Data Source

Registry

Type of Study

Longitude survey: long-term study of the same sample

Cross-section, regular

Cohort study

Historical studies of twin populations, bio-med data.

Data gathering method

Face-to-face interview (CAPI, PAPI)

Registries

Self-administered questionnaire

Biomed samples.

Ease

Available for the scientific community primarily by downloaded files in various applications.

Conditions of access

Formal agreements (e.g. fees, research contracts, institutional agreements, etc.)

As the STR is an (inter)national resource, the research team is receptive to collaboration with academic and industry-based researchers. Regardless of the type of research, all potential collaborations or data access agreements must be first reviewed by the Steering Committee of the STR (Swedish Twin Registry). If the applicant is not based at a Swedish university, we require that s/he has a collaborator based at a Swedish university. This is to assure that the Swedish research community benefits from their national resource. After approval by the STR Steering Committee, a contract will be drawn up, and data provided after a payment agreement is arranged.

Time elapsed between application and reception of data

Varies depending on type of request; between two and four months.

Type of available data (e.g. anonymised microdata, aggregated tables, etc.)

Types of requests for access include: 1. Aggregated summary tables or statistics from the STR. 2. Anonymised files of raw and/or transformed data from the STR. 3. Above data plus linkages to health registries. 4. Access to identifying information for further collection of new data.

Formats available

The data set is compatible to many applications such as Excel, SAS, SPSS, STATA, Text, etc.

Language issues

Information is available in Swedish and English.

Years of collection, reference years, and sample sizes

The Swedish Registry was established in the 1960s to study how smoking affects our health. At the time, little was known about the dangers of smoking. There is, at present, information on approximately 85,000 twin pairs, both monozygotic and dizygotic. There are currently about 30 ongoing projects based on the Swedish twin registry. The studies cover a wide range of public health issues, among others a focus on dementia diseases, allergies, cancer and cardiovascular diseases.

First year of collection

Various cohorts 1886, 1926, 1959

Stratification if applicable

Varies for different subsets.

Base used for sampling

All registered twins in the official statistics.

Geographical coverage and breakdowns

The whole country

Age range

No age restrictions (birth cohorts)

Statistical representativeness

Twins

Coverage of main and cross-cutting topics

At present, about 30 ongoing projects based on the twin registry cover a broad spectrum in public health. Some areas being investigated are ageing, dementia, allergies, cancer, and cardiovascular disease. Other projects are about the effects of gender differences on health and life situations. Ongoing projects About 70,000 twins in Sweden born before 1985 have recently responded to questionnaires or interviews. The twins answered questions about diseases they have/had and drugs they use. Now we are analysing the information. To estimate how genes or environment influence different diseases and behavior in childhood, we contact parents to all Swedish twins turning 9- or 12-years-old. More than 6,000 twins' parents have been contacted so far. We continue to interview new parents to the 9 year old. Another exiting project is Dementia in Swedish Twins (HARMONY). It concerns ageing and memory. The aim of this study is to investigate which factors affect our memory capacity and incidence of dementia.

Further Reading

• Andel, R., Crowe, M., Pedersen, N. L., et al. “Physical exercise at midlife and risk of dementia three decades later: A population-based study of Swedish twins.”Journal of Gerontology: Medical Sciences 63A (1) (2008): 62-66. • Bergvall, N., Lindam, A., Pawitan, Y., et al. “Importance of familial factors in associations between offspring birth weight and parental risk of type-2 diabetes.” International Journal of Epidemiology 37 (2008): 185-192. • Bruder, C., Piotrowski, A., Gijsbers, A., et al. “Phenotypically concordant and discordant monozygotic twins display different DNA copy number variation profiles.” The American Journal of Human Genetics 82 (2008): 763-771. • Eriksson, U. K., Gatz, M., Dickman, P., et al. “Asthma, eczema, rhinitis and the risk for dementia.” • Dementia and Geriatric Cognitive Disorders (25) (2008): 148-156. • Hallberg, J., Dominicus, A., Eriksson, U. K., et al. “Interaction between smoking and genetic factors in the development of chronic bronchitis.”Am J Respir Crit Care Med 177 (2008): 486-490. • Nordenstedt, H., Zheng, Z., Cameron, A. J., et al. “Postmenopausal hormone therapy as a risk factor for gastroesophageal reflux symptoms among female twins.” Gastroenterology 134 (2008): 921-928. • Svedberg, P., Johansson, S., Wallander, M.-A., & Pedersen, N. L. “No evidence of sex differences in heritability of Irritable Bowel Syndrome in Swedish twins.”Twin Research and Human Genetics 11(2), (2008): 197-203. • Yuh, J., Neiderhiser, J., Spotts, E., et al. “The role of temperament and social support in depressive symptoms: A twin study of mid-aged women.” Journal of Affective Disorders 106 (2008): 99-105. http://ki.se/ki/jsp/polopoly.jsp?d=9610&l=en

Standardisation

ICD

Possibility of linkage among databases

The Twin Registries are subject to rich inter-disciplinary collaborations with scientists both within and outside Sweden.

Breaks

STR has been developed over several years, but the fundamental structure is the same as from start. No major breaks.

Consistency of terminology or coding used during collection

High consistency in terminology.

Strengths The Swedish Twin Registry, managed by the Karolinska Institute, is the largest of its kind and has become an invaluable resource for medical research. It has a fundamental role for research on health, social bias and living conditions. More information available at: online.wsj.com/.../...yQjAxMTAyMDAwOTEwNDkyWj.html