Discussion
ARIs, ARI
RECRUITMENT
Our ‘D-Kids’ RCT is the first to evaluate perinatal vitamin D supplementation against medically attended ARIs among Australian First Nations infants during the first year of life. The sample size of 314 infants is expected to provide 90% power to detect a 27.5% relative reduction in new ARI episodes between groups. Importantly, our mechanistic outcomes will further characterise the effects of vitamin D supplementation on infant immune function and respiratory microbiology.This ‘D-Kids’ trial has several strengths. It addresses ARIs, an unmet health need, particularly among socioeconomically disadvantaged children. The study premise is guided by vitamin D and ARI data specific to the target populationOf note, recent evidence suggests daily dosing is most effective clinically.There are also many challenges. The trial is being conducted throughout a pandemic. While the D-Kids trial has never officially paused, lockdowns, isolation and quarantine measures designed to reduce the spread of SARS-CoV-2 have restricted face to face contact, interaction with medical facilities and general travel, impacting participant recruitment and follow-up, and reducing the rates of ARI. As of December 2022, 184 infants had been recruited to the study. Several strategies have been implemented to mitigate slow recruitment including the addition of new study sites (notably Alice Springs in Central Australia), self-administered dosing, clinic assisted follow-up visits, and recruitment of twins and previously enrolled mothers. Notably, while self-administered dosing mimics the real-world setting, adherence (phone-based reporting) becomes more difficult to accurately monitor. With pandemic measures easing in 2023, we are optimistic about achieving our recruitment target.Feasible interventions such as vitamin D supplementation show considerable potential against ARI but more evidence is required. Our study outcomes will make an important contribution to clinical practice, the medical literature and could have profound implications for disadvantaged populations where ARIs are common.