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The 1915 Birth Cohort Study


The demographic change towards an increasing proportion of old and oldest old people in industrialized societies is well known.  The past decades of declining birth rates and improved survival among older people are the major driving forces.

An important aspect of this study is to determine the overall health profile and functional ability of the current population of long-lived individuals.


To compare morbidity and physical and cognitive health of three different birth cohorts aged 100 years.

Materials and Methods

The 1915 birth cohort was first surveyed in 2010, when they were 95 years old. The second wave has been conducted in 2015, and comprised individuals who lived to celebrate their 100th anniversary. At this  age the 1915 birth cohort was divided into two geographic parts: the "1915-West" defined as the country west of the Great Belt, and the "1915-East" defined as the eastern part of the country. Overall, we will compare the 1915 cohort to both the 1895 birth cohort and the 1905 birth cohort, which will enable us to compare centenarians living 20 years apart.

All centenarians (age 100) were identified through the Danish Civil Registration System (CRS). In total, 502 individuals born in 1915 turned 100 years old in 2015.

All interviews were carried out in the participants’ own home, but with two different survey methods as described below.

The “1915-East”: Trained lay interviewers from the Danish Institute of Social Research collected data during the period from August to November 2015. The survey comprised two parts: (1) a comprehensive questionnaire containing information about socio-demographic variables, health, self-reported ADL, social network, interests, smoking and drinking habits. (2) A clinical assessment including a test of depression and cognition, physical tests, blood pressure and lung function. No blood samples were collected.

In “1915-West”: Data was collected by a medical doctor and a research nurse and the visits were carried out continuously as the participants turned 100 years old. The visits took place from January 2015 to the beginning of February 2016. The survey was almost identical to the survey in “1915-East” and comprised a comparable questionnaire and all the same examinations. Only the clinical assessment was expanded further to also include spirometry, electrocardiogram (ECG) and echocardiography. Blood samples were collected by venipuncture.

Study Design

The design is a longitudinal cohort study. Inclusion criteria:  All persons born in 1915, alive on their 100th birthday, and living in Denmark. There were no exclusion criteria and proxy interviews were allowed.

Time Frame

From September 1st 2014 to august 31st 2017


The Velux Foundation, the Novo Nordisk Foundation and SDU Faculty of Medicine.

Main Supervisor


  • Associate professor, Sabine Gill, Dept. of Cardiology, Odense University Hospital
  • Professor Kaare Christensen
PhD Student

Signe Hoi Rasmussen


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Birth cohort 1915