<< Community-Acquired Pneumonia: Deciding Which Antibiotics To Use Whom To Admit And Which Antibiotics To Use
Who goes home? Who stays? Decisions regarding disposition depend upon a variety of factors. The most important considerations involve clinical factors such as patient stability, comorbid disease, and ability to take oral medications.42Other considerations include psychosocial issues such as patient preferences, reliability of the patient and family, and resources available at home. Home resources include both family and home healthcare provided by visiting professionals.
The PORT Scoring System
Currently, between 3% and 22% (average, 12%) of all patients hospitalized for pneumonia can probably be treated as outpatients.43There is a tremendous variability in the admission rates for patients with communityacquired pneumonia. This variability often has less to do with the medical condition of the patient than the practice style of the physician. What if there was an objective means to predict the need for hospitalization? It could identify high-risk patients and target them for aggressive therapy. It could distinguish low-risk patients and allow them to be treated at home, saving significant resources.
The PORT cohort study provides physicians with a prediction rule that quantifies the risk of an adverse medical outcome in patients with communityacquired pneumonia. This allows the physician to select the most appropriate site of treatment. The rule wasderived and validated with 52,000 adult inpatients with community-acquired pneumonia, and validated a second time with 2287 adults, both inpatients and outpatients.2The investigators designed a two-step algorithm to stratify patients with community-acquired pneumonia into five risk classes that correlate with mortality (see “PORT Recommendations”). Other researchers have shown that the use of the PORT rules may increase the number of patients with communityacquired pneumonia who may be safely discharged.44The IDSA endorses the PORT study’s recommendations for outpatient treatment of risk classes I and II, brief hospitalization for risk class III, and traditional hospitalization for risk classes IV and V.1
To use the PORT algorithm, follow the decision tree in Part 1. If the patient is younger than 50 and has no high-risk historical factors or physical findings, he or she is assigned to risk class I and requires no further testing apart from pulse oximetry. If the patient is older than 50 or has any high-risk factors, the physician may use the scoring sheet (see Part 2) tocompute the score. Calculating this score does require the use of several laboratory variables.
Exceptions To The PORT Rules
There are important limitations to the PORT prediction rule. In addition to the scoring criteria, three additional factors were almost universally associated with hospitalization in the PORT study: the inability to maintain oral intake, the lack of patient home care support, and the presence of hypoxemia.42
The authors of the PORT study emphasize that the algorithm “must be applied in conjunction with physician judgment.”2Several important considerations are omitted in the prediction rule: intractable nausea and vomiting, psychiatric illnesses, drug and/or alcohol abuse, homelessness, and poor social support. Such patients may receive a low risk class assignment on objective scoring, yet they may still require inpatient therapy.
Alcoholism deserves special consider ation. One large trial specifically examined the impact of alcoholism on pneumonia and found an increase in both morbidity and the need for medical interventions.45Other studies have found different risk factors associated with either a complicated course or increased risk of death from community-acquired pneumonia. (See Table 4.)
Another limitation of the PORT prediction rule is the exclusion of what the authors term “rare conditions.” These include patients with immunosuppression and neuromuscular diseases. Assigning a greater risk for diabetic and immunosuppressed patients seems obvious, but this is absent in the PORT prediction rule. The PORT authors also failed to include measurement of oxygen saturation early in their algorithm. For example, if a previously healthy 40-year-old with normal vital signs and normal mental status had a PaO2 of 55 mmHg, he would be assigned to risk class I. However, the presence of hypoxia, as outlined in the second step of the prediction rule, would dictate admission and treatment with supplemental oxygen. The authors recognized this oversight and in the body of the paper suggested early measurement of oxygen saturation in patients with community-acquired pneumonia, recommending= hospitalization for those with hypoxia.
Finally, because the prediction rule uses dichotomous variables (normal vs abnormal), certain patients have greater risk than the rule predicts. Consider a previously healthy 30-year-old with a systolic blood pressure of 60 mmHg and a heart rate of 130 beats/min and no other abnormalities listed in the algorithm. The prediction rule would assign this patient to risk class II, suggesting outpatient therapy. Hopefully no emergency physician would discharge a patient in septic shock.
Alternatives To Admission
ED discharge to a home IV therapy program is a safe and effective alternative to hospitalization for carefully selected patients, provided appropriate safeguards are in place.46,47
If antibiotics are administered by a visiting nurse, and 24-hour telephone consultation is available, such a program can safely avoid hospitalization and significantly reduce costs associated with community acquired pneumonia.48