Randomized phase 2 trial of monthly vitamin D to prevent respiratory complications in children with sickle cell disease.

In sickle cell disease, respiratory infection and asthma may lead to respiratory complications that are a leading cause of morbidity and mortality. Vitamin D has anti-infective and immunomodulatory effects that may decrease the risk for respiratory infections, asthma, and acute chest syndrome. We conducted a randomized double-blind active-controlled clinical trial to determine whether monthly oral vitamin D can reduce the rate of respiratory events in children with sickle cell disease. Seventy sickle cell subjects, ages 3-20 years, with baseline records of respiratory events over 1 year before randomization, underwent screening. Sixty-two subjects with 25-hydroxyvitamin D levels of 5-60 ng/mL were randomly assigned to oral vitamin D (100 000 IU or 12 000 IU, n = 31 each) under observed administration once monthly for 2 years. The primary outcome was the annual rate of respiratory events (respiratory infection, asthma exacerbation, or acute chest syndrome) ascertained by the use of a validated questionnaire administered biweekly. Analysis included 62 children (mean age of 9.9 years, 52% female, and predominantly with homozygous HbS disease [87%]) with mean baseline 25-hydroxyvitamin D of 14.3 ng/mL. The annual rates of respiratory events at baseline and intervention years 1 and 2 were 4.34 ± 0.35, 4.28 ± 0.36, and 1.49 ± 0.37 (high dose) and 3.91 ± 0.35, 3.34 ± 0.37, and 1.54 ± 0.37 (standard dose), respectively. In pediatric patients with sickle cell disease, 2-year monthly oral vitamin D was associated with a >50% reduction in the rate of respiratory illness during the second year ( = .0005), with similar decreases associated with high- and standard-dose treatment. This trial was registered at www.clinicaltrials.gov as #NCT01443728.