Study design

The Netherlands Epidemiology of Obesity (NEO) study is an ongoing population-based prospective cohort study. Between 2008 and 2012, 6,671 individuals aged 45–65 years at baseline have been included.


Obesity is a well-established risk factor for many chronic diseases. The NEO study is designed to investigate pathways that lead to disease in obesity. The main clinical endpoints of the NEO study are: 

  • Type 2 diabetes
  • Cardiovascular diseases
  • Venous thrombosis
  • Chronic kidney disease
  • Asthma 
  • Chronic obstructive pulmonary disease (COPD)
  • Osteoarthritis
  • Cirrhosis
  • Depression
  • Mortality 

Study population and recruitment

Between September 2008 and October 2012, 6,671 men and women living in the greater area of Leiden participated in the NEO study. 

Men and women were eligible to participate in the NEO study when they were  45 to 65 years of age and had a self-reported BMI of 27 kg/m2 or higher. 

In addition, all inhabitants aged 45 to 65 years from the municipality of Leiderdorp were invited irrespective of their BMI, to allow for a reference distribution of BMI. 

Participants were recruited via three recruitment strategies:

  1. Via general practitioners in the area of Leiden
  2. Through advertisements in local newspapers and through posters distributed in public areas
  3. Via the registers of three municipalities surrounding Leiden (Katwijk, Leiderdorp and Teylingen)

Baseline measurements

The baseline data collection took place between 2008 and 2012. At baseline the participants completed questionnaires at home and visited the NEO study center for an extensive physical examination. Additional information about the participants’ medical history at baseline was obtained through the electronic patient records of their general practitioner. 

Detailed descriptions of the NEO baseline study design, methods and collected data are available under Baseline measurements.

Follow-up questionnaire 

Between 2012 and 2014, 5228 NEO participants completed a short follow-up questionnaire, including questions about weight, waist circumference, health and quality of life (QOL). More information is available under Follow-up questionnaire.

Collection of clinical endpoints during follow-up

The NEO study participants are followed for the collection of clinical endpoints through the electronic patient records of general practitioners. In the future the NEO study will also be linked to hospital admission databases and the Central Bureau of Statistics Netherlands (CBS) for information on vital status and causes of death. Study participants gave informed consent for the collection of medical information from these sources.

For more information about the collection of clinical endpoints for follow-up, see Collection of clinical endpoints.

For more detailed information about the NEO study design and methods: de Mutsert R, den Heijer M, Rabelink TJ, Smit JW, Romijn JA, Jukema JW, de Roos A, Cobbaert CM, Kloppenburg M, le Cessie S, Middeldorp S, Rosendaal FR. The Netherlands Epidemiology of Obesity (NEO) study: study design and data collection. Eur J Epidemiol 2013;28:513-523

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