NCT04170348.

Study name	Daily Vitamin D for Sickle‐cell Respiratory Complications (ViDAS‐2)
Methods	Study design: double‐blind parallel RCT Study duration: 2 years Location: USA
Participants	Inclusion criteria sickle cell disease (Hb SS, Hb SC, Hb S‐Beta‐thalassemia) and aged 3 ‐ 20 years old Exclusion criteria unwilling to provide written informed consent participation in another clinical trial current diagnosis of rickets history of hypercalcaemia or diagnosis of any medical condition associated with hypercalcaemia, including primary hyperparathyroidism, malignancy, sarcoidosis, tuberculosis, granulomatous disease, familial hypocalciuric hypercalcaemia current use of corticosteroids (excluding inhaled steroids), anticonvulsants (phenytoin, phenobarbital, carbamazepine), 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
Interventions	Intervention: oral vitamin D3, 3,333 IU/day Control: bolus oral vitamin D3, 100,000 IU/month
Outcomes	Primary outcome annual rate of respiratory events (calculated as sum of respiratory infections, asthma exacerbations, or acute chest syndrome) (measured using validated questionnaire) Secondary outcome Change from baseline up to 24 months in: FVC % predicted FEV1 % predicted) FEV1 % predicted/FVC % predicted FEF25-75 % predicted % of the ratio of RV to TLC DLCO % predicted FENO in parts per billion MIP cm H2O MEP cm H2O serum interleukin 2 concentration (IL 2) pg/mL serum interleukin 4 concentration (IL 4) pg/mL serum interleukin 5 concentration (IL 5) pg/mL serum interleukin 13 concentration (IL 13) pg/mL serum interferon gamma concentration (IFN gamma) pg/mL serum interleukin 10 concentration (Iinterleukin 10) pg/mL serum transforming growth factor beta (TGF beta) pg/mL blood Hb concentration g/dL blood platelet concentration platelets/mL serum C‐reactive protein mg/L serum interleukin 1alpha pg/mL serum interleukin 1beta pg/mL serum TNF alpha pg/mL serum C‐terminal telopeptides of Type I collagen ng/mL serum intact N‐terminal propeptide of type I procollagen µg/L
Starting date	February 2020
Contact information	(1) Gary M Brittenham, MD (gmb31@cumc.columbia.edu) (2) Margaret T Lee, MD (ml653@cumc.columbia.edu)
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