This discussion would be strengthened by recognizing that therapy and prevention pose very different questions: The more serious an illness is, the greater the likelihood that a therapy supported only by observational studies will make the patient better. In the case of an asymptomatic person without illness the evidence for a preventive intervention must be much stronger (that is, RCT level) for there to be the same likelihood that the person will be made better by the intervention. Jim James M. Walker, MD, FACP Chief Medical Information Officer Geisinger Health System >>> Mike/Linda Stuart <[log in to unmask]> 08/25/06 5:41 PM >>> I've noticed that several list members have advocated the use of observational studies if they are the "best available" evidence. For interventions dealing with therapy, prevention or screening it has been well-established that even well-done observational studies can provide completely misleading results. For example, the observational studies done on HRT were correct in that there was an association between HRT use and secondary prevention of cardiac events, but it was false that it was a cause-effect relationship (it was confounded by the healthy-user effect). The following reading might be helpful to those who would like further evidence as to why observational studies can mislead in addressing these kinds of clinical questions. At the following link, chose the title, "The Problems with the Use of Observational Studies to Draw Cause and Effect Conclusions About Interventions [PDF] " -- Michael Stuart MD President, Delfini Group, Clinical Asst Professor, UW School of Medicine 6831 31st Ave N.E. Seattle, Washington 98115 206-854-3680 Mobile Phone 206-527-6146 Home Office [log in to unmask] www.delfini.org -----Original Message----- From: Evidence based health (EBH) [mailto:[log in to unmask]] On Behalf Of brnbaum Sent: Friday, August 25, 2006 6:22 AM To: [log in to unmask] Subject: Re: Deconstructing the evidence-based discourse in healthsciences) From my perspective as a hospital epidemiologist, the important division of perspective here certainly isn't simply quantitative vs. qualitative and nursing vs. medicine. Infection control, for example, cuts across all these disciplines and much of the evidence behind infection control is based on knowledge gleaned from observational study designs in areas where RCT's aren't ethical, feasible or both. Much in healthcare administration and management has been rooted in tradition and assumption, dealing with fundamental questions where a mix of quantitative and qualitative research would better guide decisions. Many decisions in medicine need to be informed about effectiveness as well as efficacy... We certainly need to advance our knowledge by critical appraisal and grading of research evidence. When information needs relate to questions of efficacy, then RCT's are the best form of evidence. When questions relate to effectiveness, then observational studies like cohort & case-referent studies probably are best. When questions relate to efficiency or cost-effectiveness or perceived utility, yet other research paradigms are better tools. That being said, I believe educational deficits are part of the root cause for the chasm between these various camps. Poor numeracy skills hamper many of the students, entering nursing and other disciplines, that I've seen over the years. Inadequate emphasis on interdisciplinary education reinforces many of the silo mentalities I've encountered throughout health care organizations. Simplistic audit approaches reinforced by well-intentioned but short-sighted accreditation mandates have kept the position qualifications and program expectations too low in hospitals' safety, infection control, quality improvement and other such programs. There have been a number of interesting articles published in CLINICAL GOVERNANCE related to these points, including one with a nice flowchart to help distinguish audit from quality improvement from research per se - a spectrum of activity we should be seeing within every healthcare organization (not a spectrum dividing hospital-based health professional activity from university-based researcher activity). This has been an interesting thread. Let's bring our focus back to a convergence of useful tools! -- David Birnbaum, PhD, MPH Adjunct Professor School of Nursing University of British Columbia Principal, Applied Epidemiology British Columbia, Canada IMPORTANT WARNING: The information in this message (and the documents attached to it, if any) is confidential and may be legally privileged. It is intended solely for the addressee. Access to this message by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution or any action taken, or omitted to be taken, in reliance on it is prohibited and may be unlawful. If you have received this message in error, please delete all electronic copies of this message (and the documents attached to it, if any), destroy any hard copies you may have created and notify me immediately by replying to this email. Thank you.