Arpadi SM, McMahon D, Abrams EJ, Bamji M, Purswani M, Engelson ES, Horlick M, Shane E Effect of bimonthly supplementation with oral cholecalciferol on serum 25-hydroxyvitamin D concentrations in HIV-infected children and adolescents. Pediatrics. 2009 Jan;123(1):e121-6. doi: 10.1542/peds.2008-0176. Erratum in: Pediatrics. 2009 May;123(5):1437.
Bischoff-Ferrari HA "Vitamin D - why does it matter?" - defining vitamin D deficiency and its prevalence. Scand J Clin Lab Invest Suppl. 2012;243:3-6. doi: 10.3109/00365513.2012.681938.
Fazekas de St Groth B, Landay AL Regulatory T cells in HIV infection: pathogenic or protective participants in the immune response? AIDS. 2008 Mar 30;22(6):671-83. doi: 10.1097/QAD.0b013e3282f466da. Review.
Haug C, Müller F, Aukrust P, Frøland SS Subnormal serum concentration of 1,25-vitamin D in human immunodeficiency virus infection: correlation with degree of immune deficiency and survival. J Infect Dis. 1994 Apr;169(4):889-93.
Haug CJ, Aukrust P, Haug E, Mørkrid L, Müller F, Frøland SS Severe deficiency of 1,25-dihydroxyvitamin D3 in human immunodeficiency virus infection: association with immunological hyperactivity and only minor changes in calcium homeostasis. J Clin Endocrinol Metab. 1998 Nov;83(11):3832-8.
Rabe-Hesketh S, Skrondal A Multilevel and longitudinal modeling using Stata. Volume 1: Continuous responses. College Station, TX: Stata Press; 2012.
Rodríguez M, Daniels B, Gunawardene S, Robbins GK High frequency of vitamin D deficiency in ambulatory HIV-Positive patients. AIDS Res Hum Retroviruses. 2009 Jan;25(1):9-14. doi: 10.1089/aid.2008.0183.
Rutstein R, Downes A, Zemel B, Schall J, Stallings V Vitamin D status in children and young adults with perinatally acquired HIV infection. Clin Nutr. 2011 Oct;30(5):624-8. doi: 10.1016/j.clnu.2011.02.005. Epub 2011 Jun 8.
Ryan P Random allocation of treatments in blocks. Stata Journal;8:594, 2008
Shearer GM, Clerici M Cytokine profiles in HIV type 1 disease and protection. AIDS Res Hum Retroviruses. 1998 Jun;14 Suppl 2:S149-52. Review.
Sloka S, Silva C, Wang J, Yong VW Predominance of Th2 polarization by vitamin D through a STAT6-dependent mechanism. J Neuroinflammation. 2011 May 24;8:56. doi: 10.1186/1742-2094-8-56.
Veldman CM, Cantorna MT, DeLuca HF Expression of 1,25-dihydroxyvitamin D(3) receptor in the immune system. Arch Biochem Biophys. 2000 Feb 15;374(2):334-8.
Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease.
Observational studies are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods.
Expanded access is a means by which manufacturers make investigational new drugs available, under certain circumstances, to treat a patient(s) with a serious disease or condition who cannot participate in a controlled clinical trial.
Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.
Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.