When should a patient with pneumonia be admitted to the hospital?

Hospital Admission Decision for Pneumonia

Use objective severity scoring tools (CURB-65 or PSI) to guide admission decisions, but hospitalize any patient with CURB-65 ≥2, hypoxemia (oxygen saturation <92%), or clinical/social factors that preclude safe outpatient management. 1, 2

Primary Severity Assessment Tools

CURB-65 Score (preferred for ease of use):

• Confusion (new onset)
• Urea >19.1 mg/dL (BUN >7.0 mM)
• Respiratory rate ≥30 breaths/min
• Blood pressure: systolic <90 or diastolic ≤60 mmHg
• Age ≥65 years

Score ≥2: Hospitalization strongly recommended 1, 2

• CURB-65 score of 0 carries only 1.2% mortality
• Score of 3-4 carries 31% mortality 1

Pneumonia Severity Index (PSI) (alternative):

• Classes I-III: Generally outpatient candidates (mortality 0.1-2.8%)
• Classes IV-V: Hospitalization required (mortality 8.2-31.1%) 1, 2

Absolute Indications for Hospitalization

Physiologic derangements requiring admission regardless of score: 1, 2

• Oxygen saturation <90-92% on room air or PaO₂ <60 mmHg
• Respiratory rate >30 breaths/min
• Systolic blood pressure <90 mmHg or diastolic <60 mmHg
• Heart rate ≥125 beats/min
• Temperature <35°C or ≥40°C
• Altered mental status or confusion
• Severe dehydration or inability to maintain oral intake

Complications of pneumonia: 1, 3

• Septic shock
• Pleural effusion or empyema
• Cavitation on imaging
• Multilobar involvement
• Metastatic infection

Clinical and Social Factors Mandating Admission

Even low-risk patients (PSI I-III or CURB-65 <2) require hospitalization if: 1

• Inability to reliably take or tolerate oral medications
• Intractable vomiting
• Exacerbation of underlying disease (COPD, heart failure, diabetes)
• No caregiver available or patient is dependent
• Homelessness or inadequate social support
• Severe psychiatric illness or cognitive dysfunction
• Injection drug abuse
• Poor overall functional status
• Failure to respond to previous adequate outpatient antibiotic therapy

High-risk comorbidities warranting lower threshold for admission: 3

• Immunocompromised status (HIV, transplant, chemotherapy, chronic steroids)
• Moderate to severe COPD
• Heart failure
• Chronic liver disease
• Chronic renal disease
• Active malignancy
• Diabetes mellitus

Laboratory and Radiographic Criteria

Abnormalities suggesting need for hospitalization: 3

• Leukopenia (<4,000/μL) or severe leukocytosis (>30,000/μL)
• Acute renal impairment (creatinine >2 mg/dL or increase >2 mg/dL)
• Severe anemia
• Arterial blood gas abnormalities or acidosis
• Coagulation abnormalities

Radiographic findings: 3

• Multilobar involvement
• Pleural effusion
• Cavitation
• Rapid radiographic progression

ICU Admission Criteria

Direct ICU admission required for: 1, 3

• Septic shock requiring vasopressors
• Acute respiratory failure requiring intubation and mechanical ventilation

ICU or high-level monitoring recommended when ≥3 minor criteria present: 1

• Respiratory rate ≥30 breaths/min
• PaO₂/FiO₂ ratio <250
• Multilobar infiltrates
• Confusion
• BUN ≥20 mg/dL
• Leukopenia from infection (WBC <4,000/μL)
• Thrombocytopenia (platelets <100,000/μL)
• Hypothermia (core temperature <36°C)
• Hypotension requiring aggressive fluid resuscitation

Additional ICU considerations: 3

• Urine output <20 mL/h
• Need for mechanical ventilation
• Severe metabolic acidosis
• Disseminated intravascular coagulation
• Acute renal failure requiring dialysis

Critical Clinical Pitfalls

Common errors to avoid: 1

• Over-relying on scoring systems without clinical judgment—a young, previously healthy patient with severe hypotension and tachycardia may score low-risk but requires admission
• Discharging elderly patients (>65 years) without considering functional status and social support
• Failing to reassess outpatients within 24-48 hours—deterioration most likely occurs in this window 1
• Missing hypoxemia in patients who don't appear cyanosed—always measure oxygen saturation objectively 2

When in doubt, hospitalize 1—approximately 7.5% of patients initially treated as outpatients require subsequent hospitalization within 10 days and have higher mortality risk

Outpatient Management Requirements

Patients treated as outpatients must: 1

• Have clinical reassessment planned within 24-48 hours
• Be able to reliably take oral medications
• Have adequate caregiver support
• Understand warning signs requiring immediate return
• Have no concerning social barriers to care