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Pulm Pharmacol Ther. 2014 Apr;27(2):129-38. doi: 10.1016/j.pupt.2014.01.005. Epub 2014 Jan 24.

Randomized Controlled Trials and real life studies. Approaches and methodologies: a clinical point of view.

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Respiratory Medicine, Department of Medical Sciences, University of Ferrara, Ferrara, Italy.
Allergy and Respiratory Diseases Clinic, DIMI, University of Genoa, IRCS AOU San Martino-IST, Genoa, Italy.
Cardio-Thoracic and Vascular Department, University Hospital of Pisa, Italy.
Section of Respiratory Diseases, Department of Surgery and Clinical Medicine, University of Naples, Italy.
Department of Internal Medicine, Section of Pulmonology (DIBIMIS), University of Palermo, Italy.
Dipartimento di Scienze della Salute, Pneumologia Riabilitativa, Fondazione Salvatore Maugeri, Istituto Scientifico di Milano IRCCS, University of Milan, Milan, Italy.
Respiratory Medicine, Department of Medical Sciences, University of Ferrara, Ferrara, Italy. Electronic address:


Randomized Controlled Trials (RCTs) are the "gold standard" for evaluating treatment outcomes providing information on treatments "efficacy". They are designed to test a therapeutic hypothesis under optimal setting in the absence of confounding factors. For this reason they have high internal validity. The strict and controlled conditions in which they are conducted, leads to low generalizability because they are performed in conditions very different from real life usual care. Conversely, real life studies inform on the "effectiveness" of a treatment, that is, the measure of the extent to which an intervention does what is intended to do in routine circumstances. At variance to RCTs, real life trials have high generalizability, but low internal validity. Recently the number of real life studies has been rapidly growing in different areas of respiratory medicine, particularly in asthma and COPD. The role of such studies is becoming a hot topic in respiratory medicine, attracting research interest and debate. In the first part of this review we discuss some of the advantages and disadvantages of different types of RCTs and analyze the strengths and weaknesses of real life trials, considering the recent examples of some studies conducted in COPD. We then discuss methodological approaches and options to overcome some of the limitations of real life studies. Comparing the conclusions of effectiveness and efficacy trials can provide important pieces of information. Indeed, these approaches can result complementary, and they can guide the interpretation of each other results.


Asthma; COPD; Randomized controlled trials; Real life studies

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