Kessler R, Faller M, Fourgaut G, Mennecier B, Weitzenblum E Predictive factors of hospitalization for acute exacerbation in a series of 64 patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med. 1999 Jan;159(1):158-64.
McKenna SP, Doughty N, Meads DM, Doward LC, Pepke-Zaba J The Cambridge Pulmonary Hypertension Outcome Review (CAMPHOR): a measure of health-related quality of life and quality of life for patients with pulmonary hypertension. Qual Life Res. 2006 Feb;15(1):103-15.
McKenna SP, Ratcliffe J, Meads DM, Brazier JE Development and validation of a preference based measure derived from the Cambridge Pulmonary Hypertension Outcome Review (CAMPHOR) for use in cost utility analyses. Health Qual Life Outcomes. 2008 Aug 21;6:65. doi: 10.1186/1477-7525-6-65.
Rubenfire M, Lippo G, Bodini BD, Blasi F, Allegra L, Bossone E Evaluating health-related quality of life, work ability, and disability in pulmonary arterial hypertension: an unmet need. Chest. 2009 Aug;136(2):597-603. doi: 10.1378/chest.08-1260. 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.
