Daily Vitamin D for Sickle-cell Respiratory Complications (ViDAS-2)

  • End date
    Feb 28, 2025
  • participants needed
  • sponsor
    Gary M Brittenham, MD
Updated on 15 July 2022
vitamin d
vitamin d supplementation
hemoglobin s
sickle cell disease
sickle cell anemia
hb s
sickle hemoglobin
hb ss


This study aims to answer the question whether daily oral vitamin D supplementation can reduce the risk of respiratory or lung complications in children and adolescents with sickle cell disease. Respiratory problems are the leading causes of sickness and of death in sickle cell disease. The investigators hypothesize that daily oral vitamin D3, compared to monthly oral vitamin D, will rapidly increase circulating vitamin D3, and reduce the rate of respiratory complications by 50% or more within the first year of supplementation in children and adolescents with sickle cell disease.

This study is funded by the FDA Office of Orphan Products Development (OOPD).


This is a 2-year controlled, double-blind, randomized Phase 2 clinical trial comparing the efficacy in reducing the rate of respiratory events in sickle-cell disease of daily oral vitamin D3 (3,333 IU/d) with monthly bolus oral vitamin D3, (100,000 IU/mo) as a control. The scientific premise of the clinical trial is that circulating concentrations of vitamin D3, the parent compound, are the principal determinant of the anti-infective and immunomodulatory effects of supplementation.

Eligible participants will be initially screened to determine their blood vitamin D levels. Those with 25-hydroxyvitamin D levels between 5 and 60 ng/mL will be assigned by chance to one of the two arms for 24 months. Participants will be checked every month and will have periodic blood and urine tests to monitor for any side effects of the study treatments. Children above 5 y/o who can cooperate and understand the procedure will have lung function test at baseline and at 24 months. Showing that a monthly dose of vitamin D reduces lung infections, asthma and the acute chest syndrome could help establish this simple, low-cost treatment as a way to decrease sickness and deaths in children and adolescents with sickle-cell disease.

Condition Sickle Cell Disease, Anemia, Sickle Cell, Anemia, Hemolytic, Congenital, Respiratory Tract Diseases, Respiration Disorders, Acute Chest Syndrome, Lung Diseases, Asthma, Respiratory Tract Infections, Nutrition Disorders, Deficiency Diseases Vitamin, Vitamin D Deficiency
Treatment Placebo Oral Tablet, Daily oral vitamin D3, 3,333 IU, Bolus oral vitamin D3, 100,000 IU
Clinical Study IdentifierNCT04170348
SponsorGary M Brittenham, MD
Last Modified on15 July 2022


Yes No Not Sure

Inclusion Criteria

Diagnosis of sickle cell disease (Hb SS, Hb SC, Hb S-Beta-thalassemia)
Age 3-20 years old

Exclusion Criteria

Patient unwilling or unable to provide written informed consent (and assent, if applicable)
Patient unable or unwilling to comply with requirements of the clinical trial
Participation in another clinical trial
Current diagnosis of rickets
History of hypercalcemia or diagnosis of any medical condition associated with hypercalcemia, including primary hyperparathyroidism, malignancy, sarcoidosis, tuberculosis, granulomatous disease, familial hypocalciuric hypercalcemia
Current use of corticosteroids, excluding inhaled steroids
Current use of anticonvulsants (phenytoin, phenobarbital, carbamazepine)
Therapy with thiazide diuretics or lithium carbonate
Known liver or renal disease
Patients taking medications for pulmonary complications of sickle cell disease not on a stable dose of medications, as defined by a change in medications or doses within the three months prior to study entry
Patients on chronic red blood cell transfusion therapy
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