Comparative effectiveness research (CER). The generation and synthesis of evidence that compares the benefits and harms of alternative methods to prevent, diagnose, treat, and monitor a clinical condition or to improve the delivery of care. The purpose of CER is to help consumers, clinicians, purchasers, and policy makers to make informed decisions that will improve health care at both the individual and population levels. Also referred to as clinical effectiveness research, evidence-based medicine, or health technology assessment.

Conflict of interest. A set of circumstances that creates a risk that professional judgment or actions regarding a primary interest will be unduly influenced by a secondary interest.

Consistency. The degree to which estimates of effect for specific outcomes are similar across included studies.

Directness. The extent to which studies in the body of evidence were designed to address the link between the healthcare intervention and a specific health outcome.

Dose–response association. A consistent association across similar studies of a larger effect with greater exposure to the intervention.

Efficiency of conducting review. Avoids unnecessary burden and cost of the process of conducting the review, and allows completion of the review in a timely manner.

Evidence. Information on which a decision or guidance is based. Evidence is obtained from a range of sources, including randomized controlled trials, observational studies, and expert opinion of clinical professionals and/or patients.

Harm. A hurtful or adverse outcome of an action or event, whether temporary or permanent.

Meta-analysis. The process of using statistical methods to combine quantitatively the results of similar studies in an attempt to allow inferences to be made from the sample of studies and be applied to the population of interest.

Patient-centeredness. Respect for and responsiveness to individual patient preferences, needs, and values; helps ensure that patient values and circumstances guide clinical decisions.