up than employees of control worksites where the intervention program was not implemented. Her studies also showed the difficulties to convince worksites to participate in such an important study and to convince employees to participate in weight gain prevention activities. Prevention of weight gain should be key in attempts to curb the obesity epidemic, since treatment of obesity is hardly ever successful on the loner run.
Lydia Kwak’s thesis studies have been published in different international scientific journals. See for example:

Sunday, December 9, 2007

How can we evaluate national health promotion campaigns?

In the Netherlands as in many other countries, we invest in promotion of healthful and safe behaviours to contribute to prevention of chronic disease, accidents, et cetera. One of the ways to contribute to promotion of healthy lifestyles are so-called national campaigns, that often make use of mass media to communicate health promotion messages to the population at large.

Such campaigns should be evaluated to study if these campaigns indeed contribute to more healthful lifestyles among the population, i.e. we should study if money and other resources allocated to such campaigns are well spend.

A valid evaluation of national campaigns is not easy. The strongest research design to evaluate the effects of interventions is the so-called randomized controlled trial (RCT). RCTs are considered the most reliable form of scientific evidence in healthcare because they eliminate spurious causality and bias. RCTs are mainly used in clinical studies, but are also employed in other sectors such as judicial, educational, and social research. As their name suggests, RCTs involve the random allocation of different interventions (or treatments) to subjects or respondents/participants. This ensures that confounding factors are evenly distributed between treatment groups.

However, in evaluation of national campaigns randomization is not possible and a control group is not available because the population at large is exposed to the intervention.

Many national campaigns are therefore evaluated by means of a very simple design with one before and one after measurement. This often means that before and after the campaign is launched a sample of the target population is surveyed on the behaviour the campaign is addressing. If the after-campaign survey shows better results, this is supposed to indicate that the campaign was successful. The weakness of this research design can be illustrated with an example. The first picture next to this blog message shows the results of such before and after campaign measures related to the introduction of a bicycle helmet law in Australia. Before wearing a helmet became compulsory the number of head injuries was much higher than after. Conclusion: making people wear helmets prevents head injuries!? The second picture shows that this was not the case. In this picture not one before and one after campaign measurement was used, but a whole series of before and after measurements. This is called an interrupted time-series design. This picture shows that the reduction in head injuries was already ongoing before the helmet law was introduced, that this downward trend was continued after the law was in place. The picture indicates that the law did not change this trend in any way. Conclusion: the bicycle helmet law had no effect at all on head injuries.

The interrupted time series design is generally regarded as best-practice in evaluation of national campaigns or other circumstances where a control group is not possible. The Dutch Health Council recently published an advice on evaluation of national campaigns in which this was confirmed ( However, such an interrupted time-series design requires careful and timely planning of evaluation, additional resources to do the extra measurements, and expertise for statistical analyses of time series data. Time, extra resources and specialized statistical expertise is not always available for the organizations that develop and implement the campaigns, and these organizations feel that interrupted time-series design may be the best but not a realistic option for them. Furthermore, evaluation of national campaigns may not always need to be concerned with effects in terms of lifestyle behaviour changes, but sometimes evaluation in terms of reach, adoption, implementation or maintenance (see RE-AIM framework, of campaign activities may be sufficient, and such evaluations may require different research designs.

The Netherlands Organisation for Health Care Research and Development, ZonMW ( has ask me to further explore best and realistic practice in evaluations of national campaigns in the Netherlands. In the few months interviews will be held with representatives of all the organizations in the Netherlands that organize and implement national campaigns to learn about their evaluation goals, barriers and wishes for improvements.

Sinterklaas day with the Board of the VU University Medical Center

Five December is Sinterklaas day in the Netherlands (see for detailled information in Ducth, and for information in English). Sinterklaas or Sint Nicolaas (Saint Nicolaus) was a bishop from Myra in present day Turkey during early Christianity. His remains were abducted to Bari in southern Italian where a very beautiful Roman Sinterklaas church can be found. But the Dutch Sinterklaas legend tells us that Sinterklaas comes from Spain to the Netherlands with his ‘Moor’ servants (‘Zwarte Pieten’), bringing all children who have been good presents and treats. The story goes that the Coca Cola company adopted this wonderful celebration, transferred it to Christmas, and created Santa Claus, a kind of weak and stupid looking cousin of the real Sinterklaas.
This year I spend Sinterklaas day and night in the castle-hotel Vanenburg ( The board of the VU University Medical Center ( had invited the heads of the six Divisions to discuss such issues as the VUmc’s mission, the key stakeholders that the VUmc wishes to serve, and necessary human resource management to fulfil the mission.
For me it was a great opportunity to get to know the chairs of the other Divisions a little better and to join in fruitful discussions on VUmc’s ambitions (yes, we do wish to get better in what we do in health care, education and research) and the way we wish to realise these ambitions.