Risk Stratification: Site-of-Care Decisions

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The Pneumonia Severity Index, or PSI, is a validated risk stratification instrument which can help in identifying CAP patients who can safely be treated with outpatient antibiotics. 

Point values are given for a variety of clinical and laboratory parameters.  The PSI involves calculating a score, which places a given patient into one of 5 risk classes.  Classes I, II, and III are at low risk for death, and may be considered for outpatient treatment.  Risk classes IV and V should usually be hospitalized.

Access our online Pneumonia Severity Index calculator.

Download a PDA version of the PSI calculator.*

Demographic factors Age (in years) Men Women -10 Nursing home resident +10 Coexisting illnesses Neoplastic disease +30 Liver disease +20 Congestive heart failure +10 Cerebrovascular disease +10 Renal disease +10 Findings on physical examination Altered mental status +20 Respiratory rate >= 30/min +20 Systolic blood pressure <90 mm Hg +20 Temperature <35ºC or >= 40ºC +15 Pulse >= 125 beats/min +10 Laboratory and radiographic findings Arterial pH <7.35 +30 Blood urea mitrogen >= 30/mg/dl (11 mmol/liter) +20 Sodium < 130 mmol/liter +20 Glucose >= 250 mg/dl (14 mmol/liter) +10 Hematocrit <30% +10 Partial pressure of arterial oxygen < 60 mm Hg or oxygen saturation < 90% +10 Pleural effusion +10

Stratification of Risk Score
Risk	Risk Class	Score	Mortality
Low	I	Based on algorithm	0.1%	Outpatient treatment
Low	II	<= 70	0.6%
Low	III	71-90	0.9%
Moderate	IV	91-130	9.3%	Hospital admission
High	V	>130	27.0%

* Interactive tool from the Assessment of the Variation and Outcomes of Pneumonia: Pneumonia Patient Outcomes Research Team Final Report. AHRQ Publication No. 97-N009.