Why was the cohort set up?
In the early 1990s, few nationwide representative data on the health of the underage
population in Germany was identified. Thus, the Robert Koch Institute (RKI) conducted
the ‘German Health Interview and Examination Survey for Children and Adolescents’
(KiGGS) as the first nationwide health survey in this population, funded by the German
Federal Ministry of Health, Federal Ministry of Education and Research, and the RKI.
The survey comprised representative data on physical and mental health status, health
behaviours and other health determinants based on health examinations and interviews.
1
Participants in the KiGGS Baseline study, who all grew up around the turn of the millennium
in Germany, are tracked into adulthood, with regular follow-ups, within the KiGGS
cohort.
2
,
3
Data from two longitudinal in-depth module studies using sub-samples, the BELLA Study
for mental health
4
and Motoric Module focusing on motor fitness,
5
can be linked to the KiGGS cohort.
The main aims of the KiGGS cohort are to:
identify typical health and health behaviour trajectories over the life course
describe variation in trajectories across different populations
analyse long-term health developments as a function of risk and protective factors
observe transition periods and their implications on health development.
Who is in the cohort?
The Baseline study of the KiGGS cohort was conducted from 2003 to 2006 as the first
nationwide health survey among children and adolescents aged 0–17 years with primary
residence in Germany.
1
A two-stage sampling protocol was used. First, to proportionately consider the population
size according to degree of urbanization and geographic distribution in Germany, 167
communities were selected as primary sample units (PSUs), with a disproportionate
number of PSUs in Berlin and East and West Germany, to represent these regions separately.
Second, an equal number of addresses per birth cohort were randomly selected in each
PSU from local population registries. Children and adolescents with non-German citizenship
were oversampled by a factor 1.5, to account for expected higher non-response rates
6
in this population.
The gross sample included 28 299 minors,
6
who were invited to participate in the survey by postal letter sent to their parents
or custodians. To maximize participation, non-responding parents were contacted by
telephone. Additionally, personal visits were conducted if parents did not respond
initially or could not be reached via telephone. Moreover, incentives were used and
accompanying local public relations work was carried out prior to the field phase.
Migrant-specific activities were conducted to increase participation among children
with a migration background.
7
After excluding non-eligible cases, the gross sample was N = 26 787, including oversampling,
and N = 25 602 without including oversampling. In total, 17 641 respondents were included,
with a response rate (RR) 66.6%; this RR refers to the gross (N = 25 602) and net
(n = 17 056) sample without oversampling. Referring to the gross (N = 26 787) and
net (n = 17 641) sample, including oversampling of children and adolescents with non-German
citizenship, the RR was 65.9%. A total of 8985 boys (RR 66%) and 8656 girls (RR 67%)
took part in the survey. One study participant requested retrospective deletion of
all personal contact and survey data such that 17 640 respondents were finally included
in the cohort. There were no differences in the RR with respect to sex and age group.
A lower RR was reached among families with non-German citizenship (RR 51%) than among
those with German citizenship (RR 68%). Response was lower in major cities (>100 000
residents; RR 58%) than in smaller municipalities (RR 70%). A short questionnaire
on basic socio-demographic and health-related information was completed by two-thirds
of non-responders. Comparison of basic information between non-responders and responders
showed no differences in health indicators. Differences in mothers’ education level
suggested a slight middle-class bias.
1
,
6
To yield representative statements, a weighting factor was calculated to account for
the clustered sample design and deviations in the net sample from the population structure
with respect to age (years), sex, non-German citizenship, federal state (on 31 December
2004) and parents’ highest educational attainment (according to the German Census
of 2005).
6
Crude and weighted sample characteristics are shown in Table 1.
Table 1.
Examples of baseline socio-demographic and health characteristics of the KiGGS cohort
(recruited from 2003–2006)
a
Age, years
0–2 (N = 2805)
3–6 (N = 3875)
7–10 (N = 4148)
11–13 (N = 3076)
14–17 (N = 3736)
N
%
b
% wt**
N
%
b
% wt**
N
%
b
% wt**
N
%
b
% wt**
N
%
b
% wt**
Demographics (according to registration office)
Non-German citizenship
133
4.7
5.4
316
8.2
9.3
415
10.0
11.5
276
9.0
9.5
339
9.1
8.9
Region of residence: Western Germany (excluding Berlin)
1839
65.6
82.4
2571
66.4
83.9
2796
67.4
86.4
2065
67.1
86.5
2470
66.1
78.1
Municipality size: <5000
611
21.8
16.9
866
22.4
17.6
873
21.1
18.0
664
21.6
18.1
792
21.2
19.3
5000 to <20 000
755
26.9
24.8
1024
26.4
26.0
1108
26.7
27.2
817
26.6
27.6
951
25.5
27.3
20 000 to <100 000
800
28.5
29.8
1139
29.4
29.8
1218
29.4
29.6
890
28.9
28.9
1119
30.0
29.4
100 000 or more
639
22.8
28.4
846
21.8
26.7
949
22.9
25.2
705
22.9
25.4
874
23.4
24.0
Demographics (information given by parents)
Child’s sex: Female
1389
49.5
48.7
1924
49.7
48.7
2021
48.7
48.7
1488
48.4
48.7
1832
49.0
48.7
Migration background:
One-sided
280
10.1
11.6
317
8.3
9.7
309
7.5
8.2
188
6.1
7.2
198
5.3
6.1
Two-sided
361
13.0
17.6
569
14.8
19.3
606
14.7
18.1
487
15.8
17.9
567
15.2
15.6
Missing
18
32
26
0
4
Education of family
c
: Low
355
12.8
25.3
555
14.5
28.6
692
16.9
33.1
566
18.7
37.0
692
19.2
35.8
Middle
1616
58.3
49.4
2205
57.5
48.2
2281
55.6
46.0
1676
55.4
43.8
1940
53.9
44.5
High
803
29.0
25.2
1076
28.1
23.2
1131
27.6
20.9
785
25.9
19.2
969
26.9
19.7
Missing
31
39
44
49
135
Socio-economic status of family: Low
417
15.0
19.1
606
15.8
20.1
681
16.6
21.4
493
16.3
19.9
517
14.4
18.4
Middle
1656
59.7
57.9
2270
59.3
58.6
2444
59.6
59.1
1840
60.9
61.5
2191
61.2
62.5
High
699
25.2
23.0
955
24.9
21.3
976
23.8
19.5
688
22.8
18.7
873
24.4
19.1
Missing
33
44
47
55
155
Health status and behaviours
General health
8
: Very good/good
2698
97.0
97.1
3595
93.4
92.9
3888
94.4
93.9
2828
93.0
92.4
3296
91.0
90.4
Missing
22
25
31
35
114
Children with special health care needs: CSHCN
9
Screening positive
128
5.0
4.7
405
11.7
11.4
645
17.0
17.0
503
17.4
16.1
545
15.9
15.4
Missing
220
399
344
241
299
Allergic rhinitis (hay fever): Lifetime diagnosis yes
39
1.5
1.6
226
6.2
6.5
442
11.4
11.7
460
16.1
15.4
680
20.0
20.0
Missing (refused/‘don’t know’)
123
241
271
225
330
Bronchial asthma: Lifetime diagnosis yes
15
0.5
0.5
91
2.4
2.9
192
4.7
4.8
215
7.1
6.6
261
7.1
7.0
Missing (refused/‘don’t know’)
40
60
54
42
51
Atopic dermatitis: Lifetime diagnosis yes
286
10.8
10.2
616
17.0
16.4
735
18.8
17.4
519
18.1
17.4
568
16.6
16.5
Missing (refused/‘don’t know’)
165
250
245
201
312
Attention deficit hyperactive disorder: Lifetime diagnosis
yes
91
2.5
2.7
287
7.5
7.8
255
9.0
9.1
237
6.9
7.9
Missing (refused/‘don’t know’)
2805 not measured
275
319
240
305
SDQ-measured mental health problems:
10
Total score borderline or abnormal
691
18.2
19.4
854
21.0
22.5
627
20.8
21.5
557
15.5
16.7
Missing
2805 not measured
69
75
68
146
Current smoking: Yes
124
4.1
3.4
1170
31.7
33.2
Missing
2805 not measured
3875 not measured
4148 not measured
43
40
Obesity
d
: Yes
20
2.2
2.5
120
3.1
3.2
269
6.5
7.1
207
6.8
7.9
308
8.3
9.5
Missing
1890 (1860 children age <2 years excluded)
39
17
12
21
a
n = 17 640 because one study participant requested the retrospective deletion of all
of their contact and survey data.
b
Proportion in crude net sample (excluding missing values); wt** = weighted prevalence
rates (to German minor population 31 12 2004).
c
Education groups according to CASMIN (Comparative Analysis of Social Mobility in Industrial
Nations).
d
Based on national German reference percentiles.
11
How often have they been followed up?
Up to 2018, two follow-ups have been completed (Figure 1). The first follow-up (KiGGS
Wave 1) was carried out between 2009 and 2012 as a computer-assisted telephone interview
survey.
12
At that time, cohort participants were between 6 and 24 years old. The second follow-up
(KiGGS Wave 2) was conducted as a health examination and interview survey between
2014 and 2017, with study centres located in the same 167 PSUs as in the KiGGS Baseline
study.
13
If participants had moved to other communities or they did not want to or could not
come to a study centre, they were invited to take part solely in the health interview
part, which was conducted using a written questionnaire. To increase response among
the young adult (≥18 years) population, online health questionnaires were offered
to all young people who had not responded by the end of the health examination period.
Participants were 10–29 years old at the time of invitation and ≤31 years old at the
time of survey participation.
2
Figure 1.
Study design of the KiGGS cohort.
All Baseline study participants were invited to take part in these follow-ups if permission
to be contacted again had been given by their parents, or later, by the adult participants
themselves. Former respondents for whom permission to be re-contacted was not given,
and those who had died or lived permanently abroad, were excluded from invitation.
Current addresses were checked using local population registries. Postal invitations
and reminder letters were sent. Non-respondents were contacted by telephone and in
KiGGS Wave 2 home visits were conducted in the 167 PSUs.
In Wave 1, 11 992 (68%) of the 17 641 Baseline survey respondents participated again
(6078 female and 5914 male participants). In Wave 2, 10 853 (62%) cohort members took
part in the survey (5790 female and 5063 male participants). For 6465 of these participants
(3254 female and 3211 male), additional examination data are available (37% of the
Baseline sample).
2
For 8979 cohort members (51% of 17 641 Baseline participants), data are available
for all three periods of data collection; for 5554 of these participants (31% of the
Baseline sample), examination data in Wave 2 are available. A total 1874 participants
(11% of Baseline sample) did not take part in Wave 1 but could be included again in
Wave 2. A total 3013 persons (17% of the Baseline sample) took part in the Baseline
survey and Wave 1 but not Wave 2. A total 3775 Baseline participants (21%) did not
take part in either of the two subsequent waves.
2
The reasons for non-participation in the two follow-ups are given in Table 2. Only
a few participants refused to be contacted again, so a high degree of commitment to
the study can be assumed. In total, 33 participants are deceased; it would be necessary
to conduct a mortality follow-up to obtain information about the causes of death.
Table 2.
Final disposition codes and loss to follow-up in KiGGS Waves 1 and 2
Wave 1
Wave 2
Temporary codes
Non-participation: refusal
2036
2753
Non-participation: no contact
a
2914
3562
Non-participation: minimum requirements not met
b
497
85
Respondents
11 992
10 853
Sub-total
17 439
17 253
Constant loss (cumulative)
Retrospective deletion of all contact and survey data, requested by respondent
1
1
Deceased
16
33
Non-participation: permanently living abroad
99
205
Non-participation: unknown address
c
7
8
Non-participation: cohort consent withdrawn
79
141
Sub-total
202
388
Total
17 641
17 641
a
In this article, ‘contact’ is defined as having an interaction with the specific target
person. During participant recruitment, it was common to have contact with other (family)
members of the target persons’ household. These cases were assigned to the ‘no contact’
category. Therefore, the number of contacts may be underestimated.
b
Insufficient amount of data and/or missing informed consent.
c
Research at official residency registries prior to invitation returned status of non-traceable
address.
The loss to follow-up in the KiGGS cohort is strongly associated with socio-demographic
characteristics. A lower probability of re-participation is associated with older
age, male sex, lower socio-economic status (SES) and a migration background (see Table 3).
Table 3.
Loss-to-follow-up in the KiGGS cohort by socio-demographic characteristics; all numbers
and percentages are unweighted
t0: KiGGS Baseline 2003–2006
t1: KiGGS Wave 1 2009–2012
t2: KiGGS Wave 2 2014–2017
n
n
%
n
%
n
%
Health examination and interview
Health Interview (Telephone)
Health interview
Subgroup with additional examination
Age at t0
0–2 years
2805
1929
68.8
1923
68.6
1472
52.5
3–6 years
3875
2881
74.3
2699
69.7
2082
53.7
7–10 years
4148
3021
72.8
2527
60.9
1458
35.1
11–13 years
3076
1986
64.6
1697
55.2
747
24.3
14–17 years
3736
2175
58.2
2007
53.7
706
18.9
Sex
Male
8986
5913
65.8
5061
56.3
3211
35.7
Female
8654
6079
70.2
5792
66.9
3254
37.6
Socio-economic status of the family at t0
Low
2714
1199
44.2
1179
43.4
711
26.2
Middle
10 401
7292
70.1
6575
63.2
3969
38.2
High
4191
3396
81.0
2980
71.1
1727
41.2
Missing
334
105
31.4
119
35.6
58
17.4
Migration background
No
13 678
9941
72.7
8926
65.3
5277
38.6
One-sided
1292
799
61.8
738
57.1
432
33.4
Two-sided
2590
1214
46.9
1143
44.1
724
28.0
Missing
80
38
47.5
46
57.5
32
40.0
Total
17 640
a
11 992
68.0
10 853
61.5
6465
36.6
a
n = 17 640 because one study participant requested the retrospective deletion of all
of their contact and survey data.
Longitudinal weighting factors have been calculated for both follow-ups, to compensate
for possible attrition bias owing to differential dropout. Weighting factors were
calculated as the cross-sectional weight of the KiGGS Baseline (adjusted to the population
as of 31 December 2004) multiplied by a dropout weight. The dropout weight is given
by the inverse probability of participation in the follow-up wave. This probability
was modelled using a weighted logistic regression model that includes socio-demographic
and health behaviour-related indicators as predictors. This weighting results in higher
weights for groups that tend to be less willing to participate in the follow-up.
What has been measured?
The KiGGS cohort is characterized by a thematic breadth of collected data, ranging
from physical and mental health to health behaviour, psycho-social factors, social
background and use of health care services. The survey contents are dependent on the
survey modes used in the Baseline survey and the two follow-up waves (Figure 2).
Figure 2.
Data collection methods and topics used in the KiGGS cohort across three data collection
waves.
Health examination
An age-specific health examination was conducted in the KiGGS Baseline study and KiGGS
Wave 2. Measurement of body weight, height and waist circumference
14
in both waves was supplemented with analysis of body composition by means of bioimpedance
measurement in Wave 2, to observe the development of obesity over the life course.
Further anthropometric measurements included head circumference and skinfolds at baseline.
As important indicators of cardiovascular health, the resting blood pressure and heart
rate were measured in both waves.
15
In addition, to identify preclinical arteriosclerosis, sonographic evaluation of the
intima-media thickness of the carotid artery wall was implemented in Wave 2. Thyroid
size and structure were also examined by ultrasound at baseline. An eye examination
was performed, and motor restlessness and skin condition were additionally assessed.
Physical fitness was tested in both waves for children aged 4–10 years using a motor
ability test battery to test strength, flexibility, coordination;
16
in adolescents and young adults aged 11–29 years, a cycle ergometry test was used
to assess cardiorespiratory fitness. Measurement of total physical activity using
accelerometry over 7 days was added in Wave 2.
Participants were asked for a blood sample and spot urine sample.
17
Electrolytes, transaminases, retention values, blood lipids, thyroid hormone levels,
micronutrients, sensitization to common allergens and immune status for selected infections
were determined using standardized laboratory methods (see Supplementary data, available
at IJE online). To document vaccination status, participants were asked to provide
their vaccination records.
Participants’ use of drugs within the last 7 days (prescription and over-the-counter)
was registered using a computer-assisted personal interview.
18
Data on physician-diagnosed diseases and chronic conditions (allergic diseases such
as hay fever, neurodermatitis and asthma; migraine; epilepsy; and heart diseases)
were collected in a second computer-assisted personal interview by the study physician
in both examination waves. Participants who only took part in the health interview
in Wave 2 answered these questions using a self-administered written or online questionnaire.
13
Health interview
A broad range of health information was collected using self-administered questionnaires
in the Baseline study and Wave 2, whereas a telephone interview was conducted in Wave
1. Age group-specific questionnaires were used. In all waves, questionnaires were
administered to parents of participants aged 0–17 years and directly to participants
aged 11–17 years. Starting from Wave 1, all information of participants aged ≥18 years
was collected exclusively via self-report questionnaires.
As a short assessment of participants’ health status, questions from the Minimum European
Health Module
8
were included, supplemented with the screening instrument to identify children with
special health care needs (CSHCN screener)
9
in the Baseline study; other health indicators for physical health were pregnancy
conditions, birth weight, premature birth, childhood infectious diseases, pain, accidents,
development and maturity, and reproductive health.
Health-related quality of life was measured using the KINDL-R questionnaire
19
in the Baseline study for participants aged 3–17 years; in later surveys, this was
followed by the KIDSCREEN
20
for participants in the same age range and the SF-8
21
,
22
for young adults. The Strengths and Difficulties Questionnaire (SDQ)
10
was administered to screen mental health problems (for ages 3–17 years) in every wave,
complemented by the extended version starting from Wave 1, to include associated impairments.
23
Other mental health screening instruments were the SCOFF
24
for eating disorders (ages 11–31 years) and subscales of the Patient Health Questionnaire
for panic and depressive disorders (ages 18–31 years).
25
Preclinical mental health symptoms of young adults were operationalized using two
subscales of the 36-Item Short Form Survey SF-36, the Mental Health Inventory MHI-5
and Energy/Vitality.
26
At each point in the interviewing process, physician- or psychologist-diagnosed mental
disorders were queried.
Personal protective factors were self-reported in all waves using the WIRKALL scale
of self-efficacy
27
and a short scale of personal resources.
28
Social support was measured with the Social Support Scale.
29
Personality was operationalized in Wave 2 using a short version of the Big Five Inventory
(BFI-10)
30
and well-being in young adults with the Personal Wellbeing Index for Adults (PWI-A).
31
Self-reported experiences of violence were recorded in the Baseline study and Wave
1. Retrospective queries about childhood trauma (using the Childhood Trauma Questionnaire),
32
other adverse childhood experiences (using the Adverse Childhood Experiences International
Questionnaire
33
), experiences of discrimination, major health events, critical life events such as
parents’ separation or death, moving out of the parents’ home, and participants’ own
partnership and educational history were included in questionnaires administered to
young adults in Wave 2.
Questions on several health behaviours like tobacco use, total physical activity and
sporting activities, or use of screen-based media were queried in each survey. Alcohol
consumption was operationalized using the Alcohol Use Disorders Identification Test
(Audit-C).
34
,
35
In Wave 2, the European Health Interview Survey-Physical Activity Questionnaire
36–38
was implemented among young adults. To measure food intake, a food frequency questionnaire
39
was administered in the Baseline study and Wave 2.
Medical care utilization within the last 12 months was queried in all age groups and
at all measurement times; this included several medical professions and institutions
as well as health insurance. As a special focus in KiGGS Wave 2, information on treatment
for diagnosed obesity, bronchial asthma and mental disorders over the lifespan was
retrospectively collected.
The KiGGS cohort collects comprehensive information on family and social determinants
of health. Questions on household composition, parental marital status and biological
siblings were queried in each survey wave; starting from Wave 2, retrospective and
current information on blended families can be provided. Familial predisposition to
major diseases was assessed by asking about previous diagnoses in participants’ biological
parents. Family climate was assessed using a modified version of the Family Climate
Scale,
40
parenting style with the D-ZKE (The Zurich Short Questionnaire on Parenting Behaviour),
41
well-being of parents using the PWI-A
31
and parental personality with the BFI-10.
30
Duration of out-of-family care during childhood is known for all respondents. Characteristics
of the home environment and neighbourhood as well as environmental contamination and
noise annoyance were included, especially in Wave 2.
Migration background was operationalized using a multidimensional view. Information
collected included nationality, country of birth, year of parents’ immigration and
languages spoken at home.
7
,
42
Standardized questions on education, income and employment status of the parents and
young adults themselves (ages 18–31 years) were queried.
43
,
44
For young adults, information about educational trajectories and employment over their
lifespan was also collected. For participants <18 years old, data on education patterns
such as school type, grade, history and performance were collected. As a subjective
indicator, subjective social status
45
,
46
was implemented in Wave 2.
A detailed overview of all topics collected in the KiGGS cohort study is given in
Supplementary data, available at IJE online.
What has it found? Key findings and publications
The Baseline study of the KiGGS cohort was a population-based cross-sectional health
examination and health interview survey that provided nationally representative information
on the health of children and adolescents aged 0–17 years living in Germany after
the turn of the millennium. KiGGS Baseline study results identified crucial public
health-related topics. Overweight and obesity were determined to be an increasing
problem. Compared with the results of studies conducted in the 1980s and 1990s, the
prevalence of overweight children increased by 50%, and the proportion of obese children
and adolescents more than doubled.
47
Non-communicable diseases, such as allergies and bronchial asthma,
48
emotional and conduct problems,
49
and diagnosed attention deficit hyperactivity disorder
50
have become more prominent in recent decades. A strong relationship between SES and
children’s health was identified for many health indicators,
51
,
52
with lower self-rated health and health-related quality of life and more mental health
problems or hazardous health behaviours
53
,
54
among those living in socially disadvantaged families.
To date, two follow-ups of participants in the baseline survey have been carried out
within the framework of the KiGGS cohort. After finalizing the data processing for
KiGGS Wave 2, trajectories of the main topics of physical and mental health, health
behaviours, and their causes and influences can be analysed over the life course.
Currently, the first results have been published.
Analysis of laboratory parameters obtained in the Baseline study and Wave 2 showed
clear positive transition probabilities among both sexes for allergic sensitization
against the allergen mixture SX1, which includes eight common inhalant allergens (defined
as specific IgE antibodies with a value of ≥0.35 kU/l) as a main risk factor in the
development of allergies, such as hay fever or asthma.
55
For the same follow-up period, analysis of preschool children aged 2–6 years at baseline
identified a high persistence of obesity in >60% of obese children into their adolescence;
overweight showed a higher convertibility.
56
Mental health problems in childhood showed high variability as well. These were assessed
using the parental version of the SDQ, which classifies respondents with a total SDQ
score above the cut-off of the German norm sample as children and adolescents with
mental health problems. Only 50% of children and adolescents with mental health problems
in the KiGGS Baseline study still displayed symptoms 6 years later in Wave 1.
57
Focusing on the development of health or health behaviours during transition periods,
we found that adolescence is the critical phase for smoking status in young adulthood;
85% of adolescent smokers continued smoking into young adulthood and approximately
nine of ten adult smokers began smoking in adolescence.
58
Female sex, lower parental education level and income, and lower motor fitness at
baseline were identified as the main predictors of a permanent lack of or intermittent
participation in organized sports during the transition from childhood to adolescence.
38
Looking at the importance of social and familial environments for health development
revealed the importance of one's own education and intergenerational educational mobility
for the existence and persistence of health inequalities among young people. Poor
self-rated health is less likely to be reported if intergenerational education levels
are constantly high or upwardly mobile.
59
Another analysis focusing on family structure showed poorer health and higher rates
of smoking among adolescents in non-nuclear families, especially those whose parents
separated after the Baseline survey.
60
What are the main strengths and weaknesses?
The KiGGS cohort study is the only population-based cohort study in Germany to date
in which a broad spectrum of health parameters is surveyed, beginning in early childhood
and continuing through adolescence and well into adulthood. The sample is large and
representative of minors living in Germany at the time of the KiGGS Baseline study.
A wide range of topics enable comprehensive analyses of health trajectories and their
determinants over the life course. Health interviews are supplemented with objective
measurement data obtained by health examinations as well as blood and urine sample
collection. Within the next 10 years, all ‘children’ in the KiGGS cohort will have
become adults aged from 18 to >40 years. This will permit us to conduct comprehensive
analyses of the effects of living conditions of children and adolescents at the turn
of the millennium on their health status in adulthood.
A limitation of the study is the long period (5–6 years) between data collection waves.
As the survey method changed from written questionnaires to telephone interviews between
the Baseline study and Wave 1, possible mode effects must be carefully considered
for the indicators analysed. Another restraint is owing to changes in the instruments
used, particularly between adolescence and young adulthood. A further limitation is
the relatively high dropout rate during the health examination portion of KiGGS Wave
2, owing to the high mobility of young adults combined with restriction of the examinations
to those communities originally sampled at baseline. Additionally, reaching majority
age has an impact on participation motivation, as parents are no longer part of the
decision-making process. In line with other cohort studies, there is a lower willingness
to re-participate among young men and those with lower SES or a migrant background.
Using the longitudinal weighting factor is assumed to diminish possible effects of
selective study participation for variables included in the weighting procedure. However,
this can only control for variables collected at the time of KiGGS baseline, not at
the time of the follow-ups.
Can I get hold of the data? Where can I find out more?
The dataset of the KiGGS Baseline study is available to interested researchers on
application as de facto anonymized data for scientific secondary analysis. The use
of longitudinal data of further waves is permitted upon receipt of a informal request
and description of the planned project to the ‘Health Monitoring’ Research Data Centre,
Robert Koch Institute, Berlin, Germany (e-mail: datennutzung@rki.de). Further information
and additional study results can be found here: http://www.kiggs-studie.de/english/results.html
Profile in a nutshell
The KiGGS cohort was established in addition to periodically conducted nationwide
representative health surveys of children and adolescents aged 0–17 years (KiGGS cross-section)
to complement regularly reported trends in prevalence rates among children and adolescents
with health development analysis over the life course.
The first population-based nationwide sample of children and adolescents in Germany
(KiGGS Baseline study; ages 0–17 years; n = 8656 girls and 8985 boys) was tracked
for the first time using telephone health interviews (KiGGS Wave 1: 2009–2012; n = 6079
female and 5913 male participants; re-participation rate 68%). A total of 10 853 participants
of the Baseline study (5790 female, 5063 male) completed questionnaires in the health
interview of the second follow-up (KiGGS Wave 2: 2014–2017). Additional examination
data are available for 6465 of these re-participants (3254 female, 3211 male).
Data were collected using questionnaires, physician-administered personal interviews,
health examinations and testing, and laboratory analysis. Topics of the KiGGS cohort
include numerous physical and mental health indicators, health behaviours, and health
care utilization and personal, familial, environmental and socio-economic health determinants.
Cohort data are available via request with a description of planned projects at Research
Data Centre, Robert Koch Institute, Berlin, Germany (e-mail: datennutzung@rki.de).
Funding
The Baseline study of the KiGGS cohort was funded by the German Federal Ministry of
Health, the Ministry of Education and Research, and the RKI. After establishing the
German Health Monitoring System in 2008, further waves of the KiGGS study were funded
by the German Federal Ministry of Health and the RKI only.
Ethics
All studies of the RKI are subject to strict compliance with the data protection regulations
of the EU Basic Data Protection Regulation (DSGVO) and Federal Data Protection Act
(BDSG). The Ethics Commission of the Charité Universitätsmedizin Berlin has reviewed
the KiGGS basic survey (No. 101/2000) as well as KiGGS wave 1 (No. EA2/058/09); and
the Ethics Commission of the Medizinische Hochschule Hannover has reviewed ethical
aspects and approved KiGGS wave 2 (No. 2275-2014). Participation in the studies was
voluntary. Participants or their guardians were informed about the aims and contents
of the studies as well as about data protection and gave their written consent.
Supplementary Material
dyz231_Supplementary_Data
Click here for additional data file.