The Netherlands Mental Health Survey and Incidence Study‐3 (NEMESIS‐3): Objectives, methods and baseline characteristics of the sample

Abstract

Objectives: NEMESIS-3 (Netherlands Mental Health Survey and Incidence Study-3) is a psychiatric epidemiological cohort study of the Dutch general population that replicates and expands on two previous NEMESIS-studies conducted in 1996-1999 and 2007-2018 respectively. The main aims of NEMESIS-3 are to provide up-todate information on the prevalence, incidence, course and consequences of mental disorders, their risk indicators, and to study the relevant time trends. This paper gives an overview of the objectives and methods of NEMESIS-3, especially of the recently completed first wave, and describes the sample characteristics. Methods: NEMESIS-3 is based on a multistage, stratified random sampling of individuals aged 18-75 years. Face-to-face interviews were laptop computer-assisted and held at the respondent's home. A slightly modified Composite International Diagnostic Interview (CIDI) version 3.0 was used to assess both Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) and DSM-5 mental disorders. Two follow-up waves are planned three and six years after baseline.Results: In the first wave, performed from November 2019 to March 2022, 6194 individuals were interviewed: 1576 respondents before and 4618 respondents during the COVID-19 pandemic. The average interview duration was 91 min and the response rate was 54.6%. The sample consisted of 50.4% women and had a mean age of 47.9 years. The sample was reasonable nationally representative, although some sociodemographic groups were somewhat underrepresented.Conclusions: Despite the COVID-19 restrictions, we were able to build a large and comprehensive dataset of good quality, permitting us to investigate the latest trends in mental health status, various new topics related to mental health, and the extent to which the pandemic has had an effect on the population's mental health.

Prevalence and trends of common mental disorders from 2007‐2009 to 2019‐2022: results from the Netherlands Mental Health Survey and Incidence Studies (NEMESIS), including comparison of prevalence rates before vs. during the COVID‐19 pandemic

“…To allow generalization of the data to the Dutch population, based on post‐stratification, a weighting factor was constructed for each study. After weighting, the distribution of the socio‐demographic characteristics of both study samples was very similar to that of the Dutch population in the particular study period 34,35 .…”

“…The significant increase in the prevalence rates of mental disorders over time cannot be attributed to the small difference in clinical assessment instrument between NEMESIS‐3 and NEMESIS‐2, as in both studies the DSM‐IV diagnoses were based on the same questions using the same algorithms. The increase is also not caused by the fact that 500 interviews (8.1%) were conducted via video calling in NEMESIS‐3, as those interviewed via video calling did not differ in 12‐month and lifetime prevalence rates from those interviewed face‐to‐face, after adjustment for socio‐demographic differences between the two groups 34 . Change in the population structure, such as relatively more highly educated people and more people with a paid job, also does not explain the sharp increase in prevalence of mood and anxiety disorders, but it may have played a limited role in explaining the increase in substance use disorders.…”

“…This is a fully structured diagnostic interview, developed for use in the World Mental Health Survey Initiative 39 . In NEMESIS-3, a slightly modified version of CIDI 3.0 was used to enable both DSM-IV and DSM-5 diagnoses 34 .…”

“…Most DSM-5 definitions of mental disorders are based on information already available in the CIDI 3.0, and were applied by making small changes in the algorithms 34 . However, to enable the assessment of ADHD according to DSM-5 criteria, the childhood symptom questions referred to their presence prior to age 12, instead of age 7 as in the DSM-IV.…”

“…In NEMESIS-3, the same questions and measurement methods as in NEMESIS-2 were used, to enable comparisons 34,35 .…”