Arms-Based Meta-Analysis of Microbiological Endpoints of 88 VAP Prevention Studies Using Antimicrobial Versus Non-Antimicrobial Strategies—Towards ‘VAP-Zero’?

<b>Background/Objectives:</b> In traditional contrast-based meta-analyses of randomized concurrent controlled trials (RCCTs), topical antibiotic prophylaxis (TAP) appears more effective than either antiseptic-based or non-antimicrobial-based interventions for preventing ventilator-associated pneumonia (VAP). The objective here is to use arm-based methods to determine whether this effectiveness translates towards achieving VAP-zero, both overall and specifically for VAP in association with <i>Staphylococcus aureus</i>, <i>Pseudomonas aeruginosa</i>, and <i>Acinetobacter</i> species among the same RCCTs. <b>Methods</b>: Data were extracted from RCCTs sourced primarily from Cochrane reviews of VAP prevention interventions. Arms-based and contrast-based methods of meta-analyses of the VAP prevention effect size and the VAP incidence per 100 patients receiving mechanical ventilation were obtained using random effects methods. <b>Results</b>: The VAP prevention intervention effect sizes derived by contrast-based versus arms-based meta-analyses were similar for each of the three broad types of interventions. The overall VAP prevention effect of antibiotic-based interventions by contrast-based and arms-based methods were 0.39 (95% confidence interval 0.33 to 0.46; n = 28) versus 0.39 (95% confidence interval 0.32 to 0.47; n = 28), respectively. Surprisingly, the arms-based analysis revealed that the summary VAP incidence, both overall and for each of <i>Staphylococcus aureus</i>, <i>Pseudomonas aeruginosa</i>, and <i>Acinetobacter</i> species within antibiotic intervention groups, were similar to the respective summary incidences within intervention groups of non-antimicrobial RCCTs. <b>Conclusions</b>: VAP-zero, both overall and in association with specific microbial sub-types, has remained elusive using antimicrobial-based interventions. This inference was not evident from a contrast-based analysis.