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Pneumonia Severity Index (PSI) for Community Acquired Pneumonia

Demographic factors

Nursing home resident

Comorbid illnesses1

1 Definitions of comorbid illnesses

  • Neoplastic disease: 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.
  • Liver disease: a clinical or histologic diagnosis of cirrhosis or another form of chronic liver disease, such as chronic active hepatitis.
  • Congestive heart failure: systolic or diastolic ventricular dysfunction documented by history, physical examination, and chest radiograph, echocardiogram, multiple gated acquisition scan, or left ventriculogram.
  • Cerebrovascular disease: a clinical diagnosis of stroke or transient ischemic attack or stroke documented by magnetic resonance imaging or computed tomography.
  • Renal disease: a history of chronic renal disease or abnormal blood urea nitrogen and creatinine concentrations documented in the medical record.
Neoplastic disease

Liver disease

Congestive heart failure

Cerebrovascular disease

Renal disease

Physical examination findings
Altered mental status2

2 Altered mental status is defined as disorientation with respect to person, place, or time that is not known to be chronic, stupor, or coma.
Respiratory rate >= 30/minute

Systolic blood pressure < 90 mmHg

Temperature < 35oC (95oF) or >= 40oC (103.8oF)

Pulse >= 125/minute

Laboratory and radiographic findings
Arterial pH < 7.35

Blood urea nitrogen >= 30 mg/dL (11 mmol/L)

Sodium < 130 mEq/L

Glucose >= 250 mg/dL (14 mmol/L)

Hematocrit < 30%

Partial pressure of arterial oxygen < 60 mmHg3

3In the Pneumonia Patient Outcome Research Team (PORT) cohort study, an oxygen saturation value < 90% on pulse oximetry or intubation before admission was also considered abnormal.
Pleural effusion (on x-ray)




  1. Risk class interpretation (30-day mortality, observed in validation cohorts)
Class I:     0.1% Mortality. Candidates for outpatient treatment.
Class II (<= 70 Points):    0.6% Mortality. Candidates for outpatient treatment.
Class III (71–90 Points):   0.9–2.8% Mortality. Outpatient treatment vs brief inpatient observation (based on clinical judgement).
Class IV (91–130 Points): 8.2–9.3% Mortality. Inpatient care.
Class V (131–395 Points): 27.0–29.2% Mortality. Inpatient care.