Risk stratification of community-acquired pneumonia to help determine inpatient versus outpatient treatment.
Audience: PRACTITIONER
Published by EVAL Foundation
Revision 3 · Published August 6, 2024
Community acquired pneumonia (CAP) is a common condition that presents in the outpatient setting (primary care and emergency care) with a hospitalization rate of approximately 2% in ages ≥ 65 years and is associated with a 30-day mortality rate of 5% in hospitalized patients (Womack & Kropa, 2022). Further, Womack & Kropa highlight that in 11% of patients a bacterial pathogen was identified, 23% of patients a viral pathogen and 62% of patients no organism was identified. (Note: These studies were conducted before the COVID-19 pandemic.) Diagnosis of community acquired pneumonia (CAP) is usually made with a combination of history, physical exam, and findings on chest x-ray, lung US or chest CT scan. Clinicians are encouraged to use both their clinical judgement and a validated clinical prediction rule to determine the need for hospitalization in patients with CAP (Armstrong, 2020). The Pneumonia Severity (PSI) Pneumonia Patient Outcomes Research Team (PORT) prediction rule is a well-validated risk stratification tool that can assist clinicians in the outpatient setting with determining disposition (inpatient versus outpatient).
However, validated clinical prediction rules, like the PSI/PORT and CURB-65, do not effectively determine the level of care required (Armstrong, 2020). The American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA) criteria for severe CAP is preferred to predict ICU admission.¹ Low-quality evidence suggests the PSI/PORT may outperform CURB-65. Armstrong (2020) reports the PSI/PORT can underestimate the severity of illness among younger patients, but it has higher discriminative power in predicting mortality and a lover false-positive rate then the CURB-65.
¹Statement on COVID-19 (Armstrong, 2020): "Editor's Note: This ATS/IDSA guideline was produced before the COVID-19 pandemic, which has altered the diagnosis and management of lower respiratory tract infections. The current version of this guideline limits testing and antiviral treatment in patients with influenza, and we expect testing for and treatment of severe acute respiratory syndrome coronavirus 2 infection to become a long-standing element of standard pneumonia care.
The Pneumonia Severity (PSI) Pneumonia Patient Outcomes Research Team (PORT) prediction rule is a well-validated risk stratification tool that can assist clinicians in the outpatient setting with determining disposition (inpatient versus outpatient). Diagnosis of community acquired pneumonia (CAP) is usually made with a combination of history, physical exam, and findings on chest x-ray, lung US or chest CT scan. Intended for immunocompetent adults who have not recently traveled internationally.
Rule criteria
| Criteria | Points |
| Age | 1 point per year |
| Sex | Male (0) Female (-10) |
| Nursing home resident | 10 |
| Neoplastic disease¹ | 30 |
| Liver disease history² | 20 |
| Cerebrovascular disease history³ | 10 |
| Renal disease history⁴ | 10 |
| Liver disease history⁵ | 20 |
| Altered mental status⁶ | 20 |
| Pulse ≥ 125 beats/min | 10 |
| Respiratory rate ≥ 30 breaths/min | 20 |
| Systolic blood pressure < 90 mmHg | 20 |
| Temperature < 35°C (95°F) or > 39.9°C (103.8°F) | 15 |
| Pleural effusion on x-ray | 10 |
| pH < 7.35 | 30 |
| BUN ≥ 30 mg/dL or ≥ 11 mmol/L | 20 |
| Sodium < 130 mmol/L | 20 |
| Glucose ≥ 250 mg/dL or ≥ 14 mmol/L | 10 |
| Hematocrit < 30% | 10 |
| Partial pressure of oxygen < 60 mmHg or < 8 kPa⁷ | 10 |
¹Defined as any cancer (except basal- or squamous-cell cancer of the skin) that was active at the time of presentation or diagnosed within one year of presentation.
²Defined as a clinical or histologic diagnosis of cirrhosis or another form of chronic liver disease, such as chronic active hepatitis.
³Defined as a clinical diagnosis of stroke or transient ischemic attack or stroke documented by MRI or CT.
⁴Defined as a history of chronic renal disease or abnormal blood urea nitrogen and creatinine concentrations documented in the medical record.
⁵Defined as a clinical or histologic diagnosis of cirrhosis or another form of chronic liver disease, such as chronic active hepatitis.
⁶Defined as disorientation with respect to person, place, or time that is not known to be chronic, stupor, or coma.
⁷In the Pneumonia PORT cohort study, an oxygen saturation of < 90% on pulse oximetry or intubation before admission was also considered abnormal.
Scoring & Recommendations
The following 11 criteria or risk factors are presented first:
If age is < 51 and the following 10 criteria are "no," then the remaining risk criteria will not be asked, no score is calculated, and the patient is assigned class I which is consistent with the original PORT design study by Fine et al (1997).
| Recommendation | Criteria | Points |
Class I: Outpatient care with oral antibiotics Low Risk: 0.1% mortality risk |
| No points |
Class II: Outpatient care with oral antibiotics Low Risk: 0.6-0.9% mortality |
| ≤ 70 |
Class III: Outpatient or inpatient admission Low Risk: 0.9-2.8% mortality |
| 71-90 |
Class IV: Inpatient admission Moderate Risk: 8.2-9.3% mortality |
| 91-130 |
Class V: Inpatient admission High Risk: 27.0-29.2% mortality |
| > 130 |
Considerations
According to the American Thoracic Society (ATS) and the Infectious Diseases Society of America (IDSA) practice guidelines on patients with community acquired pneumonia (CAP)(Armstrong, 2020; Womack & Kropa, 2022):
¹Statement on COVID-19 (Armstrong, 2020): "Editor's Note: This ATS/IDSA guideline was produced before the COVID-19 pandemic, which has altered the diagnosis and management of lower respiratory tract infections. The current version of this guideline limits testing and antiviral treatment in patients with influenza, and we expect testing for and treatment of severe acute respiratory syndrome coronavirus 2 infection to become a long-standing element of standard pneumonia care.
Current: Revision 3
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