Prevention of Vitamin D Deficiency Following Pediatric CHD Surgery: a Phase II Dose Evaluation Randomized Controlled Trial Comparing Usual Care With a High Dose Pre-operative Supplementation Regimen Based on the Institute of Medicine Daily Upper Tolerable Intake Level
Prevention of Vitamin D Deficiency Following Pediatric CHD Surgery: a Phase II Dose Evaluation Randomized Controlled Trial Comparing Usual Care With a High Dose Pre-operative Supplementation Regimen Based on the Institute of Medicine Daily Upper Tolerable Intake Level
Our research group has shown that almost all children with congenital heart disease (CHD) are
 vitamin D deficient following heart surgery. This work strongly suggests that the vitamin D
 intake presently recommended for healthy children, and also given to children with CHD, is
 inadequate to prevent vitamin D deficiency following surgery. Unfortunately, there have been
 no studies investigating any other vitamin D dose in children with heart disease. Recently, a
 higher dose of vitamin D intake has been approved (by the Institute of Medicine and Health
 Canada) and recent work on healthy children has shown it to be safe. The objective of this
 study is to determine whether this recently approved higher dose of vitamin D can safely
 reduce the number of children who are vitamin D deficient following surgery. This dose
 evaluation study will also evaluate whether it is possible to perform a large study (across
 Canada) to determine whether vitamin D supplementation can improve outcomes following
 surgery. It is hypothesized that a daily high dose vitamin D regimen, modeled on the
 Institute of Medicine daily upper tolerable intake level (UL), will significantly reduce
 vitamin D deficiency following CHD surgery, when compared with usual intake.
1 - INTRODUCTION 1.1 Summary of problem CHD is a common condition with an estimated
 prevalence of 1 per 100 in the general population. A significant proportion of these
 pediatric patients require one or more corrective surgeries over their lifetime, leading to
 15000 procedures per year in North America. Post-operatively, these patients suffer
 significant morbidities which may include a pronounced systemic inflammatory response,
 coagulopathy, respiratory failure, electrolyte disturbances, arrhythmia, myocardial
 dysfunction, kidney failure, infection and endocrine imbalances. Interventions that prevent
 or modulate post-operative pathophysiology may prevent illness, speed recovery and decrease
 chronic morbidity in this high risk pediatric population. Vitamin D is recognized as a
 pleiotropic hormone important for the functioning of multiple organ systems, including those
 central to critical illness pathophysiology. Recent research by our group and others has
 documented not only that 4 out of every 5 CHD patients have inadequate blood levels of
 vitamin D following surgery, but an association between immediate post-operative hormone
 levels and clinical course. Altogether, these findings and similar results in adult critical
 care and cardiac surgery populations, suggest that optimization of vitamin D status following
 CHD repair could lessen inflammation, reduce nosocomial infection and improve cardiac
 function. As an inexpensive medication (~$15/month) that is generally regarded as safe,
 vitamin D has the potential to be an ideal intervention for improving outcomes following CHD
 repair. Clinical trials will be required to determine whether elevation of pre-operative
 25-hydroxyvitamin D (25OHD) and prevention of post-operative vitamin D deficiency improves
 the health of patients with CHD who require cardiac surgery.

 1.2 - Gaps in current knowledge regarding vitamin D supplementation in CHD

 The current body of knowledge suggests that optimization of vitamin D status prior to and
 following CHD repair could improve outcomes through reduced inflammation, fewer nosocomial
 infections and improved cardiac function. However, before these findings can be translated
 into clinical practice a number of unknowns must be addressed:

 1. Evidence of benefit from interventional studies - As a unique and under-appreciated
 problem, there have been no interventional studies establishing that prevention of
 post-operative vitamin D deficiency improves clinical outcomes in CHD patients.

 2. Lack of studies evaluating vitamin D dosing in the CHD population - Attempts to perform
 a large randomized control trial (RCT) would be premature as a dosing regimen that
 prevents post-operative vitamin D deficiency has not yet been identified. Moreover,
 there have been no vitamin D dosing studies or guidelines developed specific to the CHD
 population; presently children with CHD receive the same advice regarding
 supplementation as healthy children.

 3. The safety of vitamin D doses above usual care has not been studied in the CHD
 population - Although it is tempting to extrapolate recent safety data from high dose
 vitamin D studies on healthy children to the CHD population, this may be inappropriate.
 CHD patients have unique metabolic demands, organ dysfunctions, and known and unknown
 genetic abnormalities that potentially make them more or less susceptible to vitamin D.

 To begin addressing these knowledge gaps we will complete a pilot dose evaluation trial with
 the goal of identifying a supplementation regimen that safely prevents post-operative vitamin
 D deficiency.

 2 - OBJECTIVES AND HYPOTHESIS 2.1 Hypothesis Pre-operative supplementation with a daily high
 dose vitamin D regimen, modeled on the Institute of Medicine (IOM) daily upper tolerable
 intake level (UL), will significantly reduce vitamin D deficiency following CHD surgery, when
 compared with usual intake.

 2.2 Study objectives Primary study objective: In pediatric patients with CHD, determine
 whether a pre-operative regimen of daily high dose vitamin D results in a significant
 reduction in post-operative vitamin D deficiency, when compared with usual care

 Secondary study objectives:

 1. Determine whether a pre-operative regimen of daily high dose vitamin D, compared with
 usual care, results in vitamin D related adverse events (hypercalcemia, hypercalciuria).

 2. Determine whether a pre-operative regimen of daily high dose vitamin D, compared with
 usual care, improves established markers of vitamin D axis functioning (active hormone
 levels, cardiac function).

 3. Determine the barriers and feasibility of an RCT evaluating whether vitamin D
 supplementation improves clinical outcomes in children who require CHD surgery.

 3 - METHODOLOGY 3.1 Study design and rationale - We will perform a pilot double blind
 randomized controlled dose evaluation trial comparing the efficacy and safety of two vitamin
 D dosing regimens in the prevention of post-operative vitamin D deficiency in children
 undergoing surgery for CHD.

 3.2 Proposed supplement doses (Interventions) to be tested and rationale - Treatment groups -
 The doses for evaluation have been modelled on the two age specific intake levels recommended
 by the IOM. Infants under 6 months of age in the high dose group will receive 600 IU/day more
 than the IOM recommended UL, while those between 6 and 12 months will receive 100 IU/day more
 than UL.

 Usual care group will receive Adequate Intake (AI) for infants and Recommended Dietary
 Allowance (RDA) for children over 1 year. These doses were chosen by IOM to achieve blood
 25OHD levels above 50 nmol/L in the majority of the healthy population.

 High dose group is based on the age-specific UL. These doses were chosen to elevate 25OHD
 well above 50 nmol/L, while minimizing risk of vitamin D toxicity (e.g. hypercalcemia,
 hypercalciuria).

 3.3 Anticipated pre- and post-operative 25OHD levels in the study arms - Given the 40%
 intra-operative decline, pre-operative levels above 90 nmol/L will be required to maintain
 post-operative levels above 50 nmol/L (the value at which sufficient substrate to synthesize
 the active metabolite is available). The ability of certain vitamin D intake levels to
 achieve this pre-operative value can be inferred from recently completed dosing studies on
 healthy children level. These studies, including one by co-investigator (Dr. Hope Weiler,
 McGill) have shown that usual care dosing for 2 to 3 months will achieve pre-operative levels
 of 90 nmol/L in only 40-50%. In contrast, studies evaluating doses approximating our higher
 daily intake level (1600 IU/day ) achieved mean 25OHD levels of 130 to 150 nmol/L; suggesting
 that 80% of CHD patients could achieve pre-operative levels of 90 nmol/L or above.

 3.4 Study design details 3.4.2 Stratification: We anticipate that two months of daily
 consumption may be required to achieve target 25OHD levels. Participants will be stratified
 into whether or not they are expected to receive at least 8 weeks of study drug prior to
 surgery. This stratification should guarantee that an equal number of CHD patients who will
 not receive 8 weeks of oral dosing end up in both the high and low dose arms. We will further
 stratify by the age (under or over 1 year of age) 3.4.3 Randomization and allocation
 concealment: Computer software generated randomization will be performed. Given the expected
 recruitment (4 to 5 per month) and potential impact of season on 25OHD randomization will be
 performed in blocks (4 within each strata). Only the pharmacy staff will be aware which
 patients receive high and low dose.

 3.4.4 Blinding: We will blind patients, families, investigators, hospital staff, and research
 personnel to treatment arm. The two interventions will be indistinguishable (vial, volume,
 color, taste, consistency and smell). Only the pharmacist will know the identity of the study
 drug administered to a specific patient. Blinding can be broken at the request of the
 clinical service.

 3.4.5 Co-interventions: The study protocol will not protocolize co-interventions as the study
 is single centre and CHEO has protocols or standardized approaches to the common
 post-operative complications and adverse events.

 3.5 Study procedures 3.5.1 Recruitment: Potentially eligible study participants will be
 identified in the ambulatory clinics (cardiology, cardiovascular) or inpatient wards
 (including pediatric intensive care and neonatal intensive care unit). CHD patients
 identified as requiring surgery and have or will be referred to the cardiovascular team for
 consultation may be provided a patient brochure directly by hospital staff or as part of the
 standard information package (mailed to outpatients). Caregivers (and children where
 appropriate) will be asked for permission to be approached about study participation by the
 research nurse/assistant.

 3.5.2 Study drug distribution: Europharm has agreed to provide the study drug in the required
 concentrations, prepared in indistinguishable vials for blinding purposes. Pharmacy will
 administer study drug (based on randomization, participant age and whether the patient is
 breast or formula fed). Infants with CHD assigned to the usual care arm will be given a
 placebo (0 IU/mL) as they will receive usual (recommended) vitamin D intake as part of
 formula.

 3.5.3 Frequency and duration of follow-up appointments Planned additional study appointments-
 There will be no additional appointments planned for study purposes. Patients may require
 additional appointments if research tests identify clinically relevant findings.

 Planned additional study phone calls - Research study staff will call caregivers and
 participants (where applicable) every two to four weeks to encourage compliance and provide
 education.

 3.5.4 Frequency of biological sample collection and metabolites measured Before initiation of
 study drug - Urine - After consent is obtained and the study participant is waiting for the
 pharmacy to prepare the study drug we will gather a urine sample for determination of
 calcium:creatinine ratios. Where developmentally appropriate the participants will be asked
 to provide urine into a container. Urine bags will be placed on younger children.

 Blood - Neonates and other study participants (mainly inpatients) requiring surgery within 2
 months of diagnosis and enrollment will have blood collected prior to (or within 2 days) of
 starting study supplement for determination of 25OHD. These patients will not have blood
 collected for research purposes again until they are taken to the operating room.

 During period of study drug administration - Blood - For those study participants who will
 receive study drug for more than 6 months we will measure 25OHD and calcium at the time of
 clinically indicated blood-work during regularly scheduled cardiology or cardiovascular
 surgery (CVS) clinic appointments At time of standard pre-surgical blood work - All
 outpatient participants will have blood collected at the time of standard pre-surgical blood
 work in preparation for the operation (two to three weeks prior to surgery). The blood will
 be sent to the CHEO laboratory for measurement of 25OHD and ionized calcium. Once completed,
 results will be forwarded to safety officer and study investigator (sealed).

 Intraoperative biological samples and measurements- Blood - All study participants will have
 2 mL of blood collected in the operating room following anesthesia and intubation, but prior
 to skin incision and initiation of cardiopulmonary bypass. Blood will also be sent to the
 CHEO laboratory for pre-operative ionized calcium determination. Remaining sample will be
 aliquoted and stored at -80 degrees Celsius (oC).

 Urine - All study participants will have urine collected after insertion of the urinary
 catheter. The sample will be sent to the CHEO laboratory for determination of
 calcium:creatinine ratio. Study results will not appear on the patient hospital chart, but
 will be labeled with the study identification (ID) number and forwarded to the study
 investigator and safety officer for review.

 Post-operative biological samples and other study measurements Blood - All study participants
 will have 2 mL of blood collected following separation from cardiopulmonary bypass (at
 admission to PICU). Further study participants will have 2 mL of blood collected on
 post-operative days 1, 3, 5 and 10 in the PICU. Samples will be collected from arterial or
 central venous catheters at the time of clinically indicated blood work. If these catheters
 have been removed, blood will be collected at the time of clinically indicated venipuncture.
 If patients are discharged to the ward before the day 10 research sample is collected a
 discharge sample will be collected at the time of discharge and no further research blood
 will be gathered.

 Urine - All study participants will have urine collected from the urinary catheter on the
 first post-operative day. The samples will be sent to the CHEO laboratory for determination
 of calcium and creatine concentrations.

 Echocardiography - A comprehensive exam will be performed immediately post-operatively
 (standard of care) and on the first post-operative day by a trained technician or pediatric
 cardiologist.

 Case report form

 1. Questionnaire - On the day of surgery the research coordinator will collect the
 participant dairies and unused study supplement. Information will also be collected on
 prescribed medications, nutrition, and additional supplement use.

 2. Operative details - The research assistant will extract detailed operative information,
 including: cardiac lesion type, surgery performed, Risk Adjusted Congenital Heart
 Surgery (RACHS) score, total fluid intake and output, blood product and fluid
 administration and loss, hypothermia, need for deep hypothermic circulatory arrest
 (duration), aortic cross clamp times, cardiopulmonary bypass (CPB) circuit volumes, CPB
 circuit constituents, CPB time, occurrence of intraoperative hyper or hypocalcemia,
 administration of parenteral calcium, need for catecholamines following separation from
 CPB, occurrence of intra-operative arrhythmias.

 3. PICU course - Clinically relevant information on clinical course and organ dysfunction
 will be collected, including: death, extracorporeal membrane oxygenation (ECMO), PRISM
 illness severity, cardiovascular dysfunction (fluid bolus requirements,
 inotrope/catecholamine use, arrhythmia), renal dysfunction (urine output, creatinine
 measurements, need for dialysis), hypocalcemia and calcium administration, duration of
 mechanical ventilation and duration of PICU stay.

 3.5.5 Other metabolites and measurements on research specimens Remaining research blood will
 be used for research purposes only (measurement of antimicrobial peptides, cytokines,
 nutritional markers).

 4 -STUDY SAFETY MEASURES 4.1 Background on vitamin D safety and toxicity Acute vitamin D
 toxicity is characterized by hypercalcemia or hypercalciuria, with the classic symptoms
 directly attributable to these abnormalities. Acute toxicity is a rare event that occurs in
 the context of overdose (accidental or prescribed megadoses in the range of 300,000-600,000
 IU). The risk of acute vitamin D toxicity with this study is remote as it would require
 consumption of more than one vial of study drug to meet doses (~150,000 IU) and blood 25OHD
 levels known to cause toxicity.

 Vitamin D toxicity due to genetic susceptibility - Concern about the safety of daily high
 dose vitamin D supplementation dates back to the 1950's when a rise in idiopathic infantile
 hypercalcemia (IIH) coincided with the implementation of higher daily vitamin D intake (~4000
 IU/day). This small epidemic lead to a decrease in recommended daily vitamin D intake to
 levels that could prevent rickets and hypocalcemic seizures (400 IU/day). It is now thought
 that most cases of IIH are due to rare genetic conditions (1:10000) that increase
 susceptibility to vitamin D. Of these, patients with William's syndrome can have CHD as part
 of the constellation of symptoms and the proposed project will exclude these individuals.

 Lack of subacute/chronic toxicity with IOM high dose in healthy children - Given recent
 suggestions that higher vitamin D levels might protect against non-bone disease, the safety
 of vitamin D doses above usual care (400-600 IU/day) has been reconsidered. To address this
 question the American and Canadian governments had the IOM assemble a committee of experts to
 provide recommendations based upon a comprehensive review of literature. In the final IOM
 report an age specific daily upper tolerable intake level was provided that was intended to
 safely elevate 25OHD levels while avoiding toxicity. Recently two blinded RCTs have shown
 that vitamin D supplementation at and slightly above the IOM daily upper tolerable intake
 level does not cause hypercalcemia or hypercalcuria. It is important to acknowledge that the
 IOM recommendations are for healthy children and may not be applicable to children with CHD
 4.2 Safety measures and clinically relevant research findings Pre-surgical 25OHD and ionized
 calcium levels -

 To avoid vitamin D overdose, hypercalcemia and side effects we have selected a supplement
 level recently proven to be safe in healthy children and will target the period of high dose
 supplementation to 6 months, and no more than 12 months. Further, to avoid excessive vitamin
 D levels at time of surgery we will measure 25OHD and ionized calcium with the pre-surgical
 blood work (~3 weeks prior to surgery for outpatients who will receive many months of
 supplementation). These values will be determined through the CHEO laboratory with results
 forwarded to the study investigator and safety officer. Study participants with elevated
 blood calcium and/or vitamin D levels will be identified and contacted by the safety officer.
 Ionized calcium thresholds have been established. For 25OHD, although 500 nmol/L is generally
 considered the definitive toxicity threshold, we have chosen to intervene with 25OHD levels
 above 200 nmol/L as this value is supraphysiological and exceeds our study goal. The
 following details the actions that will be taken with abnormal values:

 1. For 25OHD above 200 nmol/L with evidence of hypercalcemia (vitamin D toxicity):
 discontinue study drug immediately, repeat the values (fasting), and refer to
 endocrinology.

 2. For 25OHD above 200 nmol/L without hypercalcemia: study drug will be reduced by 50% (c)
 For 25OHD above 250 nmol/L, without hypercalcemia: study drug will be discontinued (d)
 For hypercalcemia with 25OHD under 200 nmol/L: repeat the bloodwork (fasting) and refer
 to endocrinology Pre-surgical 25OHD and ionized calcium levels during period of study
 drug administration. For patients who will receive more than 6 months of study drug
 prior to surgery we will determine blood 25OHD and ionized calcium at the time of
 routine bloodwork at CVS and cardiology appointments (or hospitalizations)
 Post-operative blood calcium levels. Will be determined at multiple times following
 cardiac surgery and represents standard of care. Both hypo and hypercalcemia will be
 managed by the clinical team as required. Study participants with persistently elevated
 blood calcium levels (for more than two days, not explained by intravenous calcium
 administration) will be referred to endocrinology.

 Post-treatment, pre-operative elevated urine calcium:creatinine ratios - As prolonged
 exposure to hypercalciuria (> 3 months) could theoretically cause nephrocalcinosis we
 will have ultrasounds performed prior to hospital discharge on all patients with
 elevated immediate pre-operative urine calcium to creatinine ratios. Any study
 participant with nephrocalcinosis will be referred to the CHEO nephrology service for
 further assessment. It is important to note that with the exception of a decrease in
 vitamin D dose to minimal daily intake (will occur by default in all patients) there
 would be no additional treatment for nephrocalcinosis at this time. Dr. Geier has
 offered to see these patients at no expense.

 Post-operative elevated urine calcium:creatinine ratios - Urine calcium to creatinine
 ratios are not measured as part of standard medical care. Further no research is
 available to indicate the impact of CHD and operative procedures on acute post-surgical
 calcium excretion or long-term nephrocalcinosis risk. However, as this patient
 population is followed closely and nephrocalcinosis is rarely reported following CHD
 surgery (only one case series of 3 in the literature) it does not appear that these
 patients are at significant risk for nephrocalcinosis. However, the addition of higher
 doses of vitamin D could predispose to nephrocalcinosis given concurrent acute illness,
 immobilization and diuretic use. Therefore any patient with an elevated calcium:
 creatinine ratio (collected on the first post-operative day) will be referred to
 nephrology service. Again, Dr. Geier has offered to consult on these patients; he will
 repeat the calcium: creatinine ratio and decide upon further investigation.

 Participants that have study drug discontinued or decreased will be retained in the
 study, have peri-operative biological samples collected as outlined, and will be
 included in the analysis using intention to treat methodology.

 4.3 Study results of unclear clinical relevance 4.3.1 Post-operative vitamin D Low risk
 of elevated post-operative vitamin D - As described, vitamin D levels will be checked 2
 to 3 weeks prior to surgery. For patients with even moderate elevations in 25OHD (above
 200 nmol/L) study drug intake will be modified to ensure vitamin D levels do not exceed
 250 nmol/L in any individual at the time of surgery. Given these pre-operative safety
 measures and the known 40% intraoperative drop, we anticipate that no study participant
 will have a vitamin D level above 250 nmol/L post-operatively. Even if a participant was
 to have unexpectedly high 25OHD value, no treatment would be initiated without evidence
 of hypercalcemia (note - patients with persistent post-operative hypercalcemia would be
 referred to endocrinology as outlined in section 4.1). Further, the management plan for
 a post-operative patient with 25OHD in excess of 200 nmol/L would be to discontinue high
 dose study supplement. As all study participants will discontinue study drug at time of
 surgery, any patient with elevated 25OHD will already be receiving the appropriate
 management.

 Unclear relevance of low post-operative Vitamin D - Observational studies suggest that
 low post-operative vitamin D contributes to a more protracted clinical course. However,
 it is presently unclear whether or how to acutely increase 25OHD in post-operative CHD
 patients as there is no intravenous form and the safety of single enteral megadoses of
 vitamin D (>100,000 IU) has not been proven in any diseased pediatric population. With
 the exception of those participants with endocrinology consults initiated (for
 hypercalcemia) all patients will be encouraged to continue with standard vitamin D
 supplementation following surgery (infants 400 IU, children 600 IU). This intake will
 gradually restore 25OHD above 50 nmol/L over a 2 to 3 month period.

 Given the above rationale there would be no benefit in determining 25OHD values at the
 time of active patient care. For this reason, immediate pre and post-operative blood
 will be collected and stored at -80 oC for batch determination of vitamin D metabolites.

 4.3.2 Elevated urine calcium:creatinine Background - There is a theoretical increased
 risk of hypercalciuria leading to nephrocalcinosis with high dose vitamin D
 supplementation. Although frequently discussed in the literature the association between
 vitamin D supplementation and nephrocalcinosis appears limited to two rare
 circumstances: a rare genetic disorder called vitamin D resistant rickets and cumulative
 vitamin D intake above 600,000 (over a few days or month).

 Pre-treatment urine calcium/creatinine ratios - Given the absence of good evidence
 supporting a link between low to moderate dose daily enteral vitamin D intake and
 hypercalciuria and nephrocalcinosis we have decided not to exclude patients from the
 study based on their pre-treatment urine calcium to creatinine ratio. The pretreatment
 values will be reported in the two treatment groups and will be used to determine
 whether CHD patients with high initial values are more likely to have elevated
 calcium:creatinine ratios at the time of surgery and/or evidence of nephrocalcinosis.
 This finding would result in exclusion of these patients from the subsequent multicenter
 phase III study.

 4.4 Data Safety Monitoring Board (DSMB) A DSMB will be set up for this trial. Study
 results will be analyzed after half of the participants (n=32) have completed all study
 procedures, including assay for 25OHD, ionized calcium and urine calcium:creatinine
 ratios. With the biochemistry and information on clinical adverse events the DSMB will
 determine whether it is safe to continue the pilot study.

 5 - ETHICAL REVIEW AND CONSIDERATIONS The proposed trial has been reviewed by the
 Research Ethics Board at the Children's Hospital of Eastern Ontario. Informed consent
 will be obtained from all parents and from patients (assent, where applicable). All
 participation will be entirely voluntary and parents/children will be informed that they
 are free to refuse to participate or withdraw consent at any time during the course of
 the study without jeopardizing the excellence of the care they receive by the
 cardiovascular surgery program at CHEO. All information will be kept confidential, will
 be accessible only by the study personnel and treating team, and will not be released to
 a third party.

 6 - SAMPLE SIZE DETERMINATION Primary objective - Based on our observational studies and
 findings from recent dose evaluation studies on healthy children we estimate that 40% of
 the usual care arm will have post-operative 25OHD levels above 50 nmol/L. Based on the
 25OHD levels achieved with 1600 IU/day in recent studies on approximate IOM high dose in
 healthy children we anticipate that 80% of the high dose arm will have post-operative
 levels above 50 nmol/L. Therefore group sample sizes of 28 in both treatment arms will
 be required to achieve 80% power to detect a difference between the group proportions of
 0.40. The test statistic used is the two-sided Fisher's exact test and the significance
 level of the test was targeted at 0.05. Assuming a 10% drop out rate, 62 patients
 (total) will be recruited.

 Comments on power for evaluating vitamin D related adverse outcomes - (1) Hypercalcemia
 - Our observational study (n=58) identified no cases of pre-operative or immediate
 post-operative hypercalcemia. With a baseline rate in the usual care arm between 0 and
 10% our sample size would be sufficient to show a statistically significant difference
 between groups if the rate in the high dose arm exceeded 30%. (2) Hypercalciuria -
 Information on baseline rates of hypercalciuria prior to or following cardiac surgery
 with usual care vitamin D intake is not available. The proposed sample size would be
 sufficient to demonstrate a 35% difference in proportions if the baseline pre or
 post-operative rates were between 0 and 20%.

 7 - STATISTICAL ANALYSIS The analyses for both studies will be performed using
 Statistical Analysis System (SAS) software (Copyright SAS Institute Inc., Cary, North
 Carolina, USA) and a p-value less than 0.05 will be considered statistically
 significant.

 Descriptive statistics - Treatment groups will be described and compared using: (i)
 means with standard deviations or medians with inter-quartile range values for
 continuous variables or (ii) frequencies with percentages for categorical variables.
 Statistically significant differences will be determined using Chi-square and Fisher's
 exact tests for categorical variables, and t-tests or nonparametric tests (e.g.
 Wilcoxon) for continuous variables, as appropriate.

 Primary outcome - The primary analytical approach will be to evaluate all randomized
 patients in an intention to treat analysis. Differences in the primary outcome measure,
 proportion with 25OHD < 50 nmol/L, between the treatment groups will be evaluated using
 the Fisher's exact test. Logistic regression analysis will be used if important
 variables are unevenly distributed between groups. *We anticipate minimal missing data
 as over 95% of participants from the recently completed observational study had an
 immediate post-operative sample.

 Secondary outcomes - Secondary analyses will be evaluated between groups based on data
 type. Outcome measures that are continuous will be evaluated using the t-test, Wilcoxon
 sign rank test (where appropriate) or through linear regression analysis if important
 variables are not evenly distributed between groups. Binary secondary outcome measures
 (e.g. hypercalcemia, hypercalciuria) will be compared between the two treatment groups
 using Fisher's exact or Chi-square. For the analysis of outcomes measures that represent
 time to event (e.g. restoration of active hormone (1,25OH2D) levels to normal range,
 time to extubation, PICU length of stay) we will apply the log rank test. If
 randomization does not lead to equal distribution of important variables (e.g. weight)
 the analysis will be expanded to multiple regression modeling.

 Subgroup analysis - The well known pharmacology of enteral vitamin D dosing shows that
 at least 2 months of regular daily intake is required to build body stores and achieve
 steady state blood levels of vitamin D. Consequentially neonates or other infants
 enrolled into the study who require surgery within two months of birth or CHD diagnosis
 will be analyzed separately. Primary objective - Similar to the outpatient study the
 primary objective in this subgroup is to report the proportions (in the usual care and
 high dose groups) that are vitamin D deficient post-operatively. However, given that
 these participants will receive study drug for a very short period we anticipate that
 the proportion with 25OHD levels above 50 nmol/L will remain low in the high dose group.
 Our program goal at this stage is to identify a dosing regimen that prevent
 post-operative vitamin D deficiency in 75% of CHD patients. Given this goal, and an
 estimated prevalence of 15 to 35% we would need 12 neonates per group to generate a
 confidence interval that excludes 75%. As neonates represent 20% of all CHD surgeries,
 we anticipate that enrolling 62 total subjects will be sufficient.

 Feasibility - Most neonates with CHD who require cardiac surgery within the first few
 weeks of life have serious cardiac lesions that can limit enteral nutrition and
 medication delivery. Anticipating that most of these patients will not significantly
 elevate 25OHD levels with daily enteral intake at IOM high dose this study will provide
 important information on the willingness of health care providers to provide enteral
 study drug. This information will allow us to consider alternative dosing regimen for
 future studies based on single or divided representing one or more months worth of daily
 dosing (e.g. 5-10,000 IU/kg).

 8 - STUDY TEAM AND MANAGEMENT The principal investigator (DM) and co-investigator (KM)
 will be responsible for supervision of the study. The research nurse and assistant(s)
 will be responsible for participant recruitment and day-to-day management. The Clinical
 Research Unit at the CHEO Research Institute which will provide administrative and data
 management support. Co-investigator, Dean Fergusson will assist with methodology,
 analysis, and interpretation
Inclusion Criteria:

 -  Newborn (corrected gestational age between 36 weeks) up to 18 years

 -  Has CHD that will require surgery within the next 12 months

 -  CHD requiring surgical intervention with cardiopulmonary bypass

 Exclusion Criteria:

 -  Born at less than 32 weeks gestational age

 -  Corrected gestational age of less than 36 weeks

 -  Cardiac or gastrointestinal disease preventing enteral feeds or drug administration
 prior to surgery

 -  Patient has confirmed or suspected Williams syndrome

 -  Proposed surgery to take place at another centre (outside of CHEO)