Pneumonia Alphabet Soup: Reworking the Recipes (Part 1)

CAP, HAP, NHAP, HCAP, VAP, DAP, NDAP…
 Imagine a bowl of alphabet soup with all these letters floating on the surface. What about the broth surrounding the letters? Taste the soup, close your eyes, and ask, “What else could be in there?”

Now, here are the letters separated into two “bowls,” which shows the complex flavors of pneumonia soups.

Do These Acronyms Point to Root Causes?

As I prepared a talk on aspiration pneumonia, I started grappling with a lot of questions about this alphabet soup of pneumonia acronyms. For the geriatric population, isn’t it more important to find out HOW and WHY a pneumonia developed, rather than WHERE? The frequently used terms of CAP and HCAP do not necessarily point to a root cause of the pneumonia. Are these distinctions really so different or even necessary in the elderly population?

How did we get into this alphabet soup in the first place?

Historical Perspective

In 1981, the Centers for Disease Control and Prevention (CDC) differentiated nosocomial pneumonia from community-acquired pneumonia, producing the first “Guideline for Prevention of Nosocomial Pneumonia.” This addressed Hospital-Acquired Pneumonia (HAP), which is a nosocomial infection – meaning that it occurred while being taken care of in a hospital for 48 hours or more. In 1994, the CDC guidelines were created for Ventilator-Associated Pneumonia (VAP). VAP is a pneumonia that develops more than 48 hours post-intubation. HAP and VAP have been useful labels within the realm of Hospital-Acquired Infections (HAI), as they can push a hospital to perform root cause analyses.

New Term: HCAP

In 2003, the CDC’s revisions reflected a big shift. The healthcare burden moved away from solely acute care hospitals to include other healthcare settings. Therefore, rather than HAP, they used the term Healthcare-Associated Pneumonia (HCAP) which could signify that the pneumonia developed outside of the hospital, but was related to a recent admission.

In 2005, the Infectious Diseases Society of America (IDSA) and the American Thoracic Society (ATS) established new guidelines to further define HCAP. Patients meet the criteria if any of the following occur:

• Hospitalization for 2 days or more in the preceding 90 days
• Resident of a nursing home or extended-care facility
• Home infusion therapy (including antibiotics and patients with long-term indwelling devices)
• Chronic dialysis within 30 days
• Home wound care
• Family member with multi-drug resistant pathogen

Community-Acquired Pneumonia (CAP)

The term Community-Acquired Pneumonia (CAP) has long been used to refer to pneumonia contracted by people who have had no contact with the healthcare system. It can refer to pneumonia caused by bacteria, viruses, fungi, and parasites. While this term may be useful to epidemiologists and infectious disease specialists, the Speech-Language Pathologist (SLP) and treating medical team should view the term with caution. It may inaccurately exclude aspiration and dysphagia issues.

Early on in my career, I remember reading the medical records and thinking, “Oh, it’s just a community-acquired bug; it cannot be from aspiration.” Unfortunately, the label of CAP tends to downplay what may have caused the pathogenic bacteria to enter the lungs in the first place. In discussing community-acquired pneumonia in the elderly, Yoshikawa and Marrie stated: “Aspiration Pneumonia is under-diagnosed in this group of patients.”²² Therefore, labeling the pneumonias based on the causes – rather than the locations – may help guide the appropriate prevention policies and procedures. As noted by Langmore and colleagues: “If the cause of the pneumonia is not found, it is likely to recur.”¹³

What About Prognostic Scales?

Many studies address the high incidence of morbidity and mortality with CAP in elderly patients. Prognostic scales, such as the Pneumonia Severity Index (PSI), were created to classify patients into low-risk versus high-risk classes to predict short-term mortality.^6,7

However, these scales aren’t without limitations. For instance, the scales:

• Don’t address the very old
• Leave out the issue of dysphagia and aspiration
• Do not address the patient’s functional baseline
• Leave out coexisting diseases of COPD and GI diseases ^{13, 8, 17}

These four limitations of the prognostic scales define a large number of patients who are referred for bedside swallowing evaluations. For example, a frail and bedridden elderly patient over the age of 80 who is aspirating has an elevated risk for developing pneumonia and severe complications, especially if there are co-occurring GI and respiratory diseases.

However, the medial team may not suspect an aspiration pneumonia if there are no overt signs of distress with eating and drinking. Silent aspiration has been found to be as high as 71% in elderly patients with CAP, who were otherwise healthy and ambulating prior to the pneumonia.¹⁰ Once oral pathogens are added to the material aspirated, the community-acquired pneumonia may be better labeled as an aspiration pneumonia.

Marik & Kaplan suggested that “all elderly patients with CAP be screened for dysphagia.”¹⁶ The SLP’s job is to determine how, why, and when the dysphagia and aspiration may have occurred (more on that in part 2).

Differences Between HCAP and CAP

There has been controversy around the HCAP label. Some researchers have lumped these HCAP and CAP patients together in their studies, noting no “substantive differences.”²¹ The microbiology of the HCAP pneumonia is not so different from CAP.

A study in the UK by Chalmers, et al., 2011, found differences in HCAP versus the CAP group. In this study, patients with HCAP were older and had:

• Increased frequency of CHF, cerebrovascular disease, and COPD
• Worse premorbid functional status
• Higher frequency of risk factors for aspiration ³

Additionally, the factors associated with multi-drug resistant organisms in patients with HCAP included:

• Presence of risk factors for aspiration
• Chronic lung disease
• Intensive care unit admission³

Researchers advised that these risk factors should be included in the definition of HCAP.

Pneumonia Has Many Factors

Yes, the recipe is complex!

So why classify a pneumonia with only one label when the cause is multifactoral? The word multifactoral comes up again and again in the literature regarding the causes of pneumonia.

There was a perceived shift in the field of speech-language pathology and dysphagia management in 1998 when Langmore, et al. provided data that demonstrated that dysphagia alone is not necessarily the best predictor of who will get an aspiration pneumonia.¹²

In this well-known 4-year prospective study, Langmore and team performed logistic regression analyses to find the best predictors of aspiration pneumonia. They took the 7 best predictors and grouped them into the following 4 categories:

• Medical/health status
• Oral/dental status
• Swallowing/feeding status
• Functional status

In 2002, Langmore and colleagues continued this work in a retrospective study analyzing 55 variables in 102,842 MDS nursing home resident assessments. They found the following predictors of aspiration pneumonia¹³ in people living in nursing facilities:

• Need for suctioning
• Impaired pulmonary clearance (e.g., COPD and CHF)
• Presence of a feeding tube
• Bedfast (including dependence in bed or locomotion)
• Delirium/less alert
• Weight loss
• Presence of dysphagia
• Mechanically altered diet
• Dependence for feeding
• Increased number of medications

The Recipe for Pneumonia

Furthermore, Langmore and her colleagues proposed a model using these predictors to explain the pathogenesis of aspiration pneumonia.

Not to make light of a serious topic, but it has been helpful for me to compile the predictors from both studies into a Recipe for Pneumonia.

1. Begin with an ample number of the essential ingredient: pathogenic microorganisms. Allow them to colonize in the pot, which is the oropharynx and/or stomach. The following predictors will ensure sufficient quantities of this ingredient and foster colonization:
   • Dependency for oral care
   • Large number of decayed teeth
   • Polypharmacy, or large number of medications contributing to xerostomia
   • Tube feeding (alters oral flora due to the NPO status and alters the gastric pH fostering bacterial growth)
2. Mix in a pinch or a dash of aspiration (refluxed material, saliva, food and/or liquid). The following predictors will enhance the odds of getting the recipe right:
   • Need for suctioning may indicate difficulty clearing secretions
   • Tube feeding status
   • Delirium/less alert
   • Dependency on others to provide feedings
   • Presence of dysphagia and need for mechanically altered diet
3. Add mixture to a host with poor pulmonary clearance. The following predictors will help the brew stay in the lungs:
   • Smoking status
   • Bedridden status
   • Diseases like COPD and CHF that cause decreased pulmonary clearance
4. Simmer in the host for the right amount of time. The following predictors will ensure a decreased host resistance and systemic immunologic response to allow lengthy simmering:
   • Weight loss
   • Multiple medical diagnoses

Functional Status

As noted in the factors above, the patient’s functional status may be a more important predictor of outcome than knowing where the pneumonia was acquired. Functionally dependent people had a higher incidence of documented aspirations than the functionally independent subjects.¹⁷

Literature frequently notes that nursing home residents have a higher incidence of pneumonia mortality than community-dwelling elders, but the true indicator may be a poor baseline functional status.¹⁴ We have all seen very debilitated elderly patients who were just barely getting by at home with many services, and their functional baseline may have been lower than some nursing facility residents.

Additionally, advanced age and male gender (sorry men!) frequently have been associated with increased pneumonia risk, increased readmissions, and pneumonia mortality.^{9, 15, 19}

Know the Causes, Do No Harm

All these factors help the medical team take a holistic approach to treatment, seeing all the potential causes and influencing factors. It requires a broad, big-picture view, not focusing solely on one label or one aspiration on a swallow study. For example, if a person has one aspiration of thin liquid on a videofluoroscopic swallow study, the SLP may place him on thickened liquids. This may be too cautious, especially if the person does not have any significant risk factors for developing a pneumonia. Subsequently, if the person refuses the thickened liquids, he may become dehydrated, which has its own severe sequela.

Coyle and Matthews⁵ summarized this issue well:

“Often clinicians forget that other pneumonia risk factors outweigh the potential harm of aspiration, and may use interventions that could pose greater risks to the patient than the swallowing disorder itself.”

In part 2 of this article, we’ll take a closer look at the secret ingredients that go into the recipe for multifactorial aspiration pneumonias, including dysphagia-related and non-dysphagia-related aspiration pneumonias.