Design LASA

Design of the LASA Study

The LASA Study is a prospective cohort study of older adults in the Netherlands, initially based on a nationally representative sample of people aged between 55 and 85 years. The study has been ongoing since 1992, and focuses on the determinants, trajectories and consequences of physical, cognitive, emotional and social functioning. Strengths of the LASA study include its multidisciplinary character, the availability of over 25 years of follow-up, and the cohort-sequential design that allows investigations of longitudinal changes, cohort differences and time trends in functioning.

Objectives
LASA is designed to be an interdisciplinary, longitudinal study on aging. Besides a strong academic basis, the study should provide opportunities for developing and evaluating (central and local government) policy in the field of aging. These principles guide the selection of measurements and data that is available from the LASA study.

LASA’s main topics of interest are aspects of daily functioning, older persons’ evaluation of functioning, social participation and care. Four components of functioning are distinguished: physical, cognitive, emotional and social functioning. Examples of measures of functioning that are included in the LASA database are: disability and physical performance, general cognitive functioning, depression and mastery, loneliness and social participation. Because LASA includes data about these multiple components of functioning, the data is especially useful for investigating cross-component associations.

Key characteristics of the study

  • Cross-sequential longitudinal study
  • Multidisciplinary approach
  • Nationally representative sample
    obtained from registries of 11
    municipalities     (now 9
    municipalities) across 3 culturally
    distinct regions in the Netherlands
    (see map)
  • Initial ages 55-84
    • N (cohort 1) = 3,107 (1992)
    • N (cohort 2) = 1,002 (2002)
    • N (cohort 3) = 1,023 (2012)

Measurement and observation cycles (waves)
Data collection started in 1992-1993 among a cohort of respondents aged 55-84 years old (N=3,107, wave B, baseline). Since then, measurement cycles have been conducted about every three years. Measurements are performed by trained interviewers, who visit respondents at home. Usually two separate interviews are conducted: a main interview and a medical interview, with clinical measurements. Also, respondents are asked to fill out a questionnaire.

So far, observation cycles for this first cohort (cohort 1) took place from 1992-1993 (wave B, baseline) until the latest in 2018-2019 (wave J, see Table 1). An additional cohort of respondents aged 55-64 years was included from the same sampling frame and was measured for the first time exactly ten years after the original baseline measurement, in 2002-2003 (cohort 2, N=1,002, wave 2B). Since then, respondents from this second cohort of respondents have been included in regular LASA measurement waves.

In 2012-2013, exactly twenty years after the baseline measurement, a third cohort study (cohort 3, wave 3B) was initiated with new respondents aged 55-64 years from the same sampling frame. This sample has also  been included in regular LASA measurement waves. So, the measurement waves in 2015-2016 (wave I) and 2018-2019 (wave J) have been executed containing respondents from cohorts 1, 2, and 3. Note that the Migrant cohort (MB) which was examined in 2013-2014 has its own sampling frame. Up to March 2020, most of the data of wave I have been processed. Data collecting of wave J has been finished in March 2020 and most of the processing work on these data was finished in the course of 2021.

In the second half of 2021  a new wave (K, 2021-2022) was done with again respondents from cohorts 1, 2 and 3.

LASA measurement cycles (waves) 1992-2022

Wave


Year


Total N		B


1992-93


3107		C


1995-96


2545		D


1998-99


2076		E


2001-02


1691		2B


2002-03


1002
F


2005-06


2165		G


2008-09


1818		H


2011-12


1522		3B


2012-13


1023		MB


2013-14


478		I


2015-16


2024		75 PLUS*
3x

2016-18


601		J


2018-19


1701		COVID-19
2x

2020-21


1128		K


2021-22


1393

Cohort 1

age 55-85

Cohort 2

age 55-65

Cohort 3

     age 55-65 

Migrant Cohort

         age 55-65

*Included only participants aged 75 years and over.


Data can be obtained from LASA upon request.

MB: Migrant 1st cohort, Baseline 2013-2014 (data processing finished, more information about this sample of people with a Moroccan or Turkish background will be provided in the near future).

For 75 PLUS and  COVID-19  see https://lasa-vu.nl/en/75-plus-study/ resp. https://lasa-vu.nl/en/covid-19-study/ for further reading.

Unique opportunities

The longitudinal nature of the study, together with its cross-sequential design and follow-up of almost three  decades provide several unique opportunities for data analysis. In addition to data on changes in functioning over time within respondents, provided by the long-term follow-up of the same participants, the addition of respondents from younger generations after ten and twenty years of follow-up allow for cohort and period comparisons.

Cohort papers

Further information about LASA, its data quality, data procedures and data collection can be found in the following cohort papers: