Children with a chronic disease face more obstacles than their healthy peers, which may impact their physical, social-emotional, and cognitive development. In the long run, children with a chronic disease reach developmental milestones later than their healthy peers and many children will remain dependent on medication and/ or will be limited in their daily life activities. The PROactive Cohort Study aims to assess fatigue, participation, and psychosocial well-being across children with various chronic diseases over the course of their lifespan since their increased vulnerability is a fact. These factors have the potential to influence their identity and how they grow into autonomous adults that take part in our society. Also the PROactive Cohort Study is aimed at supporting people with chronic and/or life-threatening conditions to increase their ability to adapt, and their self-manage capacities. This means that PROactive also systematically monitors the child's capacity and ability to play and the well-being of the patients and their families. This knowledge can be used as an innovative and interactive method for creating prevention and treatment strategies. This will help to assess vulnerabilities and resilience among children with chronic and/or life-threatening conditions and their families. This cohort study follows a continuous longitudinal design. It is based at the Wilhelmina Children's Hospital in the Netherlands and has been running since December 2016. Children with a chronic disease (e.g. cystic fibrosis, juvenile idiopathic arthritis, chronic kidney disease, or congenital heart disease) in a broad age range (2-18 years) are included, as well as their parent(s). Patient-reported outcome measures (PROMs) are collected from parents (children between 2-18 years) and children (8-18 years). The PROactive Cohort Study uses a flexible design in which the research assessment is an integrated part of clinical care. Children are included when they visit the outpatient clinic and are followed up annually, preferably linked to another outpatient visit.

The Centre for Longitudinal Studies (CLS) and the MRC Unit for Lifelong Health and Ageing (LHA) have carried out two online surveys of the participants of five national longitudinal cohort studies which have collected insights into the lives of study participants including their physical and mental health and wellbeing, family and relationships, education, work, and finances during the coronavirus pandemic. The Wave 1 Survey was carried out at the height of lockdown restrictions in May 2020 and focussed mainly on how participants’ lives had changed from just before the outbreak of the pandemic in March 2020 until then. The Wave 2 survey was conducted in September/October 2020 and focussed on the period between the easing of restrictions in June through the summer into the autumn. A third wave of the survey was conducted in early 2021.

In addition, CLS study members who had participated in any of the three COVID-19 Surveys were invited to provide a finger-prick blood sample to be analysed for COVID-19 antibodies. Those who agreed were sent a blood sample collection kit and were asked to post back the sample to a laboratory for analysis. The antibody test results and initial short survey responses are included in a single dataset, the COVID-19 Antibody Testing in the National Child Development Study, 1970 British Cohort Study, Next Steps and Millennium Cohort Study, 2021 (SN 8823).

The CLS studies are:

• Millennium Cohort Study (born 2000-02) both cohort members and parents (MCS)
• Next Steps (born 1989-90) (NS)
• 1970 British Cohort Study (BCS70)
• 1958 National Child Development Study (NCDS).

The LHA study is:

• MRC National Survey of Health and Development, 1946 British birth cohort (NSHD)

The content of the MCS, NS, BCS70 and NCDS COVID-19 studies, including questions, topics and variables can be explored via the CLOSER Discovery website.

The COVID-19 Survey in Five National Longitudinal Cohort Studies: Millennium Cohort Study, Next Steps, 1970 British Cohort Study and 1958 National Child Development Study, 2020-2021 contains the data from waves 1, 2 and 3 for the 4 cohort studies. The data from all four CLS cohorts are included in the same dataset, one for each wave.

The COVID-19 Survey data for the 1946 birth cohort study (NSHD) run by the LHA is held under "https://beta.ukdataservice.ac.uk/datacatalogue/studies/study?id=8732" style="background-color: rgb(255, 255, 255);">SN 8732 and available under Special Licence access conditions.

Latest edition information
For the fourth edition (June 2022), the following minor corrections have been made to the wave 3 data:

• corrections to a small number of cases where CW3_GROW and CW3_GROWB were incorrectly calculated
• recoded values and reformatted the code list for CW3_COVIDVAC as the original value of 3 was removed from the final version of the survey
  

Chad TD: Persistence to Grade 5: % of Cohort data was reported at 78.596 % in 2017. This records an increase from the previous number of 28.862 % for 2016. Chad TD: Persistence to Grade 5: % of Cohort data is updated yearly, averaging 48.301 % from Dec 1976 (Median) to 2017, with 20 observations. The data reached an all-time high of 78.596 % in 2017 and a record low of 28.862 % in 2016. Chad TD: Persistence to Grade 5: % of Cohort data remains active status in CEIC and is reported by World Bank. The data is categorized under Global Database’s Chad – Table TD.World Bank.WDI: Social: Education Statistics. Persistence to grade 5 (percentage of cohort reaching grade 5) is the share of children enrolled in the first grade of primary school who eventually reach grade 5. The estimate is based on the reconstructed cohort method.;UNESCO Institute for Statistics (UIS). UIS.Stat Bulk Data Download Service. Accessed April 5, 2025. https://apiportal.uis.unesco.org/bdds.;Weighted average;

Trinidad and Tobago TT: Persistence to Grade 5: Male: % of Cohort data was reported at 90.340 % in 2009. This records a decrease from the previous number of 96.989 % for 2008. Trinidad and Tobago TT: Persistence to Grade 5: Male: % of Cohort data is updated yearly, averaging 92.283 % from Dec 2004 (Median) to 2009, with 4 observations. The data reached an all-time high of 96.989 % in 2008 and a record low of 88.784 % in 2004. Trinidad and Tobago TT: Persistence to Grade 5: Male: % of Cohort data remains active status in CEIC and is reported by World Bank. The data is categorized under Global Database’s Trinidad and Tobago – Table TT.World Bank: Education Statistics. Persistence to grade 5 (percentage of cohort reaching grade 5) is the share of children enrolled in the first grade of primary school who eventually reach grade 5. The estimate is based on the reconstructed cohort method.; ; United Nations Educational, Scientific, and Cultural Organization (UNESCO) Institute for Statistics.; Weighted average;

Synthetic dataset for NC births in 2000. The individual level data contains 26 key variables, including synthetically derived information on births, blood lead level test results, end-of-year grade 4 test results, air quality at select time points, and social / economic factors.

The case-cohort study design combines the advantages of a cohort study with the efficiency of a nested case-control study. However, unlike more standard observational study designs, there are currently no guidelines for reporting results from case-cohort studies. Our aim was to review recent practice in reporting these studies, and develop recommendations for the future. By searching papers published in 24 major medical and epidemiological journals between January 2010 and March 2013 using PubMed, Scopus and Web of Knowledge, we identified 32 papers reporting case-cohort studies. The median subcohort sampling fraction was 4.1% (interquartile range 3.7% to 9.1%). The papers varied in their approaches to describing the numbers of individuals in the original cohort and the subcohort, presenting descriptive data, and in the level of detail provided about the statistical methods used, so it was not always possible to be sure that appropriate analyses had been conducted. Based on the findings of our review, we make recommendations about reporting of the study design, subcohort definition, numbers of participants, descriptive information and statistical methods, which could be used alongside existing STROBE guidelines for reporting observational studies.

These data are calculated based on the cohort year, i.e. the academic year in which a group of students began university studies. In each COHORTE COURSE, all data (including those corresponding to graduation) are referenced to the year in which studies were initiated in order to track students who started studies at the same time. Graduate students collect the number of students from a new-entry cohort who have completed all curriculum credits, regardless of the year they ended. Students Graduate in Time is the number of students from a new income cohort who graduate in the expected time or another year. Abandonment Rate is the percentage of students from a new income cohort who must have obtained the degree in the expected academic year, according to the duration of the plan, and who have not enrolled in either that academic year or the following year. Initial Abandonment Rate is the percentage of students from a new income cohort who, without obtaining the degree, do not enroll in the study either of the two academic years following the entry Rate of Graduation Percentage of students who complete teaching in the expected time or in one more year in relation to their entry cohort. The fees exclude students in grade adaptation courses, students who have recognised (or adapted or validated) more than 15 % of the credits in the curriculum and students who have received the part-time modality in any of the years completed. Cohort data by degree with measurement rates, students presented, evaluated and exceeded.

Connecticut's Birth to Three System (B23) supports families with infants and toddlers that have developmental delays to learn new ways to make everyday activities enhance the child's development. Birth to Three is administered pursuant to Part C of the Individuals with Disabilities Education Act (IDEA). Once families with children below age 3 are referred, the child's development is evaluated for eligibility, and if eligible the family can receive supports until the child no longer has delays or until the child turns age 3. Because an infant can be referred within days of being born, a family may be enrolled for almost three full years. Connecticut's Birth to Three System publishes data annually by the fiscal and calendar year and longitudinally by birth cohort. CTData.org carries both sets of data, here and in 'Birth To Three Annual Data'. Birth cohort data looks at all children born in a particular year and tracks whether the family received B23 support. For example, the latest full year available in this dataset is for those children born in 2013 since they turned age 3 sometime in 2016. The 2013 data will tell you how many children there were whose families received support at some point during the first three years of the child's life. CTData calculates several indicators using total number of births in a town. This provides users with a general idea of the relative number of children in the community eligible for services. Using births is not perfect since families move in and out of town so it should not be used as an exact figure but as a general reference point. Below are how the indicators are calculated: % Referrals = Number referred divided by total number of births % Evaluations = Number evaluated divided by total number of births % Eligible = Number eligible divided by total number of births % Individual Family Service Plans (IFSP) = Number with IFSP divided by total number of births % Served = Number served divided by total number of births % Exited to Early Childhood Special Education = Number exited to early childhood special education divided by total number of births 'Referred that are Evaluated' represents the percent of children that were evaluated out of the total number of children referred to the Birth to Three System. 'Evaluated that are Eligible' represents the percent of children who were deemed eligible out of the total number of children that were evaluated. 'Eligible that Recieve IFSP' represents the percent of children whose family recieved an Individual Family Service Plan out of the total number of eligible children.

Chad TD: Persistence to Last Grade of Primary: Male: % of Cohort data was reported at 71.519 % in 2017. This records an increase from the previous number of 23.196 % for 2016. Chad TD: Persistence to Last Grade of Primary: Male: % of Cohort data is updated yearly, averaging 43.237 % from Dec 1976 (Median) to 2017, with 20 observations. The data reached an all-time high of 71.519 % in 2017 and a record low of 23.196 % in 2016. Chad TD: Persistence to Last Grade of Primary: Male: % of Cohort data remains active status in CEIC and is reported by World Bank. The data is categorized under Global Database’s Chad – Table TD.World Bank.WDI: Social: Education Statistics. Persistence to last grade of primary is the percentage of children enrolled in the first grade of primary school who eventually reach the last grade of primary education. The estimate is based on the reconstructed cohort method.;UNESCO Institute for Statistics (UIS). UIS.Stat Bulk Data Download Service. Accessed April 5, 2025. https://apiportal.uis.unesco.org/bdds.;Weighted average;

Since the beginning of the 1960s, Statistics Sweden, in collaboration with various research institutions, has carried out follow-up surveys in the school system. These surveys have taken place within the framework of the IS project (Individual Statistics Project) at the University of Gothenburg and the UGU project (Evaluation through follow-up of students) at the University of Teacher Education in Stockholm, which since 1990 have been merged into a research project called 'Evaluation through Follow-up'. The follow-up surveys are part of the central evaluation of the school and are based on large nationally representative samples from different cohorts of students.

Evaluation through follow-up (UGU) is one of the country's largest research databases in the field of education. UGU is part of the central evaluation of the school and is based on large nationally representative samples from different cohorts of students. The longitudinal database contains information on nationally representative samples of school pupils from ten cohorts, born between 1948 and 2004. The sampling process was based on the student's birthday for the first two and on the school class for the other cohorts.

For each cohort, data of mainly two types are collected. School administrative data is collected annually by Statistics Sweden during the time that pupils are in the general school system (primary and secondary school), for most cohorts starting in compulsory school year 3. This information is provided by the school offices and, among other things, includes characteristics of school, class, special support, study choices and grades. Information obtained has varied somewhat, e.g. due to changes in curricula. A more detailed description of this data collection can be found in reports published by Statistics Sweden and linked to datasets for each cohort.

Survey data from the pupils is collected for the first time in compulsory school year 6 (for most cohorts). Questionnaire in survey in year 6 includes questions related to self-perception and interest in learning, attitudes to school, hobbies, school motivation and future plans. For some cohorts, questionnaire data are also collected in year 3 and year 9 in compulsory school and in upper secondary school.

Furthermore, results from various intelligence tests and standartized knowledge tests are included in the data collection year 6. The intelligence tests have been identical for all cohorts (except cohort born in 1987 from which questionnaire data were first collected in year 9). The intelligence test consists of a verbal, a spatial and an inductive test, each containing 40 tasks and specially designed for the UGU project. The verbal test is a vocabulary test of the opposite type. The spatial test is a so-called ‘sheet metal folding test’ and the inductive test are made up of series of numbers. The reliability of the test, intercorrelations and connection with school grades are reported by Svensson (1971).

For the first three cohorts (1948, 1953 and 1967), the standartized knowledge tests in year 6 consist of the standard tests in Swedish, mathematics and English that up to and including the beginning of the 1980s were offered to all pupils in compulsory school year 6. For the cohort 1972, specially prepared tests in reading and mathematics were used. The test in reading consists of 27 tasks and aimed to identify students with reading difficulties. The mathematics test, which was also offered for the fifth cohort, (1977) includes 19 assignments. After a changed version of the test, caused by the previously used test being judged to be somewhat too simple, has been used for the cohort born in 1982. Results on the mathematics test are not available for the 1987 cohort. The mathematics test was not offered to the students in the cohort in 1992, as the test did not seem to fully correspond with current curriculum intentions in mathematics. For further information, see the description of the dataset for each cohort.

For several of the samples, questionnaires were also collected from the students 'parents and teachers in year 6. The teacher questionnaire contains questions about the teacher, class size and composition, the teacher's assessments of the class' knowledge level, etc., school resources, working methods and parental involvement and questions about the existence of evaluations. The questionnaire for the guardians includes questions about the child's upbringing conditions, ambitions and wishes regarding the child's education, views on the school's objectives and the parents' own educational and professional situation.

The students are followed up even after they have left primary school. Among other things, data collection is done during the time they are in high school. Then school administrative data such as e.g. choice of upper secondary school line / program and grades after completing studies. For some of the cohorts, in addition to school administrative data, questionnaire data were also collected from the students.

Marshall Islands MH: Persistence to Grade 5: Female: % of Cohort data was reported at 81.838 % in 2008. This records an increase from the previous number of 74.356 % for 2006. Marshall Islands MH: Persistence to Grade 5: Female: % of Cohort data is updated yearly, averaging 78.097 % from Dec 2006 (Median) to 2008, with 2 observations. The data reached an all-time high of 81.838 % in 2008 and a record low of 74.356 % in 2006. Marshall Islands MH: Persistence to Grade 5: Female: % of Cohort data remains active status in CEIC and is reported by World Bank. The data is categorized under Global Database’s Marshall Islands – Table MH.World Bank: Education Statistics. Persistence to grade 5 (percentage of cohort reaching grade 5) is the share of children enrolled in the first grade of primary school who eventually reach grade 5. The estimate is based on the reconstructed cohort method.; ; United Nations Educational, Scientific, and Cultural Organization (UNESCO) Institute for Statistics.; Weighted average;

Laos LA: Persistence to Last Grade of Primary: Female: % of Cohort data was reported at 80.694 % in 2015. This records an increase from the previous number of 80.367 % for 2014. Laos LA: Persistence to Last Grade of Primary: Female: % of Cohort data is updated yearly, averaging 63.199 % from Dec 1992 (Median) to 2015, with 22 observations. The data reached an all-time high of 80.694 % in 2015 and a record low of 50.210 % in 1992. Laos LA: Persistence to Last Grade of Primary: Female: % of Cohort data remains active status in CEIC and is reported by World Bank. The data is categorized under Global Database’s Laos – Table LA.World Bank.WDI: Education Statistics. Persistence to last grade of primary is the percentage of children enrolled in the first grade of primary school who eventually reach the last grade of primary education. The estimate is based on the reconstructed cohort method.; ; UNESCO Institute for Statistics; Weighted average; Each economy is classified based on the classification of World Bank Group's fiscal year 2018 (July 1, 2017-June 30, 2018).

San Marino Persistence to Grade 5: Female: % of Cohort data was reported at 98.065 % in 2011. San Marino Persistence to Grade 5: Female: % of Cohort data is updated yearly, averaging 98.065 % from Dec 2011 (Median) to 2011, with 1 observations. San Marino Persistence to Grade 5: Female: % of Cohort data remains active status in CEIC and is reported by World Bank. The data is categorized under Global Database’s San Marino – Table SM.World Bank: Education Statistics. Persistence to grade 5 (percentage of cohort reaching grade 5) is the share of children enrolled in the first grade of primary school who eventually reach grade 5. The estimate is based on the reconstructed cohort method.; ; United Nations Educational, Scientific, and Cultural Organization (UNESCO) Institute for Statistics.; Weighted average;

Belgium BE: Persistence to Grade 5: Female: % of Cohort data was reported at 97.861 % in 2021. This records an increase from the previous number of 97.815 % for 2020. Belgium BE: Persistence to Grade 5: Female: % of Cohort data is updated yearly, averaging 92.021 % from Dec 1974 (Median) to 2021, with 29 observations. The data reached an all-time high of 100.000 % in 2012 and a record low of 72.441 % in 1977. Belgium BE: Persistence to Grade 5: Female: % of Cohort data remains active status in CEIC and is reported by World Bank. The data is categorized under Global Database’s Belgium – Table BE.World Bank.WDI: Social: Education Statistics. Persistence to grade 5 (percentage of cohort reaching grade 5) is the share of children enrolled in the first grade of primary school who eventually reach grade 5. The estimate is based on the reconstructed cohort method.;UNESCO Institute for Statistics (UIS). UIS.Stat Bulk Data Download Service. Accessed April 5, 2025. https://apiportal.uis.unesco.org/bdds.;Weighted average;

Saint Lucia LC: Persistence to Grade 5: Female: % of Cohort data was reported at 91.068 % in 2013. This records a decrease from the previous number of 95.038 % for 2012. Saint Lucia LC: Persistence to Grade 5: Female: % of Cohort data is updated yearly, averaging 94.675 % from Dec 1983 (Median) to 2013, with 11 observations. The data reached an all-time high of 98.037 % in 2007 and a record low of 89.522 % in 2011. Saint Lucia LC: Persistence to Grade 5: Female: % of Cohort data remains active status in CEIC and is reported by World Bank. The data is categorized under Global Database’s St. Lucia – Table LC.World Bank: Education Statistics. Persistence to grade 5 (percentage of cohort reaching grade 5) is the share of children enrolled in the first grade of primary school who eventually reach grade 5. The estimate is based on the reconstructed cohort method.; ; United Nations Educational, Scientific, and Cultural Organization (UNESCO) Institute for Statistics.; Weighted average;

Trinidad and Tobago TT: Persistence to Last Grade of Primary: Male: % of Cohort data was reported at 86.936 % in 2009. This records a decrease from the previous number of 93.346 % for 2008. Trinidad and Tobago TT: Persistence to Last Grade of Primary: Male: % of Cohort data is updated yearly, averaging 88.406 % from Dec 2004 (Median) to 2009, with 4 observations. The data reached an all-time high of 93.346 % in 2008 and a record low of 79.311 % in 2004. Trinidad and Tobago TT: Persistence to Last Grade of Primary: Male: % of Cohort data remains active status in CEIC and is reported by World Bank. The data is categorized under Global Database’s Trinidad and Tobago – Table TT.World Bank.WDI: Education Statistics. Persistence to last grade of primary is the percentage of children enrolled in the first grade of primary school who eventually reach the last grade of primary education. The estimate is based on the reconstructed cohort method.; ; UNESCO Institute for Statistics; Weighted average; Each economy is classified based on the classification of World Bank Group's fiscal year 2018 (July 1, 2017-June 30, 2018).

Japan JP: Persistence to Last Grade of Primary: % of Cohort data was reported at 99.838 % in 2011. This records a decrease from the previous number of 99.931 % for 2010. Japan JP: Persistence to Last Grade of Primary: % of Cohort data is updated yearly, averaging 99.879 % from Dec 1971 (Median) to 2011, with 34 observations. The data reached an all-time high of 99.984 % in 2008 and a record low of 99.563 % in 1979. Japan JP: Persistence to Last Grade of Primary: % of Cohort data remains active status in CEIC and is reported by World Bank. The data is categorized under Global Database’s Japan – Table JP.World Bank: Education Statistics. Persistence to last grade of primary is the percentage of children enrolled in the first grade of primary school who eventually reach the last grade of primary education. The estimate is based on the reconstructed cohort method.; ; UNESCO Institute for Statistics; Weighted average; Each economy is classified based on the classification of World Bank Group's fiscal year 2018 (July 1, 2017-June 30, 2018).

Laos LA: Persistence to Last Grade of Primary: % of Cohort data was reported at 79.634 % in 2015. This records an increase from the previous number of 78.723 % for 2014. Laos LA: Persistence to Last Grade of Primary: % of Cohort data is updated yearly, averaging 63.113 % from Dec 1992 (Median) to 2015, with 22 observations. The data reached an all-time high of 79.634 % in 2015 and a record low of 53.133 % in 1993. Laos LA: Persistence to Last Grade of Primary: % of Cohort data remains active status in CEIC and is reported by World Bank. The data is categorized under Global Database’s Laos – Table LA.World Bank: Education Statistics. Persistence to last grade of primary is the percentage of children enrolled in the first grade of primary school who eventually reach the last grade of primary education. The estimate is based on the reconstructed cohort method.; ; UNESCO Institute for Statistics; Weighted average; Each economy is classified based on the classification of World Bank Group's fiscal year 2018 (July 1, 2017-June 30, 2018).

Aruba AW: Persistence to Last Grade of Primary: Female: % of Cohort data was reported at 85.216 % in 2020. This records a decrease from the previous number of 99.606 % for 2013. Aruba AW: Persistence to Last Grade of Primary: Female: % of Cohort data is updated yearly, averaging 95.278 % from Dec 1999 (Median) to 2020, with 10 observations. The data reached an all-time high of 99.606 % in 2013 and a record low of 85.216 % in 2020. Aruba AW: Persistence to Last Grade of Primary: Female: % of Cohort data remains active status in CEIC and is reported by World Bank. The data is categorized under Global Database’s Aruba – Table AW.World Bank.WDI: Social: Education Statistics. Persistence to last grade of primary is the percentage of children enrolled in the first grade of primary school who eventually reach the last grade of primary education. The estimate is based on the reconstructed cohort method.;UNESCO Institute for Statistics (UIS). UIS.Stat Bulk Data Download Service. Accessed April 5, 2025. https://apiportal.uis.unesco.org/bdds.;Weighted average;

Sao Tome and Principe ST: Persistence to Grade 5: Female: % of Cohort data was reported at 88.519 % in 2010. This records an increase from the previous number of 81.211 % for 2008. Sao Tome and Principe ST: Persistence to Grade 5: Female: % of Cohort data is updated yearly, averaging 75.694 % from Dec 2001 (Median) to 2010, with 7 observations. The data reached an all-time high of 88.519 % in 2010 and a record low of 65.369 % in 2001. Sao Tome and Principe ST: Persistence to Grade 5: Female: % of Cohort data remains active status in CEIC and is reported by World Bank. The data is categorized under Global Database’s Sao Tome and Principe – Table ST.World Bank: Education Statistics. Persistence to grade 5 (percentage of cohort reaching grade 5) is the share of children enrolled in the first grade of primary school who eventually reach grade 5. The estimate is based on the reconstructed cohort method.; ; United Nations Educational, Scientific, and Cultural Organization (UNESCO) Institute for Statistics.; Weighted average;