Table 2.

Scoring systems to guide ICU admission in CAP (note that other scoring systems exist but that a selection of the most widely studied are included here for clarity and brevity)

Score name	Variables	Comments
IDSA/ATS 2007 criteria	Major: Requirement for mechanical ventilation or vasopressors Minor: Respiratory rate ≥ 30 breaths per min, PaO2/FIO2 ratio ≤ 250, multilobar infiltrates, confusion/disorientation, uremia BUN level ≥ 20 mg/dl, leukopenia WBC count < 400 cells/mm3, thrombocytopenia with platelet count < 100,000 cells/mm3, hypothermia- core temperature > 36 °C, hypotension requiring aggressive fluid resuscitation	Minor criteria show good discrimination for mortality or ICU admission in different healthcare systems Some criteria such as hypoxemia, confusion and hypotension are more discriminatory than others but are awarded the same number of “points”
Simplified IDSA/ATS minor criteria	Respiratory rate ≥ 30 breaths per min, PaO2/FIO2 ratio ≤ 250, multilobar infiltrates, confusion/disorientation, uremia BUN level ≥ 20 mg/dl, systolic blood pressure < 90 mmHg	Simplified version of the above focusing on the most frequent and discriminating variables
SMART-COP	S- systolic BP less than 90 mm Hg (2 points) M- multilobar CXR involvement (1 point) A- albumin less than 35 g/L (1 point) R-respiratory rate 30 br/min or more (1 point), tachycardia 125 bpm or more (1 point), confusion (1 point), low oxygenation (age dependent threshold- 2 points), P- Ph < 7.35 (2 points)	Similar to the IDSA/ATS minor criteria but awards points to highlight the most discriminating variables More complex to calculate than the IDSA/ATS criteria
CURB65	Confusion Urea > 7 mmol/L Respiratory rate ≥ 30/min Blood pressure < 90 mmHg systolic or ≤ 60 mmHg diastolic Age ≥ 65 years	Simple to use and excellent prediction of mortality Poor predictor of ICU admission and should not be used to guide ICU
Pneumonia severity index	Multiple components including age, gender, comorbidity, physical examination findings, laboratory and radiographic findings	Excellent prediction of 30-day mortality Does not predict ICU admission and should not be used for this purpose
SCAP tool	Arterial PH < 7.3, Systolic blood pressure < 90 mmHg, respiratory rate > 30/min, altered mental status, BUN > 30 mg/dl, oxygen arterial pressure < 54 mmHg or PaO2:FiO2 ratio < 250, Age ≥ 80 years, multilobar or bilateral consolidation	Similar variables to the IDSA/ATS criteria and SMART-COP

ICU intensive care unit, CAP community-acquired pneumonia, SCAP severe community-acquired pneumonia; IDSA/ATS Infectious Diseases Society of America and the American Thoracic Society, PaO₂/FiO₂ ratio of arterial oxygen tension to inspired oxygen fraction, BUN blood urea nitrogen, WBC white blood cells