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New Report Examines Systems That Rate the Strength of Scientific Research Studies and Their Findings

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Press Release Date: May 6, 2002

A new report sponsored by the Agency for Healthcare Research and Quality (AHRQ) identifies and compares systems that rate the quality of evidence in individual research studies and compilations of studies addressing a common scientific issue. The report also provides guidance on the leading approaches currently in use for improving the quality of scientific evidence.

In 1999, Congress mandated AHRQ to identify and disseminate "methods or systems to rate the strength of the scientific evidence underlying health care practice, recommendations in the research literature, and technology assessments." To address this charge from Congress, AHRQ commissioned its Evidence-based Practice Center (EPC) at RTI International-University of North Carolina to review these methods and systems and produce a report on their methods and findings, entitled Systems to Rate the Strength of Scientific Evidence.

"This report will be invaluable to researchers and policymakers in evaluating the quality and strength of scientific evidence in an ever-growing sea of research," said AHRQ Acting Director Carolyn Clancy, M.D. "Researchers also will be able to use this information in future research design, to better ensure the quality of their work."

In its review, the EPC identified 121 sources that deal with systems that rate the quality of individual studies-systematic reviews, randomized clinical trials, observational studies, and studies of diagnostic tests-or that grade the strength of bodies of evidence, including 12 reports from AHRQ-supported EPCs. The EPC then evaluated the systems that rate the quality of individual studies using criteria based on findings from previous studies and best practices from clinical research for each of the four study designs. It also evaluated the systems for grading the bodies of evidence using three criteria—quality, quantity and consistency.

Using well-specified criteria, the researchers identified 19 study-quality and 7 strength-of-evidence grading systems that people conducting systematic reviews and technology assessment can use as starting points for future evidence-based research projects.

The full report, Systems to Rate the Strength of Scientific Evidence, is available by calling the AHRQ Publications Clearinghouse at 1-800-358-9295 or sending an E-mail to The summary is available online or through the AHRQ Publications Clearinghouse. A fact sheet, entitled Rating the Strength of Scientific Research Findings, also is available online or through the AHRQ Publications Clearinghouse.

For additional information, please contact AHRQ Public Affairs, (301) 427-1364.


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