Differential low uptake of free vitamin D supplements in preterm infants: the Quebec experience

BACKGROUND Vitamin D is essential for bone mineralization, particularly in premature infants. For nearly 20 years, Quebec has offered a program of free vitamin D supplements via its public medication insurance plan Régie de l'Assurance Maladie du Québec (RAMQ). The objective of this study is to evaluate the number of preterm infants that obtained at least one bottle (50 doses) of vitamin D supplement through this program and to determine if uptake varied by gestational age. METHODS This was a retrospective cohort study of preterm infants covered by RAMQ and born from 1998 to 2008; all infants had 1 year of follow-up data regarding supplement use. Data were extracted from the Quebec Pregnancy Cohort, a linked administrative database and were stratified by early (<34 weeks) or late gestational age premature infants. The number of infants obtaining supplements was the primary outcome and their characteristics were compared across gestational age groups. Predictors for participation (obtaining at least 1 bottle) or adherence (2 or more bottles) were identified via logistic regression (GEE). RESULTS 10288 infants were eligible; the percentage exposed to vitamin D was 24.5% (37.4%- early; 20.7%-late preterm infants, p < 0.001). The median number of bottles obtained was 2 for early and 1 for late preterms. For all premature infants, there was an apparent geometric decline in the infants obtaining subsequent bottles of supplements over the 12 month period. Additionally, there was a significant decline in program participation over time (OR = 0.90/year, 95% CI: 0.89-0.90) regardless of gestational age. Older or more educated mothers were positive predictors for participation. A prescription from a pediatrician significantly increased the odds of obtaining the supplement. CONCLUSION Early preterm infants were more likely to obtain the supplement post-discharge; uptake was low and decreased with time for both age categories. Specifically, targeting late preterm infants and young mothers with less education could improve vitamin D uptake.