Pneumonia severity index

The pneumonia severity index [PSI] or PORT Score is a clinical prediction rule that medical practitioners can use to calculate the probability of morbidity and mortality among patients with community acquired pneumonia.Fine MJ, Auble TE, Yealy DM, Hanusa BH, Weissfeld LA, Singer DE, Coley CM, Marrie TJ, Kapoor WN. A prediction rule to identify low-risk patients with community-acquired pneumonia. "N Engl J Med". 1997 Jan 23;336(4):243–250. PMID 8995086]

Development of the PSI

The rule uses demographics (whether someone is older, and is male or female), the coexistence of co-morbid illnesses, findings on physical examination and vital signs, and essential laboratory findings. This study demonstrated that patients could be stratified into five risk categories, Risk Classes I-V, and that these classes could be used to predict 30-day survival.

Data Source for Derivation & Validation

The rule was derived then validated with data from 38,000 patients from the MedisGroup Cohort Study for 1989, comprising 1 year of data from 257 hospitals across the US who used the MedisGroup patient outcome tracking software built and serviced by Mediqual Systems (Cardinal Health). One significant caveat to the data source was that patients who were discharged home or transferred from the MedisGroup hospitals could not be followed at the 30-day mark, and were therefore assumed to be "alive" at that time. Further validation was performed with the Pneumonia Patient Outcomes Research Team [PORT] (1991) cohort study. This categorization method has been replicated by otherscite journal |author=Aujesky D, Auble TE, Yealy DM, "et al" |title=Prospective comparison of three validated prediction rules for prognosis in community-acquired pneumonia |journal=Am. J. Med. |volume=118 |issue=4 |pages=384–92 |year=2005 |pmid=15808136 |doi=10.1016/j.amjmed.2005.01.006] and is comparable to the CURB-65 in predicting mortality.cite journal |author=Aujesky D, Auble TE, Yealy DM, "et al" |title=Prospective comparison of three validated prediction rules for prognosis in community-acquired pneumonia |journal=Am. J. Med. |volume=118 |issue=4 |pages=384–92 |year=2005 |pmid=15808136 |doi=10.1016/j.amjmed.2005.01.006]

Usage & Application of the PSI

The purpose of the PSI is to classify the severity of a patient's pneumonia to determine the amount of resources to be allocated for care. Most commonly, the PSI scoring system has been used to decide whether patients with pneumonia can be treated as outpatients or as (hospitalized) inpatients. A Risk Class I pneumonia patient can be sent home on oral antibiotics. A Risk Class II-III pneumonia patient may be sent home with IV antibiotics or treated and monitored for 24 hours in hospital. Patients with Risk Class IV-V pneumonia patient should be hospitalized for treatment.

The PSI Algorithm

The PSI Algorithm is detailed below. An [http://pda.ahrq.gov/clinic/psi/psicalc.asp online, automated PSI calculator] is available on the US AHRQ website.

PSI Derivation and Validation Data

Note: % Died refers to 30-day mortality.

References

External links

* [http://www.ahrq.gov/clinic/pneuclin.htm Pneumonia: New Prediction Model Proves Promising]
* [http://pda.ahrq.gov/clinic/psi/psicalc.asp Pneumonia Severity Index Calculator]
* [http://www.mdcalc.com/capneumoniarisk Community-Acquired Pneumonia Mortality Risk for Adults (Pneumonia Patient Outcomes Research Team - PORT) Score Calculator]
* [http://desktop.google.com/plugins/i/pneumonia_3046.html?hl=en Pneumonia Severity Index Calculator for Google Desktop]

* [http://content.nejm.org/cgi/content/full/347/25/2039/F1 Figure 1, Halm E, Teirstein A. Management of Community-Acquired Pneumonia. NEJM 2002 347 (25): 2039]