Criteria for Inpatient Treatment of Pneumonia
Use the 2007 IDSA/ATS severe CAP criteria or the PSI/CURB-65 scores to determine hospitalization need, with ICU admission required for patients meeting one major criterion (mechanical ventilation or septic shock) or three minor criteria (respiratory rate >30/min, PaO2/FiO2 <250, multilobar infiltrates, confusion, uremia, leukopenia, thrombocytopenia, hypothermia, or hypotension requiring aggressive fluid resuscitation). 1
General Hospitalization Criteria
Hospitalization is recommended for patients with PSI class IV-V or CURB-65 score ≥2. 1 The decision to hospitalize remains fundamentally clinical but must be validated against at least one objective risk assessment tool 1.
PSI (Pneumonia Severity Index) Risk Classes
- Class IV-V patients require hospitalization due to significantly elevated mortality risk 1
- PSI incorporates age, comorbidities, vital signs, laboratory values, and radiographic findings 1
CURB-65 Score Components (1 point each)
- Confusion (new onset) 1
- Uremia (BUN >7.0 mM or >19.1 mg/dL) 1
- Respiratory rate ≥30 breaths/min 1
- Blood pressure (systolic <90 mmHg or diastolic ≤60 mmHg) 1
- Age ≥65 years 1
Score ≥2 warrants hospitalization; score ≥3 indicates severe pneumonia requiring consideration for ICU admission. 1
ICU Admission Criteria (Severe CAP)
ICU admission is required when patients meet one major criterion OR three or more minor criteria. 1
Major Criteria (Either One Requires ICU)
Minor Criteria (Three or More Require ICU)
- Respiratory rate >30 breaths/min 1
- PaO2/FiO2 ratio <250 (severe respiratory failure) 1
- Multilobar infiltrates (involvement of more than two lobes) 1
- Confusion (altered mental status) 1
- Uremia (BUN ≥20 mg/dL) 1
- Leukopenia (WBC <4,000 cells/mm³) 1
- Thrombocytopenia (platelets <100,000/mm³) 1
- Hypothermia (core temperature <36°C) 1
- Hypotension requiring aggressive fluid resuscitation 1
Alternative British Thoracic Society Criteria
Two or more of the following four criteria also indicate severe pneumonia requiring ICU consideration: 1
Additional Hospitalization Considerations
Non-Medical Factors
Social factors must be incorporated into the admission decision, including inability to take oral medications, lack of reliable caregiver, homelessness, or inability to follow up within 24-48 hours. 1
Comorbidities Favoring Hospitalization
- Chronic heart, lung, liver, or renal disease 1, 2
- Diabetes mellitus 1, 2
- Alcoholism 1, 2
- Malignancy 1, 2
- Asplenia 1, 2
- Immunosuppression 1
Critical Timing and Management Points
All admitted patients must receive their first antibiotic dose within 8 hours of hospital arrival. 1 Delays in appropriate antibiotic therapy significantly increase mortality 3, 4.
Outpatient Follow-Up Requirements
Patients treated as outpatients require clinical reassessment within 24-48 hours, as deterioration most commonly occurs during this window. 1 Approximately 7.5% of initially outpatient-treated patients require subsequent hospitalization and have higher mortality risk 1.
Common Pitfalls to Avoid
Do not rely solely on clinical judgment without validating against objective severity scores—patients transferred to ICU after initial ward admission have higher mortality than those directly admitted to ICU. 1 This reflects "mis-triage" of unrecognized severe pneumonia 1.
When in doubt, hospitalize. 1 Predictors of complicated courses in seemingly low-risk patients exist but have not been validated in independent cohorts 1.
Recognize that PSI and CURB-65 were designed to predict mortality, not necessarily ICU need. 1 For ICU-specific decisions, the 2007 IDSA/ATS severe CAP criteria have superior accuracy 1.