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        <r:String xml:lang="sv">CATSS9w - The Child and Adolescent Twin Study in Sweden (9 år, webbenkät)</r:String>
        <r:String xml:lang="en">CATSS9w - The Child and Adolescent Twin Study in Sweden (9 year, web questionnaire)</r:String>
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          <r:String xml:lang="sv">Karolinska Institutet</r:String>
          <r:String xml:lang="en">Karolinska Institutet</r:String>
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        <r:SimpleDate>2025-06-13</r:SimpleDate>
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      <r:Content xml:lang="sv">The Child and Adolescent Twin Study in Sweden (CATSS) är en pågående longitudinell tvillingstudie som riktar sig till alla tvillingar födda i Sverige. Mellan 2004 och 2019 kontaktades föräldrar till 9-åriga tvillingar och bjöds in att delta i CATSS9. Data samlades in genom telefonintervjuer. År 2020 övergick insamlingen till webbenkäter, vilket innebar en viss omarbetning av innehållet i intervjufrågorna. För att markera denna övergång och de förändrade frågorna, kallas enkäten nu CATSS9w. Fokus ligger fortsatt på fysiska och psykiska hälsoproblem samt beteenden som fysisk aktivitet och social interaktion.  

Tvillingarna i CATSS9w är födda från 2011 och framåt. Urvalet inkluderar både enäggs- och tvåäggstvillingar av samma eller olika kön inom tvillingparet.  För närvarande deltar 8 500 tvillingar (december 2025) av 17 400 inbjudna, vilket ger en svarsfrekvens på 49%.

I samband med CATSS9w-enkäten får föräldrarna även en förfrågan om att lämna DNA via salivprov från tvillingarna.  Dessa prover används för zygositetsbestämning och genotypning. Antalet genotypade tvillingar som deltagit i CATSS9w är 2 500 (december 2025). Föräldrarna får också en förfrågan om att delta i en studie om fysisk aktivitet där tvillingarna bär en accelerometer under en vecka. 

De frågeområden som ingår i CATSS9w-enkäten finns listade nedan. Detaljerad information om variabler finns på strdata.se.

Administiv information
Vikt och längd
Demografi
Fysisk aktivitet
Sjukdomar
Astma, eksem och hösnuva
SDQ - Strength and difficulties questionnaire
ADHD
A-TAC - Autism - Tics, ADHD och andra komorbiditeter (endast Autism-frågorna)
Språkutveckling
LSC-R - Life Stressor Checklist- Revised
Covid19</r:Content>
      <r:Content xml:lang="en">The Child and Adolescent Twin Study in Sweden (CATSS) is an ongoing longitudinal twin study targeting all twins born in Sweden. Between 2004 and 2019, parents of 9-year-old twins were contacted and invited to participate in CATSS9. Data was collected through telephone interviews. In 2020, the data collection method transitioned to web-based questionnaires, which involved some revisions to the interview questions. To mark this transition and the revised questions, the survey is now referred to as CATSS9w. The focus remains on various physical and mental health issues as well as behaviors such as physical activity and social interaction. 

The twins in CATSS9w are born from 2011 onwards. Both identical (monozygotic) and fraternal (dizygotic) twins of the same or opposite sex within the twin pair are included. Currently, 8,500 twins (as of December 2025) are participating out of 17,400 invited, resulting in a response rate of 48%.

In conjunction with the CATSS9w survey, parents are also asked to provide DNA samples via saliva from the twins. These sample are used for zygosity determination and genotyping. The number of genotyped twins who have participated in CATSS9w is 2,500 (as of December 2025). Parents are also asked to participate in a study on physical activity, where the twins wear an accelerometer for one week.

The question areas included in the CATSS9w survey are listed below. Detailed information about the variables can be found at strdata.se.

Administrative Information
Weight and height
Demography
Physical activity
Diseases
Asthma, Eczema and Hayfever
SDQ - Strength and Difficulties Questionnaire
ADHD
A-TAC - Autism - Tics, ADHD and other Comorbidities inventory (only Autism-questions)
Language development
LSC-R - Life Stressor Checklist- Revised
Covid19</r:Content>
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