Among clinical practice guidelines for therapy, diagnosis, and prevention of hospital-acquired and ventilator-associated pneumonia (HAP/VAP), most recommendations were found to be supported by observational studies, case reports, and expert opinion rather than randomized controlled trials (RCTs). These findings, gathered from a meta-analysis of clinical practice guidelines published in the European Journal of Clinical Microbiology and Infectious Diseases, show a critical need for well-designed RCTs to guide clinical management of HAP/VAP.

Investigators used the Grades of Recommendation, Assessment, Development, and Evaluation methodology to assess 80 clinical practice guidelines released by international scientific societies since 2000. The number and strength of the recommendations were indexed as high, moderate, low, and very low. High-quality evidence was based on RCTs without important limitations and on rigorous observational studies.

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Of the 80 recommendations assessed, 8.7%, 30.0%, 36.3%, and 25.0% were supported by high-, moderate-, low-, and very low-quality evidence, respectively. Twenty-six prevention recommendations had the highest reported evidence degree with 26.9% being supported by high-quality evidence and no recommendation based on very low-quality evidence. However, among 9 recommendations for diagnosis and 45 for therapy, none were supported by high-quality evidence despite being recommended as strong in 33.3% and 46.7%, respectively.

The majority of evidence among HAP/VAP diagnosis recommendations was rated low or very low; 55.6% and 22.2%, respectively. Among HAP/VAP therapy recommendations, 4/5 were rated as low- and very low-quality; 40% each.

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Investigators noted several limitations in their study, including the possibility that new evidence was published since the most recently assessed guideline was written in 2017.  The literature supporting each recommendation also was not revised, and the quality of evidence was not reassessed. The rating analyses for evidence and recommendations were based on the classifications reported in the original papers. Finally, clinical practice guidelines on HAP/VAP issued by other scientific societies without explicitly reported recommendations or quality-of-evidence assessment were excluded.

According to investigators, the results, “point out the difficulty of performing RCTs and providing high-quality evidence in critically ill patient.” They also reveal research opportunities in areas in which high-quality evidence is scarce. Because most recommendations—especially regarding treatment—were based on observational studies, case reports, and expert opinion, investigators stress the need for large, well-conducted, multicentric RCTs on HAP and VAP.


Campogiani L, Tejada S, Ferreira-Coimbra J, Restrepo MI, Rello J. Evidence supporting recommendations from international guidelines on treatment, diagnosis, and prevention of HAP and VAP in adults [published online December 10 2019]. Eur J Clin Microbiol Infect Dis. doi: 10.1007/s10096-019-03748-z