Conducting Clinical Trials in Twin Populations: A Review of Design, Analysis, Recruitment and Ethical Issues for Twin-Only Trials

A Pilot Single-Site Randomized Control Trial: Investigating the Use of Donor Milk in Late Preterm and Term Infants in the Neonatal Intensive Care Unit

OBJECTIVE

We aimed to study donor milk (DM) supplementation when mother's own milk (MOM) was unavailable in term and late preterm infants (LPIs) admitted to the neonatal intensive care unit (NICU). We hypothesized that this study would be feasible, defined by the rate of consent, diet adherence, and study completion. We further hypothesized that compared with formula supplementation, DM supplementation, for no longer than 7 days from birth, would be associated with an increase in breastfeeding attempts and the percentage of MOM (MOM%) without adversely affecting growth. Breastfeeding attempts and MOM% were assessed over 48 hours at the end of the intervention, which was defined as NICU discharge or at the end of supplementation, whichever came sooner.

STUDY DESIGN

This was a pilot study (n = 32). Infants with a gestational age > 34 weeks admitted to the NICU were included. Infants were randomized to one of two groups: human milk (MOM + DM) or formula (MOM + F).

RESULTS

The consent rate was 52%. Adherence to the study diet was 97%, and completion was 100%. When the MOM + DM group was compared with the MOM + F group, there was no difference in breastfeeding attempts (median [interquartile range]: 3.5 [1.5-6] vs. 1.5 [0.5-4] times, p = 0.1) or MOM% (60 vs. 59%, p = 0.9). Weight and length at multiple time points were similar when the groups were compared.

CONCLUSION

A study randomizing term and LPIs in the NICU to DM or formula when MOM was unavailable is feasible. It remains unclear if DM improves breastfeeding success in this population.

KEY POINTS

· A study that randomizes term and late preterm infants in the NICU to DM or formula supplementation when mother's own milk is not available is feasible.. · It remains unclear if DM compared to formula supplementation improves direct breastfeeding.. · In general, growth was similar in infants who received DM or formula as a supplement..

Brazilian Twin Studies: A Scoping Review

The current study was motivated by an interest in deepening understanding of Brazilian twin research, which is underrepresented internationally, in an effort to rectify this situation. Our aim was threefold: (1) to carry out a comprehensive investigation of Brazilian research on twins according to the area of knowledge; (2) to evaluate the representation of research in the field of psychology in comparison with other areas; (3) to evaluate characteristics of the research that may have contributed to its exclusion from the comprehensive meta-analysis of 50 years of twin research. A scoping review was performed according to PRISMA guidelines. Titles and abstracts were searched up to 2022 in six databases: CAPES, BDLTD, PePSIC, PubMed, Google Scholar, and SciELO, using selected keywords both in Portuguese and in English (e.g., 'twins' and 'Brazil'; 'twinning' and 'Brazil'; 'gemelaridade' [twinning], and 'gêmeos' [twins]). Three hundred and forty publications were included in the review. Approximately half (53.8‰) used the classic twin design to investigate the heritability of several traits, and the other half (46.2%) used other research designs. The scoping review showed that the number of publications doubled approximately every 10 years. Most publications were from the health area, with medicine accounting for approximately half of the studies, followed by psychology, odontology, and biology. We found that the interest in studying twins among Brazilian scientists is increasing over the years and there are reasons to be enthusiastic about the potential impact of this trend in the global scenario.

Accounting for Twins and Other Multiple Births in Perinatal Studies Conducted Using Healthcare Administration Data

The analysis of perinatal studies is complicated by twins and other multiple births even when they are not the exposure, outcome, or a confounder of interest. Common approaches to handling multiples in studies of infant outcomes include restriction to singletons, counting outcomes at the pregnancy-level (i.e., by counting if at least one twin experienced a binary outcome), or infant-level analysis including all infants and, typically, accounting for clustering of outcomes by using generalised estimating equations or mixed effects models. Several healthcare administration databases only support restriction to singletons or pregnancy-level approaches. For example, in MarketScan insurance claims data, diagnoses in twins are often assigned to a single infant identifier, thereby preventing ascertainment of infant-level outcomes among multiples. Different approaches correspond to different causal questions, produce different estimands, and often rely on different assumptions. We demonstrate the differences that can arise from these different approaches using Monte Carlo simulations, algebraic formulas, and an applied example. Furthermore, we provide guidance on the handling of multiples in perinatal studies when using healthcare administration data.

A Pilot Single-Site Randomized Control Trial: Investigating the Use of Donor Milk in the Late Preterm and Term Infant in the Neonatal Intensive Care Unit

Objective : We aimed to study the use of donor milk (DM) in term and late preterm infants (LPIs) when mother’s own milk (MOM) was unavailable. We hypothesized this study would be feasible and breastfeeding attempts and the percentage of MOM (MOM%) would increase with DM without adversely affecting growth. Study Design : This was a pilot study (n=32). Infants with gestational age >34 weeks admitted to the neonatal intensive care unit were included. Infants were randomized to: the human milk (MOM+DM) or formula (MOM+F) groups. Result : Consent rate was 52%. Breastfeeding attempts increased significantly over time in the MOM+DM group compared to the MOM+F group (group p=0.41, time p =0.02, group*time p=0.01) . Growth at multiple time points was similar when the two groups were compared. Conclusion : A study randomizing term infants and LPIs to DM or formula when MOM is unavailable is feasible. DM may increase breastfeeding attempts without compromising growth.