A comparison of diagnostic algorithms and clinical parameters to diagnose ventilator-associated pneumonia: a prospective observational study

Farshid Rahimibashar,Amir Vahedian-Azimi,Mojtaba H. Yaghoobi,Andrew C. Miller

doi:10.1186/s12890-021-01527-1

Abstract

BackgroundSuspicion and clinical criteria continue to serve as the foundation for ventilator-associated pneumonia (VAP) diagnosis, however the criteria used to diagnose VAP vary widely. Data from head-to-head comparisons of clinical diagnostic algorithms is lacking, thus a prospective observational study was performed to determine the performance characteristics of the Johanson criteria, Clinical Pulmonary Infection Score (CPIS), and Centers for Disease Control and Prevention’s National Healthcare Safety Network (CDC/NHSN) criteria as compared to Hospital in Europe Link for Infection Control through Surveillance (HELICS) reference standard.MethodsA prospective observational cohort study was performed in three mixed medical-surgical ICUs from one academic medical center from 1 October 2016 to 30 April 2018. VAP diagnostic criteria were applied to each patient including CDC/NHSN, CPIS, HELICS and Johanson criteria. Tracheal aspirate cultures (TAC) and serum procalcitonin values were obtained for each patient.ResultsEighty-five patients were enrolled (VAP 45, controls 40). Using HELICS as the reference standard, the sensitivity and specificity for each of the assessed diagnostic algorithms were: CDC/NHSN (Sensitivity 54.2%; Specificity 100%), CPIS (Sensitivity 68.75%; Specificity 95.23%), Johanson (Sensitivity 67.69%; Specificity 95%). The positive TAC rate was 81.2%. The sensitivity for positive TAC with the serum procalcitonin level > 0.5 ng/ml was 51.8%.ConclusionVAP remains a considerable source of morbidity and mortality in modern intensive care units. The optimal diagnostic method remains unclear. Using HELICS criteria as the reference standard, CPIS had the greatest comparative diagnostic accuracy, whereas the sensitivity of the CDC/NHSN was only marginally better than a positive TAC plus serum procalcitonin > 0.5 ng/ml. Algorithm accuracy was improved by adding serum procalcitonin > 0.5 ng/ml, but not positive quantitative TAC.Trial Registration: Not indicated for this study type.

Highlights

Suspicion and clinical criteria continue to serve as the foundation for ventilator-associated pneumo‐ nia (VAP) diagnosis, the criteria used to diagnose VAP vary widely
Algorithm accuracy was improved by adding serum procalcitonin > 0.5 ng/ml, Table 3 Patient demographic and clinical information p-value n = 45 n = 40
VAP: ventilator-associated pneumonia; IQR: interquartile range; Multiple drug resistant (MDR): multiple drug resistant; APACHE: Acute Physiology and Chronic Health Evaluation; ICU: intensive care unit; VAP: ventilator-associated pneumonia; LOS: length-of-stay a Independent sample t-test b Fisher exact test c Chi-square similar to prior reports, the addition of microbiological data to the clinical definitions did not significantly improve the sensitivity or specificity [40]. These findings suggest that combining cohorts based on HELICS and Clinical Pulmonary Infection Score (CPIS) may be reasonable for meta-analysis or population studies, but the same may not be true for studies based on CDC/NHSN criteria as the diagnostic agreement is poor

Summary

Introduction

Suspicion and clinical criteria continue to serve as the foundation for ventilator-associated pneumo‐ nia (VAP) diagnosis, the criteria used to diagnose VAP vary widely. Amongst the most prevalent and threatening ICU NIs is ventilator-associated pneumonia (VAP), which may develop in patients receiving invasive. One component of the Institute for Healthcare Improvement’s recommended ventilator bundle is the accurate diagnosis and determination of VAP incidence [18,19,20]. The optimal VAP diagnostic strategy remains contentious. Research in this field is limited by the lack of a consensus ‘gold standard’ definition against which to test the diagnostic accuracy of new diagnostic algorithms or methods of detection. VAP diagnosis remains challenging as clinical signs and symptoms may be nonspecific, with clinical diagnosis being overly sensitive (leading to increased antibiotic use), and histopathology (ante- or post-mortem within 96 h of death) being limited in availability, consistency, standardization and reliability [21,22,23]. Quantitative respiratory cultures have been found to correlate poorly with histopathology [22, 24]

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