Ventilator-Associated Pneumonia: Bridging Global Disparities

Ventilator-associated pneumonia (VAP) is the most frequent hospital-acquired infection in patients receiving invasive mechanical ventilation (IMV) globally. It affects up to 40% of ventilated patients, with mortality rates up to 50% for all-cause mortality and 13% for direct VAP-related mortality. VAP significantly increases hospital length of stay, diagnostic testing, treatment complexity, and costs, averaging $40,144 per case in the U.S., representing a heavy financial burden on healthcare systems. 

Despite global efforts to reduce VAP incidence, persistent barriers remain, including ambiguous definitions, inconsistent terminology across high-income countries (HICs) and low- and middle-income countries (LMICs), and conflicting guidelines. Additionally, because VAP is deemed preventable, there is a tendency in some hospitals to underreport VAP cases to avoid insurance claim rejections or reputational damage.

In the recent issue of CHEST, Nemet et al. (2025) present a secondary analysis from the CERTAIN study, examining the relationship between country income levels and VAP risk while considering local ventilation practices, staffing, and ventilator bundle adherence. Their findings showed that LMICs had a higher adjusted odds ratio (aOR) of 2.11 for VAP compared with HICs. Additionally, higher ICU staffing correlated with reduced VAP risk, with each unit increase in the physician-to-ICU bed ratio associated with an aOR of 0.69 for lower VAP odds, and each unit increase in the nurse-to-ICU bed ratio showing an aOR of 0.88. Ventilator bundle adherence was not significantly linked to reduced VAP risk.

Global VAP prevalence is highly variable, with Europe and LMICs reporting around 18 cases per 1,000 ventilator days, while the U.S. reports only 1 to 2.5 cases per 1,000 ventilator days. However, this discrepancy is partly due to differences in definitions, as U.S. hospitals utilise the ventilator-associated events (VAEs) framework, which encompasses broader categories and differs from the VAP criteria used internationally. Additionally, underreporting of VAP in the U.S. is suspected due to potential financial repercussions, making direct comparisons with U.S. rates problematic.

A major challenge in managing VAP is the lack of a standardised diagnostic definition, leading to inconsistent incidence reporting and difficulties in comparing studies across settings. While the CDC’s VAE criteria aimed to standardise surveillance by including ventilator-associated conditions, infection-related complications, and possible VAP, these definitions have limitations and are not widely implemented globally. Developing universally applicable, practical diagnostic guidelines that work across diverse healthcare settings is essential to reduce conceptual discrepancies and improve VAP surveillance and management.

The CERTAIN study grouped all LMICs together, which may obscure differences between upper-middle-income countries with robust healthcare systems and low-income countries facing critical system challenges. Furthermore, Latin American countries were underrepresented in this study, with only Mexico included, accounting for a mere 3% of the LMIC data. These limitations necessitate cautious interpretation of the findings and underscore the need for future studies with larger, stratified LMIC patient samples and better regional representation.

Optimal ICU staffing recommendations include a nurse-to-patient ratio of 1:2 and a patient-to-intensivist ratio of 7.5:1, supported by respiratory and physical therapists. Adequate staffing not only improves patient care but also reduces healthcare-associated complications like VAP. The CERTAIN study supports advocating for improved resource and personnel allocation, which is vital for reducing VAP incidence, shortening hospital stays, reducing healthcare costs, and improving patient safety. Thus, healthcare systems and insurers should incentivise adequate ICU staffing instead of punitive measures for VAP reporting.

It is also critical to acknowledge that there are gaps in understanding the pathophysiology of VAP. Recent studies show that IMV can cause decreased microbial diversity and significant shifts in the respiratory microbiome. Patients who develop VAP exhibit more profound dysbiosis, with reduced microbial diversity and increased pathogenic bacteria, linking microbial dysbiosis with VAP occurrence. These factors, along with impaired immune responses, may significantly influence VAP pathogenesis, independent of ventilator bundle implementation, staffing ratios, or country income classifications.

To advance VAP prevention and management, it is essential to deepen the understanding of these underlying mechanisms and combat underreporting. Underreporting does not solve the issue but delays solutions and impedes progress. Embracing transparent reporting, investing in research, implementing standardised diagnostic approaches, and advocating for adequate staffing are critical to improving patient care and reducing the global burden of VAP.

Source: Chest
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