About Systematic Evidence Reviews and Clinical Practice Guidelines

What is a Systematic Evidence Review?

In 2011, the Institute of Medicine (IOM) defined a systematic evidence review as "a scientific investigation that focuses on a specific question and uses explicit, prespecified scientific methods to identify, select, assess, and summarize the findings of similar but separate studies. It may include a quantitative synthesis (meta-analysis), depending on the available data." Systematic evidence reviews of comparative effectiveness research to learn what is known and not known about the potential benefits and harms of alternative drugs, devices, and other healthcare services provides the best evidence to inform clinical decisions.

The NHLBI appoints expert panels to conduct systematic evidence reviews to enable clinical practice guidelines development. An expert panel is a committee of unpaid experts. The chair and members are chosen mainly for their scientific and clinical expertise. Excluded are individuals with clear financial conflicts and those whose professional or intellectual bias would diminish the credibility of the review.

The expert panel confirms the need for the new systematic evidence review, issues a call for critical questions from the public, defines the final critical questions, establishes screening and selection criteria, and develops the review protocol. An independent entity—with guidance from the expert panel—conducts the study selection and rating, data extraction, and summarizes the evidence. The expert panels use this information to develop graded evidence statements.

What are Clinical Practice Guidelines?

The IOM (2011) defined clinical practice guidelines as "statements that include recommendations intended to optimize patient care that are informed by a systematic review of evidence and an assessment of the benefits and harms of alternative care options." Trustworthy guidelines should be based on a systematic evidence review, developed by panel of multidisciplinary experts, provide a clear explanation of the logical relationships between alternative care options and health outcomes, and provide ratings of both the quality of evidence and the strength of the recommendations.

The NHLBI will form partnerships with professional societies to develop clinical practice guidelines from NHLBI sponsored systematic evidence reviews.

How are Conflicts of Interest Managed?

This section describes how the NHLBI manages conflicts of interest among the members of the writing and review groups:

  • Members voluntarily verbally disclose any potential conflicts of interest to each other during a general meeting, and recuse themselves of voting if they have a potential conflict of interest.
  • A methodologist is hired to work with writing groups to provide objectivity in data analysis and ranking of evidence through the preparation of evidence tables and facilitating consensus.
  • Expert Panels offer opportunities for public review and comments via the NHLBI Website and/or a scheduled public forum.