Effect of High-Dose vs Standard-Dose Wintertime Vitamin D Supplementation on Viral Upper Respiratory Tract Infections in Young Healthy Children

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Aglipay M, et al. "Effect of High-Dose vs Standard-Dose Wintertime Vitamin D Supplementation on Viral Upper Respiratory Tract Infections in Young Healthy Children". JAMA. 2017. 318(3):245-254.
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Clinical Question

Does high-dose vs standard-dose vitamin D supplementation reduce the incidence of viral upper respiratory tract infections in young children during the winter?

Bottom Line

Daily administration of high-dose compared to standard-dose vitamin D does not reduce URIs in young children in the wintertime.

Major Points

Prior studies suggested a link between low vitamin D levels and frequency of viral URIs. This study specifically looked at the incidence of viral URIs in young children during the wintertime and no association between dose of vitamin D and URI frequency (primary outcome) was found, nor in the secondary outcomes of median time to first laboratory-confirmed infection, number of parent-reported URIs between groups despite a significant difference in the serum values of vitamin D between the two groups at the end of the study.

Guidelines

Design

  • Multisite, double-blind, randomized, parallel group
  • N=703
    • High-dose (n=354)
    • Standard-dose (n=349)
  • Setting: Toronto, Ontario, Canada (latitude 43 north)
  • Enrollment: Winter seasons of 2011 to 2015; a child could only be randomized in to the trial during one winter season
  • Mean follow-up: 6.2 months
  • Analysis: Intention-to-treat
  • Primary outcome: number of laboratory-confirmed viral upper respiratory tract infections based on on parent-collected nasal swabs over winter months
  • Secondary outcomes: number of influenza infections, noninfluenza infections, parent-reported URIs, time to first URI, and serum vitamin D levels at study termination

Population

Inclusion Criteria

  • Children who had well child checkups between September through November at a primary care research network of 8 pediatric or family medicine group practices participating in TARGet Kids! in Toronto
  • Healthy children aged 1 to 5 years

Exclusion Criteria

  • Gestational age younger than 32 weeks
  • Chronic illness (other than asthma)

Baseline Characteristics

  • Standard-dose group
    • Girls: 39%
    • Mean age: 2.8 years
    • Mean 25-hydroxyvitamin D level: 36.9
    • Average minutes in unstructured free play outdoors per week: 60
    • Mean weight: 14.7kg
  • High-dose group
    • Girls: 45%
    • Mean age: 1.5 years
    • Mean 25-hydroxyvitamin D level: 35.9
    • Average minutes in unstructured free play outdoors per week: 35
    • Mean weight: 13.9kg

Interventions

  • Radomized to standard-dose (400 IU/day) or high-dose (2000 IU/day)
    • Parents were instructed to administer 1 drop of the solution (Kids Ddrops containing Vitamin D3) daily into their child's mouth
  • Baseline vitamin D levels were drawn
  • Over the counter vitamin D medicines were prohibited
  • Parents completed a symptom checklist during the winter months
  • Parents collected viral nasal swabs for every URI, with monthly phone calls for reminding
    • Parents were not required to visit the physician to report the URI
  • Between April and May the following year (4-8 months after randomization) a follow-up data collection and vitamin D level was completed in the office

Outcomes

Comparisons are intensive therapy vs. standard therapy.

Primary Outcomes

Primary outcome
##% vs. ##% (HR ##; 95% CI ##-##; P=##)

Secondary Outcomes

Subgroup Analysis

Adverse Events

Criticisms

Funding

Further Reading