Cohen H, Chen XC, Sunkle S, Davis L, Geromanos K, Xanthos G, Shearer W Ability of caregivers to read delayed hypersensitivity skin tests in children exposed to and infected by HIV. The Pediatric Pulmonary and Cardiovascular Complications of Vertically Transmitted HIV Study Group. J Pediatr Health Care. 2000 Mar-Apr;14(2):50-5.
Demmler GJ, Istas A, Easley KA, Kovacs A Results of a quality assurance program for detection of cytomegalovirus infection in the pediatric pulmonary and cardiovascular complications of vertically transmitted human immunodeficiency virus infection study. J Clin Microbiol. 2000 Nov;38(11):3942-5.
Shearer WT, Rosenblatt HM, Schluchter MD, Mofenson LM, Denny TN Immunologic targets of HIV infection: T cells. NICHD IVIG Clinical Trial Group, and the NHLBI P2C2 Pediatric Pulmonary and Cardiac Complications of HIV Infection Study Group. Ann N Y Acad Sci. 1993 Oct 29;693:35-51. Review.
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.