What is Hospital-Acquired Pneumonia (HAP)?

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Last updated: February 13, 2025View editorial policy

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From the Guidelines

Hospital-Acquired Pneumonia (HAP) is an infection of the pulmonary parenchyma caused by pathogens present in hospital settings.

Definition and Epidemiology

  • HAP is defined as pneumonia that develops in patients admitted to the hospital for more than 48 hours, with an incubation period of at least 2 days 1.
  • The incidence of HAP ranges from 5 to more than 20 cases per 1000 hospital admissions, with the highest rates in immunocompromised, surgical, and elderly patients 1.
  • HAP is the second most common nosocomial infection and the leading cause of death from nosocomial infections in critically ill patients 1.

Types of HAP

  • Ventilator-Associated Pneumonia (VAP): develops in ICU patients who have been mechanically ventilated for at least 48 hours 1.
  • Non-Ventilator HAP: occurs in patients admitted to the hospital for at least 48 hours, without mechanical ventilation 1.

Clinical Impact

  • HAP and VAP increase duration of hospitalization and healthcare costs, with a mean attributable cost of VAP estimated to be approximately $40,000 per patient 1.
  • HAP is associated with an approximate mortality rate of 20% in the ICU, with an estimated attributable mortality of 5-13% 1.
  • HAP is also responsible for increased morbidity, including increased duration of mechanical ventilation, ICU and hospital length-of-stay, and overuse of healthcare resources 1.

From the Research

Definition and Overview of Hospital-Acquired Pneumonia (HAP)

  • Hospital-acquired pneumonia (HAP) is a type of nosocomial infection that occurs in hospitalized patients, with mortality rates approaching 62% 2.
  • HAP is the second most common cause of nosocomial infection overall, but is the most common cause documented in the intensive care unit setting 2.
  • HAP and its subtype, ventilator-associated pneumonia (VAP), remain significant causes of morbidity and mortality worldwide 3.

Causes and Risk Factors of HAP

  • HAP can be caused by various pathogens, including antibiotic-resistant bacteria, and is associated with excess mortality and increased medical care costs 4.
  • The risk factors for HAP include the need for mechanical ventilation, with VAP being the most common nosocomial infection among patients with acute respiratory failure 4.
  • Prior detection of risk factors, combined with clear clinical judgment based on clinical scores and inflammatory biomarkers, is crucial for a well-established management plan 3.

Diagnosis, Management, and Prevention of HAP

  • The diagnosis of HAP can be challenging, especially in the intensive care unit, due to the complexity of critically ill patients 5.
  • The management of HAP involves antimicrobial treatment, nonantimicrobial management, and prevention strategies, including the use of evidence-based guidelines and bundle of care principles 2, 3.
  • Prevention and risk-reduction strategies, such as clinical strategies aimed at preventing HAP and VAP, should be employed in all hospital settings caring for patients at risk for these infections 4.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Clinical practice guidelines for hospital-acquired pneumonia and ventilator-associated pneumonia in adults.

The Canadian journal of infectious diseases & medical microbiology = Journal canadien des maladies infectieuses et de la microbiologie medicale, 2008

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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