Beyond randomized controlled trials: A critical comparison... : Hepatology (original) (raw)
Perspectives in Clinical Hepatology
Beyond randomized controlled trials: A critical comparison of trials with nonrandomized studies
1_Department of Clinical Epidemiology, Aarhus University Hospital, 8000 Aarhus C, Denmark_
2_Department of Epidemiology, Boston University School of Public Health, Boston, MA_
*Department of Clinical Epidemiology, Aarhus University Hospital, Ole Worms Allé 1150, DK-8000 Aarhus C, Denmark
Email:[email protected]
Received 7 June 2006; Accepted 8 September 2006
Published online in Wiley InterScience (www.interscience.wiley.com).
Grant sponsor: Danish Research Agency; Grant Number: 271-05-0511; Grant sponsor: Ingeborg and Leo Dannins Foundation for Scientific Research.
Potential conflict of interest: Nothing to report.
fax (45) 89 42 48 01.
Abstract
Observational analogs of randomized clinical trials (RCTs) are well accepted in the study of disease risk factors, diagnosis, and prognosis. There is controversy about observational studies when the focus is on the intended benefit due to lack of blinding and poor control for unmeasured confounding. Well-designed randomized clinical trials are costly both in time and money. Therefore, existing databases are used increasingly and are often the only feasible source with which to examine delayed health effects. We reviewed the reasons for possible discrepancies between RCTs and observational studies. There can be different patient populations, differences in therapeutic regimen, control of confounding, follow-up, measuring outcome, and differences arising from the intention-to-treat analysis. Observational studies cannot replace trials, nor do trials make observational studies unnecessary. Both designs are susceptible to particular bias, so neither provides perfect information.
Copyright © 2006 American Association for the Study of Liver Diseases.