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        <r:String xml:lang="sv">CATSS15 - The Child and Adolescent Twin Study in Sweden (15 years)</r:String>
        <r:String xml:lang="en">CATSS15 - The Child and Adolescent Twin Study in Sweden (15 years)</r:String>
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      <r:Content xml:lang="sv">CATSS översikt:

Tvillingstudien CATSS är en pågående longitudinell tvillingstudie som riktar sig till alla tvillingar födda i Sverige sedan 1 juli 1992. Sedan 2004 intervjuas tvillingföräldrar om barnens somatiska och psykiska hälsa och sociala miljö i samband med deras 9-årsdag (CATSS9). Vid 15 (CATSS15) och 18 (CATSS18) års ålder, fyller tvillingar och föräldrar i en webenkät som, förutom bedömningar av somatisk och mental hälsa, inkluderar mått på personlighetsutveckling och psykosocial anpassning. Vid 24 års ålder (CATSS24) fyller endast tvillingar i en webenkät som främst fokuserar på mental hälsa.

CATSS15:

CATSS15 startade 2010. Studien inkluderar alla 15-åriga tvillingar och deras föräldrar, oavsett om de deltagit i CATSS9 eller inte. Svarsfrekvensen ligger på 52% för tvillingarna och 48% för föräldrarna.  Urvalet består av enäggstvillingar samt tvåäggstvillingar av samma eller olika kön inom tvillingparet. Det totala antalet deltagande tvillingar (genom tvilling och/eller förälders deltagande) i CATSS15 är för närvarande ca 24 800 av 42 500 inbjudna (december 2025). Den kombinerade svarsfrekvensen ligger på 58%. I samband med CATSS15 får de som inte redan lämnat DNA via salivprov ett nytt erbjudande. Salivprovet används för zygositetsbestämning och genotypning. Antalet genotypade tvillingar i CATSS15 är för närvarande 15 500 (december 2025).

De frågeområden som ingår i CATSS15-enkäterna finns listade nedan. Detaljerad information om variabler finns på strdata.se.

Frågeområden föräldrar:

Administrativ Information
AUDIT - Alcohol Use Disorders Identification Test
CMRS - Child Mania Rating Scale
CMO - Child Monitoring
DUDIT - Drug Use Disorders Identification Test 
LSC-R - Life Stressor Checklist- Revised
PCR - Parent Child Relationship
PPCP - Parents' Perception of Child's Peers
PLE - Psychotic-like Experiences
Fysiska sjukdomar 
Fritidsaktiviteter
SDQ - Strength and Difficulties Questionnaire

Frågeområden tvillngar:

CMRS - Child Mania Rating Scale
DCQ - Dysmorphic Concerns Questionnaire
EDI-2 - Eating Disorder Inventory - 2
HRS-I - Hoarding Rating Scale-Interview
Fysisk aktivitet
PMS
PLE - Psychotic-like Experiences
Quality of Friendship 
RPQ - Reactive and Proactive Aggression Questionnaire
OBVQ - Revised Olweus Bully/Victim Questionnaire
SRD - Self-Reported Delinquency
Self-Reported Alcohol and Drug Use
Sexualitet
Fysiska sjukdomar 
SDQ - Strength and Difficulties Questionnaire
TCI - Temperament and Character Inventory
Tics
Vikt och längd</r:Content>
      <r:Content xml:lang="en">CATSS overview:

The Child and Adolescent Twin Study in Sweden (CATSS) is an ongoing longitudinal twin study targeting all twins born in Sweden since July 1, 1992. Since 2004, parents of twins are interviewed regarding the children's somatic and mental health and social environment in connection with their 9th birthday (CATSS-9). At age 15 (CATSS15) and 18 (CATSS18), twins and parents complete questionnaires that, in addition to assessments of somatic and mental health, include measures of personality development and psychosocial adaptation. At the age of 24 (CATSS24) only twins participate in a web survey that mainly focuses on mental health.

CATSS15:

CATSS15 started in 2010. The study includes all 15-year-old twins and their parents, regardless of whether they participated in CATSS9 or not. The response rate for the twin survey is 52% and for the parent survey it is 48%. The sample consists of both identical (monozygotic) and fraternal (dizygotic) twins, including same-sex and opposite-sex pairs. The total number of participating twins  (through parent and/or twin participation) in CATSS15 is currently 24,800 out of 42,500 invited (December 2025). The combined response rate is currently 58%. Participants who have not already provided a DNA sample via saliva are requested to do so again. The saliva sample is used for zygosity determination and genotyping. The number of genotyped twins in CATSS15 is currently 15,500 (December 2025). 

The question areas in the CATSS15 surveys are listed below. For detailed information about variables, visit strdata.se

Question areas in parent survey:

Administrative Information
AUDIT - Alcohol Use Disorders Identification Test
CMRS - Child Mania Rating Scale
CMO - Child Monitoring
DUDIT - Drug Use Disorders Identification Test 
LSC-R - Life Stressor Checklist- Revised
PCR - Parent Child Relationship
PPCP - Parents' Perception of Child's Peers
PLE - Psychotic-like Experiences
Somatic diseases
Spare time activites
SDQ - Strength and Difficulties Questionnaire

Question areas in twin survey:

CMRS - Child Mania Rating Scale
DCQ - Dysmorphic Concerns Questionnaire
EDI-2 - Eating Disorder Inventory - 2
HRS-I - Hoarding Rating Scale-Interview
Physical acitivity
PMS
PLE - Psychotic-like Experiences
Quality of Friendship 
RPQ - Reactive and Proactive Aggression Questionnaire
OBVQ - Revised Olweus Bully/Victim Questionnaire
SRD - Self-Reported Delinquency
Self-Reported Alcohol and Drug Use
Sexuality
Somatic diseases
SDQ - Strength and Difficulties Questionnaire
TCI - Temperament and Character Inventory
Tics
Weight and height</r:Content>
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