Vitamin D can be made in the skin by exposure to sunlight and can be found in certain foods. Vitamin D levels are alarmingly low in many North American children. Several health issues have been linked with low vitamin D. These include colds caused by viruses and asthma attacks. However, no study has determined whether vitamin D supplementation can reduce the risk of these conditions in young children where they are most common and most severe. The goals of this study are to determine whether wintertime high dose vitamin D supplementation of preschoolers can prevent colds and asthma attacks. The investigators also aim to work out how much money would be saved by the health care system and society if preschoolers were routinely supplemented with Vitamin D during the winter. The investigators believe that preschoolers receiving 'high dose' vitamin D supplementation during the wintertime will be less likely to have colds, asthma attacks, and low vitamin D levels and will be less likely to use the medical system and keep their parents away from work.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
QUADRUPLE
Enrollment
703
One drop per day (liquid), 400 IU, 4 to 9 months depending on date of enrollment and date of follow-up
One drop per day (liquid), 2000 IU, 4 to 9 months depending on date of enrollment and date of follow-up
St. Michael's Hospital
Toronto, Ontario, Canada
Hospital for Sick Children
Toronto, Ontario, Canada
Number of Laboratory confirmed upper respiratory tract infections
Parents of enrolled children will be asked to obtain a nasal swab from their child and complete a symptom checklist with each URTI. Reverse transcriptase polymerase chain reaction will be performed on each sample. Samples will be tested for 18 common respiratory viruses using the ID-TagTM RVP assay using the Luminex xMAPTM system.
Time frame: Up to 8 months
Number of parent reported upper respiratory tract infections
Parental reported URTI symptoms will be defined as two or more of fever, cough, runny nose, sore throat, headache, vomiting, feels unwell, muscle aches, ear ache or infection, poor appetite, not sleeping well, cranky/fussy, low energy or crying more than usual from a validated parent completed symptom checklist.
Time frame: Up to 8 months
Number of Asthma exacerbations
Asthma exacerbation will be defined as a wheezing episode in children with asthma as obtained from parent completed symptom checklist based on the International Study of Asthma and Allergies in Childhood (ISAAC).
Time frame: Up to 8 months
Serum vitamin D level
Blood for serum levels will be drawn by trained pediatric phlebotomists from for determination of 25-hydroxyvitamin D. Total 25-hydroxyvitamin D will be measured from serum samples using a competitive two-step chemiluminescence assay.
Time frame: 5-8months
Direct and indirect economic costs associated with upper respiratory tract infections
Cost-consequence and cost-effectiveness analyses will be conducted using data from this clinical trial. A societal perspective will be employed as both direct health service utilization costs as well as indirect costs to families from URTI will be calculated for the 400 IU per day versus 2000 IU per day groups.
Time frame: 16 months
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