New evidence about best practices and clinical outcomes of various treatments can change the clinical practice guideline recommendations for screening and treatment.

Based on comparisons of serial editions of ACC/AHA guidelines, the authors observed that 4 out of 5 Class I recommendations remained valid across two guideline editions; however, they also noted that 1 out of every 5 Class I recommendations was either downgraded to a less certain status, reversed so as to recommend against a previously endorsed treatment, or omitted entirely.
Neuman and colleagues also found the odds of a downgrade, reversal, or omission to be more than three times greater among recommendations based on retrospective studies, case reports, or expert opinion versus randomized controlled trials.
While the study was not designed to examine the specific reasons that the individual recommendations were downgraded, supplemental analyses suggested that it was uncommon for recommendations to be downgraded as a result of the emergence of new research studies. Instead, Neuman and colleagues found that many of the downgrades in recommendations that they observed may have come from changes over time in how expert physicians interpreted existing medical research.
"Clinical practice guidelines are used by health care providers to make decisions about treatments for individual patients, and by hospitals, regulators, and insurers to develop quality measures," says Neuman. "Our study provides new information about the durability of guideline recommendations over time that can help patients, clinicians, administrators, and regulators make better choices about how guideline recommendations can be used to improve patient outcomes."
Source-Eurekalert