Professional bodies assess the quality of relevant studies when developing standards and guidelines. ACOG, for example, uses the following methodology (USPSTF 2001, see ‘Learn More-Primary Sources’) and one can find the specific level of evidence after each reference.
Using the highest level of evidence following data review, ACOG will provided graded recommendations
Level A Recommendations are based on good and consistent scientific evidence
Level B Recommendations are based on limited or inconsistent scientific evidence
Level C Recommendations are based primarily on consensus and expert opinion
The concept of ‘levels of evidence’ follows the NAM standard that quality of evidence should be an integral part of medical guideline development. Note that the NAM does not prescribe a single rating system. Different professional bodies may use different scoring systems. What is important is that ‘levels of evidence’ be readily apparent to the guideline reader. The same approach can be used when reviewing a paper.
Assess the quality of a study by asking 3 basic questions:
(a) Cohort study – these are studies where the starting point is a particular exposure
(b) Case control studies – these are ‘retrospective’ studies – which means that the events or interventions being studied have already taken place in the past and the outcome of interest drives the design, rather than the exposure (see cohort study, above)
Cross sectional studies – At any given time, what is the exposure and outcome?
“Level of evidence” is a standardized way to determine the quality of a research project, which is based on study design. Clinical trials are ‘interventional’, if researchers intervene and are the highest level of evidence, followed by lower levels of evidence where observational approaches are used and ‘nature is allowed to take its course’. Ultimately, the goal of any such rating system is to help clinicians provide evidenced-based care to patients and aid in public health policy.
Please log in to access ObGFirst and the 2T US Atlas
OBG Project CME requires a modern web browser (Internet Explorer 10+, Mozilla Firefox, Apple Safari, Google Chrome, Microsoft Edge). Certain educational activities may require additional software to view multimedia, presentation, or printable versions of their content. These activities will be marked as such and will provide links to the required software. That software may be: Adobe Flash, Apple QuickTime, Adobe Acrobat, Microsoft PowerPoint, Windows Media Player, or Real Networks Real One Player.
This educational activity may contain discussion of published and/or investigational uses of agents that are not indicated by the FDA. The planners of this activity do not recommend the use of any agent outside of the labeled indications.
The opinions expressed in the educational activity are those of the faculty and do not necessarily represent the views of the planners. Please refer to the official prescribing information for each product for discussion of approved indications, contraindications, and warnings.
Participants have an implied responsibility to use the newly acquired information to enhance patient outcomes and their own professional development. The information
presented in this activity is not meant to serve as a guideline for patient management. Any procedures, medications, or other courses of diagnosis or treatment discussed or suggested in this activity should not be used by clinicians without evaluation of their patient’s conditions and possible contraindications and/or dangers in use, review of any applicable manufacturer’s product information, and comparison with recommendations of other authorities.
One of the benefits of an ObGFirst subscription is the ability to earn CME/CE credits from the ObG entries you read. Tap the button to learn more about ObGFirst