Cross Design Synthesis:

A New Strategy for Medical Effectiveness Research

PEMD-92-18: Published: Mar 17, 1992. Publicly Released: Mar 17, 1992.

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Pursuant to a congressional request, GAO reviewed medical study designs, focusing on: (1) the medical effectiveness of existing designs; and (2) evaluation strategies that avoid the limitations of existing approaches.

GAO found that: (1) randomized studies and data-base analyses are complementary medical study designs; (2) randomized studies are designed to achieve a valid comparison of alternative treatments, but results may not be fully generalizable to the varied conditions of medical practice; (3) to minimize the risk of overstating a treatment's average effect in the patient population, results of existing randomized studies should be subject to an in-depth assessment of their generalizability; (4) data-base analyses are potentially weak because patients are not randomly assigned to alternative treatments; and (5) multiple assessments of comparison bias can minimize imbalances in data-base analyses and indicate and enhance the usefulness of data-base results. GAO noted that: (1) it devised a strategy that extends the logic of meta-analysis or quantitative overview, which specifies ways of combining results from similar studies; and (2) the new strategy, cross design synthesis, combines results from studies complementary designs in order to capture the designs' strengths and minimize the studies' weaknesses.