“Our goal is personalized prevention”

In May 2019 the second round of examinations in the German National Cohort (GNC) health study got underway at the MDC. Tobias Pischon, an MDC researcher and a member of the GNC board of directors, explains why additional data are so important to the success of the long-term study.

Professor Pischon, you are head of the GNC’s Berlin-North study center at the MDC, where since 2014 data have been collected from a total of 10,000 people. Some 200,000 people nationwide are participating in the GNC and they will be studied over several decades. What is the aim of the study? 

We want to analyze the risk factors of the most common chronic diseases – such as diabetes and cardiovascular diseases. Our hope is to be able to identify new risk factors and to discover new biomarkers: Who has a high disease risk and who doesn’t? So far only imprecise predictions have been possible. Our goal is personalized prevention. We therefore want to predict as precisely as possible the risk for individual patients.  

What does this entail in concrete terms? What data are you collecting and how are these data being interpreted? 

Let’s take sports as an example. We know that physical activity generally reduces the risk of developing various chronic diseases. But we don’t know which type of sport and which intensity of training is healthy for certain people. GNC participants are required to wear an accelerometer for seven days straight without interruption. The device captures all movements including acceleration in all three spatial axes, thus enabling us to construct a detailed physical activity profile. Since we will be collecting these data repeatedly from a very large number of people, we will be able in the future to draw conclusions about how a type of sport can affect individual health. 

The second round is now underway; all participants will be examined again. What are you trying to learn? 

We generally stay in contact with study participants. They are asked to fill out questionnaires every two to three years. We want to find out, among other things, if there is new incidence of disease among the participants. Every participant is invited for a complete re-examination after five years. The examinations by magnetic resonance imaging (MRI) are also repeated; the MDC has conducted 6,000 such examinations. The purpose of these is to study, for example, changes in the thickness of heart walls, where anomalies are often present in healthy people. The significance of these anomalies is unclear: Are they normal variants or are they in fact pathological? The repeat examinations allow us to see how these images have changed and whether they can perhaps be associated with the emergence of diseases. 

Prof. Dr. Tobias Pischon

Is there a research question that especially interests you? 

There are several. Such as the question of to what extent obesity is a risk factor for sequelae. Severely overweight men frequently suffer from high blood pressure or dyslipidemia. But this is not true in all cases: Some obese people become sick while others don’t. This has led to the assumption that there might be a “healthy” type of obesity. I, on the other hand, think that obesity is a risk factor for future diseases in all cases and assume that we will find evidence to support this. I am also excited about the question of what results geocoding will produce. The analysis results do not include the exact addresses of the participants, but they are assigned to regions. That means we can evaluate how environmental changes – such as fine particulate and noise pollution or changes in climate – affect health. 

When will you begin to analyze the data? 

We have already started to organize the data. However, this initially involves only data description and not analysis. The results of the basic data set – half of the data will be analyzed initially, i.e., data from 100,000 first-phase examinations and 15,000 MRI examinations – will be available in late 2019. The GNC, however, will not analyze the data itself, but various groups of experts – also ones at the MDC – will submit proposals for research projects that will investigate certain questions more closely.  

You expect that around 70 percent of participants will undergo a second examination. Why are these follow-up examinations, which are about to start, so important to the study? 

The GNC’s scientific value is based precisely upon its prospective character: The examinations at five-year intervals and the additional monitoring of the participants’ state of health enable us to measure changes and evaluate them later.  

I will gladly give another example of why this is so beneficial. In the case of high blood pressure, there is a critical value at which the risk for sequelae becomes very high. It is a similar situation with diabetes, where patients are considered to be sick once their blood sugar level exceeds normal limits. But less elevated values might also adversely affect health. Or there may be parameters that represent a risk factor but haven’t been taken into consideration so far. Take for example waist circumference: Several years ago in the EPIC study we learned that it is a critical factor for cardiovascular diseases. By adjusting threshold values or by taking new influencing factors into account, we hope in the future to be able to begin prevention earlier or use other measures and thus avoid diseases. 

Wiebke Peters conducted the interview.