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Washington State contracts with the Center for Evidence-Based Policy (Oregon EPC), Oregon Health and Science University to independently review prescription drugs comparing the safety, efficacy, and effectiveness of drug classes and providing updates every six months. As a part of the review process, health care specialists will be asked to provide feedback to help ensure that the concerns of patients and practitioners are thoroughly considered. This dialogue will identify the populations to be addressed, interventions to be studied, and the health and other outcomes (both positive and negative) to be evaluated. When completed, key questions will be developed to guide the reviews, specifying the clinical conditions (diagnoses, disease) of interest for the particular review; defining the populations, interventions, and outcomes (expected benefits, potential risks or harms); and distinguishing intermediate outcomes (e.g. laboratory test results or biometric measures) from true health outcomes (e.g. death, morbidity, functioning, quality of life); and focusing the research on true health outcomes when possible.
Finding Evidence
The Oregon Evidence-Based Practice Center uses several search techniques to gather clinical evidence included in the reviews. These techniques include searching major databases of the world's medical literature and other resources such as systematic reviews found in the Cochrane Collaboration Library. In addition the Center can accept published or unpublished information from all reasonable sources as long as it can be publicly compared with information acquired by more traditional methods.
Selecting the Evidence
When considering the types of research that will be accepted, although randomized controlled trials (RCT's) involving head-to-head comparisons of drugs may be the optimal design for this process, they are not the only evidence that may be valuable to or necessary for decision makers. RCT's with placebo controls, for example, may be important as well. Moreover, large, well designed studies other than RCT's are often critical sources of data on populations not typically included in RCT's, on longer-term outcomes, and on potential adverse events.
Once the eligibility criteria is identified, the process of searching for relevant evidence begins by reviewing entire articles or titles and abstracts of research studies against the eligibility criteria and deciding which items to use and which to set aside. If an article or study is excluded from consideration, the reason for doing so is recorded as part of the final documentation.
After the acceptable information sources have been identified, the information is placed into detailed evidence tables that provide crucial information on study purpose and design, populations, diagnoses or conditions, interventions, outcomes, and other data. The institute will coordinate communications between the researchers and the participating organizations to make certain that the eligibility criteria and the evidence tables meet the needs of the participating organizations.
Establishing and Presenting the Evidence
Establishing evidence is the process of analyzing and combining all good information from the review of research studies and findings relevant to the key questions. Analysts typically rely heavily on information from evidence tables for this task. This step, and the overall presentation of evidence, can be done in qualitative terms, through text discussion of the evidence, and through statistical combination of information in a technique known as meta-analysis.
A critical element of the evaluation of the evidence involves two related steps:
- Grading the quality of individual studies and
- Rating the strength of the overall body of evidence.
These are formal steps for which well-recognized methods exist. For a systematic review to be defensible it is imperative that both of these judgments be made in a clear and consistent manner. Review of the quality of individual studies relies on study design and conduct. Study design alone is not sufficient. The best-designed study can provide poor evidence if the conduct of the study does not rigorously follow good research practice. The quality of a study is often summarized as providing good, fair, or poor evidence, and reviewers must clearly state how the review uses each category of evidence. For example, does the review consider (but down-weigh) poorly designed or conducted studies or exclude them altogether?. This may be particularly important when quantitative syntheses are performed. Another consideration is that study quality may not, by itself, be sufficient. A very good study that has only limited applicability to a key question may not be as helpful as a fair study that is directly related to the key question.
Often, systematic reviews will focus particular attention on a limited number of high-quality, critical studies from which key evidence can be highlighted in more detail. Evidence tables are always created to allow those decision makers who wish to do so the opportunity to examine the entirety of the evidence. For ease of presentation, summary tables derived from detailed evidence tables may also be desirable. Equally desirable approaches to presenting information about the magnitude of benefits and harms such as balance sheets that provide results in terms of the number of patients who would benefit or be harmed by undergoing a particular intervention can be used. The Center will work with the participating organizations and researchers to make certain the information reviewed is arrayed in ways that are most useful to the policy makers who will use it.
As all the evidence is organized into evidence tables, summary tables, and text, reviewers then need to make some assessment of the overall quality and applicability of the evidence. The questions at this stage involve the cumulative quality of the studies (are studies mostly of good quality, mostly of fair or only poor quality, or a mix), the quantity of the data ( e.g., numbers of studies and aggregate sample sizes), and consistency (e.g., do the studies show consistent results or are some clearly negative and some positive). Again, the entire body of evidence is often characterized as good, fair, or poor, and typically the limitations of the literature are discussed.
Conducting Peer Reviews
Peer reviewers are asked to comment on factual matters, presentation, interpretation, missing information, readability/usability, and similar matters. The aim is to identify omissions, unwarranted conclusions or inferences, unintentional bias, inadvertent over- or under-emphasis, and unnecessarily tedious, obscure, or misleading writing.
Peer review is an integral part of the standards required by the Agency for Healthcare Research and Quality (AHRQ) for developing systematic reviews. Comments from reviewers are all given serious consideration.
Preparing the Final Review
During or following the peer review, the authors of the systematic review begin necessary revisions. All legitimate points raised by the peer review are addressed in the final draft of the systematic review. For example, if reviewers note important missing data or studies, these are obtained and data from them are added to evidence tables and text, as appropriate.
Once the authors have completed the final evidence report, they will then make it available for distribution as determined by the participating organizations. The authors of the report may also submit the report, or a summary, for publication in a scientific journal. These journals further enhance the credibility and impact of the reports and of the evidence-based process within the scientific community.
Evidence Based Practice Centers
In 1997, the AHRQ began promoting evidence-based practice in everyday health care through establishment of 13 Evidence-Based Practice Centers (EPC's). The EPC's develop evidence reports and technology assessments on clinical conditions or health services that are common, expensive, and/or are significant for the Medicare and Medicaid populations. With this program, AHRQ became the lead federal agency and a science partner with private and public organizations in their efforts to improve the quality, effectiveness, and appropriateness of health care by assisting the translation of evidence-based research findings into clinical practice.
AHRQ conducts and funds research that develops and presents evidence-based information on health care outcomes, quality, cost, use, and access. Included in AHRQ's legislative mandate is support for the establishment and distribution of scientific evidence. The research results assist practitioners, clinicians, patients, and policymakers in making evidence based decisions regarding the quality and effectiveness of health care.
More than 100 reviews and analyses of scientific literature have been conducted and used by care systems, organizations, health plans, public and private purchasers, states, and other entities as a foundation for developing and implementing their own clinical practice guidelines, clinical pathways, review criteria, performance measures, and other clinical quality improvement tools, as well as for formulating evidence-based policies related to specific health care technologies. Summaries of EPC reports may be reviewed by visiting AHRQ's web site.
