Gao H, Liu Z, Xing D, Gong M Which is the best alternative for displaced femoral neck fractures in the elderly?: A meta-analysis. Clin Orthop Relat Res. 2012 Jun;470(6):1782-91. doi: 10.1007/s11999-012-2250-6. Epub 2012 Jan 26.
Petersen MK, Andersen KV, Andersen NT, Søballe K "To whom do the results of this trial apply?" External validity of a randomized controlled trial involving 130 patients scheduled for primary total hip replacement. Acta Orthop. 2007 Feb;78(1):12-8.
Pibouleau L, Boutron I, Reeves BC, Nizard R, Ravaud P Applicability and generalisability of published results of randomised controlled trials and non-randomised studies evaluating four orthopaedic procedures: methodological systematic review. BMJ. 2009 Nov 17;339:b4538. doi: 10.1136/bmj.b4538. Review.
Rothwell PM External validity of randomised controlled trials: "to whom do the results of this trial apply?". Lancet. 2005 Jan 1-7;365(9453):82-93.
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.
