Insufficient evidence regarding the effectiveness of medical treatments has been identified as a key source of inefficiency in the U.S. healthcare system. Clinicians vary widely in their recommendation and use of diagnostic tests and treatments for patients with similar symptoms or conditions. This variation has been attributed to clinical uncertainty, since the current published scientific evidence base does not provide adequate information to determine which treatments are most effective for patients with specific clinical needs. A surprisingly high proportion of the healthcare services received by patients today may have limited value, while some care may even be harmful (Owens, Qaseem, et al., 2011). By helping clinicians, patients, payers, and others to better distinguish between effective and ineffective (or potentially harmful) therapies, comparative effectiveness research (CER) has the potential to slow the growth of spending on healthcare without adversely affecting the quality of care.
The Institute of Medicine (IOM) defines CER as the generation and synthesis of evidence that compares the benefits and harms of alternative methods for preventing, diagnosing, treating, and monitoring a clinical condition or improving the delivery of care. It further states that the purpose of CER is to assist consumers, clinicians, purchasers, and policymakers in making informed decisions that will improve healthcare at both the individual and population levels. The Federal Coordinating Council for Comparative Effectiveness Research used similar terms to define CER (Federal Coordinating Council for Comparative Effectiveness Research, 2009).[*]
CER differs from other clinical research in a number of key ways. First, it is intended to provide information directly relevant to the decisions of a wide range of stakeholders, since it addresses both the clinical and policy aspects in the selection of tests, treatments, and quality improvement strategies. Unlike randomized controlled trials (RCTs), which examine the efficacy of tests, treatments, or quality improvement strategies in highly specified samples, CER addresses their effectiveness in a broader and more diverse set of populations and settings. Second, CER focuses on comparisons of alternative clinical approaches that have demonstrated efficacy in RCTs but may differ with respect to effectiveness in some populations, side effects, or costs. Third, CER may emphasize collection of data on subgroups in order to facilitate individualized decisionmaking. Fourth, CER uses observational or pragmatic research methods designed to enhance generalizability, including treatment allocation and the measurement of outcomes in real-world settings that are relevant to patients. In particular, CER may draw from a more comprehensive set of population outcomes, examining a wider range of harms, as well as benefits, that may be relevant to patients.