Interview on the SHIP study in North Western Pomerania with Prof. Dr. Ralf Ewert

Prof. Ewert, the SHIP study is a large epidemiological study. What exactly is being investigated in the SHIP study and what does the name mean?

SHIP stands for “Study of Health in Pomerania”. Epidemiological study means that the study is carried out on the normal population. In this case in North Western Pomerania (NWP), a region in northeastern Germany near Usedom, Rügen and Poland. This region is sparsely populated with around 200,000 inhabitants. 

There are two reasons why the NWP region was chosen for the study: After German reunification, the German Council of Science and Humanities noticed during an assessment and selection of priorities for all German universities that the NWP region, which is described as economically and socio-culturally poor, has two to three special features. On the average, the inhabitants are five years older than the national average. 

In the early 2000s, nearly 35% of the population in NWP was over 65 years old. The scenario of how things will look in 20 or 30 years in Germany as a whole is already a reality in NWP. 

The second reason is the number of risk factors occurring in this region: Obesity, high blood pressure, lipometabolic disorders, smoking and alcohol consumption. 

The Science Council recommended, based on these findings, conducting a survey of a cross-section of the population, to be repeated every five years. The goal is to detect early changes in health in order to learn what the early stages of chronic diseases look like – especially cardiovascular diseases. This experience is to be incorporated into an early diagnosis for the entire population. This was the reason for the launch of the first SHIP-START study in 1997.

A sample of approximately 11,000 people aged between 20 and 80 was taken from the current residents’ register in NWP. This selection allows an evaluation and statistics in relation to the total population. Around half of those surveyed – 5,000 people – have since taken part in the study every five years. Repeating the examination is intended to detect and diagnose diseases in their early stages. 

At the heart of the study – similar to a standard health check-up – is the clinical examination of height, weight, blood tests, blood pressure, hearing, vision, dental health, and more. A key feature is the comprehensive examination using MRI¹ imaging. The study participants are examined from head to toe using imaging techniques. All examinations are voluntary. This modern procedure examines the entire body.

That’s interesting – how is such a large study funded?

The funding for the main project, known as the CORE project, comes from public sources – the Federal Ministry of Education and Research (BMBF), as well as funds from the state and other organizations. 

In addition to the main project, there are smaller, associated projects that are offered to participants as an optional supplement. In cardiology, for example, an ultrasound examination of the heart is performed as part of the main project. A stress test is also offered within the study. This is funded by the pulmonary department itself, through third-party funds or research grants that need to be secured. 

The modern MRI examination is funded by a medical equipment manufacturer. 

Federal support has decreased over the past 20 years, while the costs of the SHIP study have increased. These include rising costs of personnel, diagnostic technology, equipment, and consumables. As project coordinators, we secure these funds in order to carry out the projects. 

One problem is that the study loses participants due to mortality among the elderly or relocation to other federal states or abroad (especially among the younger ones). 

An important quality criterion for epidemiological studies is to achieve a high responder rate. This is the percentage of participants who are recruited for the follow-up examination after five years. Recruiting these participants is part of our work. Supportive activities include press work to inform participants and their employers. Ultimately, the assessments span two full days. Participants receive time off work, compensation for lost wages, a €50 allowance, and a travel cost subsidy, among other things.

What is the scientific significance of sleep medicine within the SHIP study?

Sleep medical examination did not yet exist when the SHIP study started in 1997. There were only questions about sleep habits, sleep duration, and subjectively perceived sleep disturbances. It was only during the 2000s that the importance of sleep medicine disorders as a potential risk factor for cardiovascular diseases came into the scientific spotlight. 

A new SHIP-TREND study, the second one, was first launched in 2008, with a sleep medicine complex. This includes questions on sleep quality, sleep duration, possible influencing factors such as shift work, chronic illnesses, and a comprehensive evaluation of medications, since many drugs can either promote or disrupt sleep. 

From 2008-2012, an overnight polysomnographic examination was carried out. The assessment included EEG, breathing flow, and evaluation of Restless Legs Syndrome. A special feature was that the overnight stay took place in a hotel in Greifswald. Participants stayed overnight in a comfortable hotel room, where a detailed sleep examination took place. 

Around 1,300 of the 4,300 participants in the SHIP-TREND study have volunteered for this study to date. For the study, this was an innovation in Europe back in 2008, as very few epidemiological studies across Europe had conducted such an examination at that time.

For the SHIP-TREND study, the combination of sleep medicine assessments with interviews and modern MRI imaging is a unique feature.

The analysis of the collected data – through collaboration with sleep specialists, neurologists, psychiatrists, and MRI experts – enabled extensive research into brain changes, EEG abnormalities, and sleep disorders. The results at least support the strong suspicion that sleep disturbances at night are indeed a relevant cardiovascular risk factor. In particular, the insufficient breathing depth and the breathing interruptions. 

It is already known that breathing interruptions increase cardiovascular risk, which can lead to stroke, high blood pressure, and heart attack. That has already been known from patient examinations for some time. 

What we have now newly discovered is that the decreasing blood oxygen saturation (hypoxemia) caused by breathing pauses and shallow breathing is associated with an increasing incidence of dementia. 

The consequences of the breathing disorder have a very high likelihood of being one of the triggering factors for dementia. There is a clear correlation between the age-related increased occurrence of memory and functional disorders in the brain and the increasing frequency of oxygen desaturation in the blood in sleep disorders. 

If we include all degrees of severity of sleep disorders, we have 40 percent of the population of both sexes aged 50 who have something like this. That is a very high figure. Sleep disorders start in men from the age of 40 and in women usually from the age of 50 after the menopause. Increased body weight is an amplifier for both sexes. We depend on follow-up studies to illustrate the relationship. 

We are gaining new insights and support through international cooperation with neurologists and sleep medicine specialists from international studies. We have developed a SHIP study in Brazil, similar to SHIP-START. It is quite interesting to see how the people develop in the community of Pomerode² in southern Brazil. They are genetically connected to the people in NWP. 

In a third independent cohort, in 2019 at SHIP-START, we began to conduct the sleep study in two ways. Modern smart wristwatches, so-called wireless devices or wearables, which can be used to examine sleep algorithms, are used in parallel with a nocturnal polysomnography examination (PSG). The aim is to find out whether the standard PSG examination provides significantly more and better insights. After all, the trend – especially among younger people – is towards achieving maximum results with simpler devices and minimal wiring, while obtaining comparable data. As a result, we continue to offer the standard PSG examination in a very complex form. 

The perception of sleep disorders has become much higher than it was 15 years ago. Between 2008 and 2012, we were able to count 1,300 volunteers for the sleep study. In the current study, we have already examined 1,600 volunteers after four years. Many more test subjects voluntarily choose this sleep complex! The currently ongoing sleep examination is conducted using state-of-the-art technology. The voluntary sleep examinations take place in our Greifswald hotel with a study sleep laboratory, following standardized procedures and conducted by certified and trained examiners. Using the most advanced technology currently available on the market.

When the current round of examinations is completed (in the first quarter of 2026), we will invite those participants who were with us between 2008 and 2012 to return in the fourth quarter of 2026 or the first quarter of 2027. That is a period of around 15 years after the first examination. Then we will monitor their development and carry out all examinations, including laboratory tests and imaging. The study with wearables is running parallel. The collected results are reviewed and, if necessary, repeated.

The polysomnographic devices from Löwenstein are being used in the current study. The raw data from the devices is extracted, analyzed, and evaluated for scientific research purposes. I coordinate the associated projects that have to do with pulmonary medicine and partly with performance diagnostics, because I represent the departments of pulmonary medicine, performance diagnostics and infectiology in the clinical area. The sleep project is clinically represented by me. We offer the study participants the opportunity to undergo a sleep medicine examination. I coordinate these individual examinations. In the overall network with other international studies, of course.

I see myself as a scientist who researches with heart and passion. We are working in the field of clinical research and not in the laboratory. I take a very positive view of this. Because it’s always about people.

I’ve been involved since 2001. This work is only possible with an interdisciplinary team made up of biosignal researchers, biomathematicians, documentation specialists, medical professionals, statisticians, methodologists, analysts, and others. Around 100 people work on the studies in Greifswald. There is also an independent scientific advisory board and data structure analysis unit (data transfer office).

How exactly are the sleep medical examinations carried out in the SHIP study?

The study is conducted at the central examination center at the University of Greifswald. The questionnaires are completed here. Standardized interviews are conducted by certified professional interviewers, along with the central examinations. 

In addition to the standard examinations, test subjects can choose from a range of examination packages. This also includes the nocturnal sleep examination in the study sleep laboratory. 

The participant is entered into a registration list and assigned an anonymized ID. No names are communicated. The number is used to invite them to the overnight study. There are four study sleep places available per night at the hotel. The sleep examination takes place up to five days per week. 

The sleep medicine examination takes place outside the hustle and bustle of university life, in a quiet, hotel-like building. The technology for the nocturnal sleep examination is housed in four comfortable rooms. The remaining four rooms in the building are dedicated to regular hotel operations. 

In a monitoring room, trained, mostly medical students monitor and control the sleepers and their currents at night, which are recorded (brain wave curves, ECG, leg movements, etc.). If there is a signal loss (caused, for example, by a trip to the bathroom), the staff ensure that the electrodes are reattached and the signal recording continues. Consistent recording of the data must be guaranteed. 

The evening before, the test subjects are wired up in a complex procedure. After six to seven hours of sleep, the test subjects go home or to work. This is followed by data analysis, which is carried out by specialized employees in accordance with an international standard. The data is then stored on the server, encrypted again, and transferred anonymously to the examination center. 

The special feature of the SHIP study is that the methodology is designed in such a way that potentially clinically relevant or even life-threatening findings are communicated to the test person. In sleep medicine, this means that if a diagnosis of moderate to severe obstructive sleep apnea syndrome is made, the participant is notified via the data transfer office. This is accompanied by an offer to contact a sleep specialist or to have the findings forwarded to the participant’s general practitioner.

Can you already tell us the initial results of these investigations or is it still too early?

We know from the last study that sleep-associated breathing disorders³ occur more frequently in men aged 40 and over and in women aged 50 and over, the older the test subjects are. We diagnose this type of sleep disorder here. 

Upon reaching the age of 60, men and women exhibit these disorders with equal frequency. 

Equally frequent means that relevant sleep disorders occur in the healthy population. This includes more than 15 events of insufficient or interrupted breathing per hour. A moderately severe disorder begins from a measured value of 15. From this value, it is clinically relevant. In fact, in some age groups there are 30% or up to 40% of test subjects with sleep disorders. I would like to stress that this is a sample from the healthy population. 

In the assessment of these sleep disorders, they are not generally classified as a clinical syndrome until symptoms are present. These are daytime sleepiness, tendency to fall asleep, headaches, concentration disorders and memory disorders, which can be associated with the measured respiratory disorders. Only when both come together – sleep-related disorders and the aforementioned symptoms – is it called sleep apnea syndrome. 

Here, too, there are certain limits that are internationally accepted. The combination of measured sleep disorders and symptomatology is significantly less frequent in the normal population. We are talking about 4-6%. In translation, this means that four to six out of every 100 healthy people, that is one in 20, have a pathological, sleep-associated breathing disorder that requires treatment. That is very high.

Will the SHIP study be continued or is there a follow-up project?

We all hope that it will be continued. The SHIP study is planned for the next ten years. There is much to suggest that it will be continued in the longer term. Like the cardiovascular Framingham Heart Study in the USA⁴, which has been running since the late 1940s, we hope that it will continue.

One indication of the continuation of the SHIP study is the new research building – the William B. Kannel Center for Community Medicine (CM). Supported 50 percent by federal funds and the remainder by state funds, the new research building receives additional federal support beyond state funding due to its special significance. We celebrated the topping-out ceremony at the turn of the year. Completion will take place in 2026. The sleep medicine laboratory will also move there. Four spaces will be created on the fourth floor. The follow-up study of SHIP-Trend (2008-2012) is expected to take place in the research building in 2027. In other words, these are people who are now 15 to 20 years older. It will also house all the other research areas, which are currently spread throughout the city. 

If you look at the primary approach, that we want to find early symptoms for later diseases, it follows an internal logic that the study will continue for many decades. We all strive for this and work to secure the necessary funds. Output in the sense of scientific cooperation with other studies, but also scientific publications as a result of this research. In the end, it enhances the benefits for the participants. In a positive scenario, if a patient visits a doctor in 20 years due to sleep disorders, their electronic health record will note that, at age 35, they already had 20 breathing interruptions as a participant in the SHIP study.

Since the study is publicly funded, anyone interested worldwide is allowed to submit an application to access the data. For this purpose, a data usage application must be submitted on the SHIP study website. 

Thank you very much, Professor Ewert