Evidence supporting recommendations from international guidelines on treatment, diagnosis, and prevention of HAP and VAP in adults

Clinical practice guidelines (CPGs) are intended to support clinical decisions and should be based on high-quality evidence. The objective of the study was to evaluate the quality of evidence supporting the recommendations issued in CPGs for therapy, diagnosis, and prevention of hospital-acquired and ventilator-associated pneumonia (HAP/VAP). CPGs released by international scientific societies after year 2000, using the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) methodology, were analyzed. Number and strength of recommendations and quality of evidence (high, moderate, low, and very low) were extracted and indexed in the aforementioned sections. High-quality evidence was based on randomized control trials (RCT) without important limitations and exceptionally on rigorous observational studies. Eighty recommendations were assessed, with 7 (8.7%), 24 (30.0%), 29 (36.3%), and 20 (25.0%) being supported by high, moderate, low, and very low-quality evidence, respectively. Highest evidence degree was reported for 26 prevention recommendations, with 7 (26.9%) supported by high-quality evidence and no recommendation based on very low-quality evidence. In contrast, among 9 recommendations for diagnosis and 45 for therapy, none was supported by high-quality evidence, in spite of being recommended as strong in 33.3% and 46.7%, respectively. Among HAP/VAP diagnosis recommendations, the majority of evidence was rated as low or very low-quality (55.6% and 22.2%, respectively) whereas among HAP/VAP therapy recommendations, 4/5 were rated as low and very low-quality (40% each). In conclusion, among HAP/VAP international guidelines, most recommendations, particularly in therapy, remain supported by observational studies, case reports, and expert opinion. Well-designed RCTs are urgently needed.