TY - JOUR
T1 - Twins as Participants in Randomized Controlled Trials
T2 - A Review of Published Literature
AU - Sumathipala, Athula
AU - Yelland, Lisa
AU - Green, Debra
AU - Shepherd, Tom
AU - Jayaweera, Kaushalya
AU - Ferreira, Paulo
AU - Craig, Jeffrey M.
N1 - Funding Information:
JMC is supported by grants from the Australian National Health and Medical Research Council (grant number 1079102), the Financial Markets Foundation for Children (grant number 2015-111), the Cerebral Palsy Alliance Research Foundation (grant number PG2316), and by the Victorian Government's Operational Infrastructure Support Program. LNY is supported by an Australian National Health and Medical Research Council Early Career Fellowship (ID 1052388).
PY - 2018/2/1
Y1 - 2018/2/1
N2 - Monozygotic (MZ) and dizygotic (DZ) twins participate in research that partitions variance in health, disease, and behavior into genetic and environmental components. However, there are other innovative roles for twins in medical research. One such way is involving MZ and/or DZ twins in co-twin control-designed randomized controlled trials (RCTs). To our knowledge, no reviews have been conducted that summarizes the involvement of twins in RCTs. Therefore, we conducted a systematic literature search using the U.S. Clinical Trials Database, NHS electronic databases, MEDLINE, EMBASE, and PsychINFO for RCTs on publications involving MZ and/or DZ twins as RCT participants. Out of the 186,027 clinical trials registered in the U.S. clinical trial register ClinicaTrails.gov, only six RCTs used twins as participants. From 1,598 articles identified in our search, 50 peer-reviewed English language publications met our pre-defined inclusion criteria. Sample sizes for RCTs have ranged from a total number of participants from 2 to 1,162; however, 32 (64%) studies had a sample size of 100 or less, and of those, 12 (24%) had fewer than 10. Both MZ and DZ twins have been recruited to the RCTs. In most instances (33/50) each twin from a pair were assigned to different study arms. Most of those studies included MZ twins only. Despite the methodological advantages, the use of MZ and DZ twins as participants in interventional RCTs appeared limited. The continuous development of innovative twin designs, especially RCTs, indicates that twin research can extend beyond the more widely recognized heritability estimates.
AB - Monozygotic (MZ) and dizygotic (DZ) twins participate in research that partitions variance in health, disease, and behavior into genetic and environmental components. However, there are other innovative roles for twins in medical research. One such way is involving MZ and/or DZ twins in co-twin control-designed randomized controlled trials (RCTs). To our knowledge, no reviews have been conducted that summarizes the involvement of twins in RCTs. Therefore, we conducted a systematic literature search using the U.S. Clinical Trials Database, NHS electronic databases, MEDLINE, EMBASE, and PsychINFO for RCTs on publications involving MZ and/or DZ twins as RCT participants. Out of the 186,027 clinical trials registered in the U.S. clinical trial register ClinicaTrails.gov, only six RCTs used twins as participants. From 1,598 articles identified in our search, 50 peer-reviewed English language publications met our pre-defined inclusion criteria. Sample sizes for RCTs have ranged from a total number of participants from 2 to 1,162; however, 32 (64%) studies had a sample size of 100 or less, and of those, 12 (24%) had fewer than 10. Both MZ and DZ twins have been recruited to the RCTs. In most instances (33/50) each twin from a pair were assigned to different study arms. Most of those studies included MZ twins only. Despite the methodological advantages, the use of MZ and DZ twins as participants in interventional RCTs appeared limited. The continuous development of innovative twin designs, especially RCTs, indicates that twin research can extend beyond the more widely recognized heritability estimates.
KW - RCT
KW - randomization
KW - sample size
KW - twin research
UR - http://www.scopus.com/inward/record.url?scp=85042223554&partnerID=8YFLogxK
U2 - 10.1017/thg.2017.67
DO - 10.1017/thg.2017.67
M3 - Article
C2 - 29282159
AN - SCOPUS:85042223554
SN - 1832-4274
VL - 21
SP - 51
EP - 56
JO - Twin Research and Human Genetics
JF - Twin Research and Human Genetics
IS - 1
ER -