Healthcare-Associated Pneumonia: What’s in a Name?

The term “healthcare-associated pneumonia” (HCAP) was introduced in 2005 in the American Thoracic Society (ATS)/Infectious Disease Society of America (IDSA) guidelines for the management of adults with nosocomial pneumonia because of concerns regarding a potentially greater risk of multidrug-resistant pathogens (MDRs) and associated treatment needs among patients with frequent healthcare utilization. ^1,2

According to the ATS/IDSA definition, HCAP referred to patients who had been hospitalized for ≥2 days within the 90 days prior to infection; resided in a nursing home or long-term care facility; attended a hospital or hemodialysis clinic; or received intravenous antibiotic therapy, chemotherapy, or wound care within the 30 days prior to infection.²

Initial findings of elevated mortality rates (20%-25%) in this group lent further support to the use of a distinct label for these patients.¹ Other research suggested that high rates of MDR pathogens — especially Methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, and enterobacteria — may account for the increased mortality observed in patients meeting HCAP criteria.¹ “Therefore, the guideline recommended a broad-spectrum empirical antimicrobial approach to HCAP…, usually including MRSA and double anti-pseudomonas coverage,” wrote Ewig et al, in a systematic review published in Clinical Microbiology and Infection.¹

An increasing body of subsequent research has challenged the usefulness of the HCAP label, including studies that have cast doubt on the links between MDRs and increased mortality, results that showed the label does not accurately identify the presence of MDRs, and research that demonstrated no survival benefit in patients treated in accordance with the ATS/IDSA guidelines for HCAP.¹ One study even noted increased mortality among critically ill patients receiving guideline-concordant treatment.³

As a result of such findings, the HCAP concept was not included in the 2016 version of the ATS/IDSA guidelines on managing nosocomial pneumonia, and the guideline authors explicitly recommended abandoning the term in the 2019 guidelines on managing community-acquired pneumonia (CAP).^4,5

The review by Ewig et al examined studies comparing characteristics between patients with HCAP and patients with CAP. The results revealed that patients meeting HCAP criteria were older and had greater comorbidity and mortality rates ranged from 5% to 33%. “Comorbidity and functional status, but not different microbial patterns, seem to account for increased mortality,” they reported.¹

Patients with HCAP had a higher incidence of MRSA, P aeruginosa, and Enterobacteriaceae. Broad-spectrum treatment according to the previous guideline recommendations failed to reduce mortality in 4 observational studies and the “HCAP criteria performed poorly as a predictive tool to identify MDR pneumonia or pathogens not covered by treatment for CAP.”¹

The researchers noted that the high mortality rate found among patients with frequent healthcare utilization or recent hospitalization should not be surprising, as “[h]ealthcare interactions are a marker of chronic ill health and therefore risk of death, irrespective of the presence of pneumonia or a multidrug-resistant pathogen.”¹ Current evidence supports the “conclusion that the HCAP concept describes a population at increased risk of death, but that the recommendation to treat these patients with broad-spectrum combination antimicrobial treatment does not lead to improved outcomes.”

Editor’s Note: This interview has been lightly edited for length and clarity.

Pulmonology Advisor checked in with the following clinicians to discuss their perspectives on the usefulness of the term HCAP: Patricia Bartley, MD, an infectious disease specialist at Cleveland Clinic in Ohio and Matthew Exline, MD, pulmonologist and critical care specialist at The Ohio State University Wexner Medical Center in Columbus.

Pulmonology Advisor: Ewig et al concludes that the term HCAP should no longer be used to identify patients at risk of MDR pathogens. Do you agree? Why or why not?

Dr Bartley: I agree, HCAP should no longer be used as a predictor of MDR pathogens causing pneumonia.

This classification led to the use of vancomycin and antipseudomonal B-lactam to cover simultaneously for MRSA and P aeruginosa, which did not result in improved patient outcomes. As such, the ATS and IDSA guidelines for diagnosis and treatment of adults with CAP published in October 2019 strongly recommend abandoning the use of the term HCAP.

A special group of patients can develop either MRSA or P aeruginosa pneumonia with these identifiable risk factors:

• Infection in the last year from either pathogen
• Prior positive cultures within the last year, especially in respiratory samples
• Recent hospitalization or parenteral antibiotic exposure in the past 90 days

Of the 10 studies listed in Table 1 in the paper by Ewig et al, the MDR was mainly MRSA. The investigators found poor correlation between HCAP and MDR.¹

The unintended consequences of using broad-spectrum antibiotics to cover MRSA and MDR P aeruginosa (most commonly a combination of vancomycin and piperacillin/tazobactam) include an increased risk of acute renal failure, Clostridioides difficile infection, poor outcomes, and increased mortality.^3,5

To summarize, patients at risk for a poor outcome from pneumonia do not necessarily benefit from epiricial treatment with broad-spectrum antibiotics to cover MRSA and MDR P aeruginosa, as this does not change their outcome.

Dr Exline: The term “HCAP” has proven to not be useful as a guideline for therapy, and I agree with the study investigators and the ATS/IDSA 2019 guidelines that the term should be abandoned.

The concept of HCAP was an attempt to capture the risk of antibiotic resistance in patients from a variety of healthcare settings. This definition was meant to trigger clinicians to treat more aggressively for MDR organisms including MRSA, pseudomonas, and some enterobacteria. Not surprisingly, a definition that implied the same risk for MDR infection in a healthy 28-year-old postpartum woman and her 82-year-old grandmother living is a nursing home was bound to be imprecise.