U.S. National Library of Medicine

Introduction to Health Services Research : A Self-Study Course

Module 5: Quality Filtering and Evidence-Based Medicine and Health (page 5 of 15)

Introduction to Quality Filtering and Evidence-Based Medicine and Health

Quality Filtering

Not all studies are created equal. Not all articles are equally good. An important role for the health sciences librarian is quality filtering. Quality filtering is a process that sifts the more substantial studies from the less informative ones.

Librarians perform quality filtering when they search and choose articles that best answer the information needs of the requester. In clinical settings, the criteria that guide selection are the individual patient's characteristics.

Librarians perform quality filtering when they search and choose articles that best answer the information needs of the requester.

Clinical librarians perform this valuable service as part of the health care team that conducts patient rounds, resident reports, or tumor conferences.

In health services research, the questions deal with larger populations than in the clinical setting. Researchers need to know the impact of mammography on breast cancer mortality or the effectiveness of one thrombolytic therapy compared to another. To answer these questions, they must analyze large amounts of data that represent large groups of people. In this setting as well as the clinical one, the selection of literature is critical.

Need for Quality Filtering

Therefore, the need for quality filtering has increased as health researchers and policy makers produce clinical guidelines or conduct meta-analyses. Clinical guidelines recommend a particular protocol for prevention or treatment. Their authors synthesize large amounts of literature to discover the evidence for best practices. Many of them carefully rank the evidence based on the study design used to achieve the results.

Gold Standard Studies

In general, randomized clinical trials are considered the best or the "gold standard", rated above other study designs and expert opinions. However, it is not often feasible or ethical to conduct randomized clinical trials. (You could never randomize people into smoking or non-smoking groups to determine the risk of lung cancer!) In these situations, other evidence is used to make decisions.

Meta-analysis

Meta-analysis is a statistical technique that combines data from similar studies to maximize the data from smaller, individual studies. Researchers carefully stipulate what studies "qualify" for analysis.

This reliance on the published literature for clinical and policy decision-making is called "evidence-based medicine" and "evidence-based health."

Practitioners of evidence-based medicine systematically collect and analyze the best studies before combining them and drawing conclusions. They champion this approach as the most objective way to set standards for medical practice or health policy.

Practitioners of evidence-based medicine systematically collect and analyze the best studies before combining them and drawing conclusions. They champion this approach as the most objective way to set standards for medical practice or health policy.

Evidence-based medicine adds data to personal experiences and decreases reliance on expert opinion or custom. The search for evidence also reveals the gaps in the published literature, indicating the need for particular research studies.

Critics of evidence-based medicine charge that this approach is too confining since the "pure" conditions under which clinical trials occur cannot be replicated in the "real world."

Medical Students Learn Evidence-based Medicine

Traditionally, medical schools teach students to untangle clinical options based on the pathophysiology of the disease, clinical experience, textbook information, and expert opinion. The new approach requires competent literature searching and critical appraisal skills that entail knowledge of study design and epidemiology. Other detractors of evidence-based medicine question whether EBM offers anything new (Evidence-based medicine working group, 1992).

Issues with Evidence-based Medicine

It is important to be aware of the controversies of evidence-based medicine, clinical practice guidelines, and meta-analysis. Nonetheless, the emphasis on evidence-based medicine provides health sciences librarians with new avenues for collaboration and opportunities to learn study design and statistics.

There are a number of different types of studies used in health services research. The following section provides an overview of the basic designs as well as their corresponding strengths and weaknesses. See if you can apply these concepts to a literature retrieval search you do during the course.

Discussion Questions

1. In the past evidence-based medicine (EBM) was a contentious issue. Is it now? Discuss how EBM is being used in your organization and the effect is has had on the provision of health care.
2. What is the librarian's role in research projects with respect to searching for quality clinical information? Has it changed since 1970?
3. When librarians are not involved in the search for quality articles, things can go wrong in a research project. Discuss how the death of an individual in a research project at two different universities could have been avoided by involving a librarian in quality filtering.
4. Have guidelines been set up for librarians to assist them in their search for research content during the quality filtering process? Discuss.
5. Evidence-based public health (EBPH) is also important to librarians providing services to health services researchers since there is often cross-over research. Do you know the difference between EBPH and EBM? (hint: examine the online chapter on EBPH in the Public Health Manual).