The pneumonia

Pneumonia

Pneumonia is an inflammatory condition of the lung—especially affecting the microscopic air sacs —associated with fever, chest symptoms, and a lack of air space on a chest X-ray. Pneumonia is typically caused by an infection but there are a number of other causes...

 severity index [PSI] or PORT Score is a clinical prediction rule that medical practitioners

Medicine

Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

 can use to calculate the probability of morbidity and mortality

Death

Death is the permanent termination of the biological functions that sustain a living organism. Phenomena which commonly bring about death include old age, predation, malnutrition, disease, and accidents or trauma resulting in terminal injury....

 among patients with community acquired pneumonia.

Despite sometimes being used to predict the need for hospitalization in people with pneumonia, the PORT score was not developed to do so and should not be used in that way. Mortality prediction is similar to that when using CURB-65.

Development of the PSI

The rule uses demographics

Demographics

Demographics are the most recent statistical characteristics of a population. These types of data are used widely in sociology , public policy, and marketing. Commonly examined demographics include gender, race, age, disabilities, mobility, home ownership, employment status, and even location...

 (whether someone is older, and is male or female), the coexistence of co-morbid illnesses, findings on physical examination

Physical examination

Physical examination or clinical examination is the process by which a doctor investigates the body of a patient for signs of disease. It generally follows the taking of the medical history — an account of the symptoms as experienced by the patient...

 and vital signs

Vital signs

Vital signs are measures of various physiological statistics, often taken by health professionals, in order to assess the most basic body functions. Vital signs are an essential part of a case presentation. The act of taking vital signs normally entails recording body temperature, pulse rate ,...

, 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

Cardinal Health

Cardinal Health, Inc., is a Fortune 500 health care services company based in Dublin, Ohio. Cardinal Health specializes in health care supply chain services, providing pharmaceuticals and medical products to more than 40,000 locations each day. The company is also a manufacturer of medical and...

). 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 others and is comparable to the CURB-65 in predicting mortality.

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 online, automated PSI calculator is available on the US AHRQ website.

Step 1: Stratify to Risk Class I vs. Risk Classes II-V
	Presence of:
| | Over 50 years of age | Yes/No
| | Altered mental status | Yes/No
| | Pulse ≥125/minute | Yes/No
| | Respiratory rate >30/minute | Yes/No
| | Systolic blood pressure <90 mm Hg | Yes/No
| | Temperature <35°C or ≥40°C | Yes/No
	History of:
| | Neoplastic disease | Yes/No
| | Congestive heart failure | Yes/No
| | Cerebrovascular disease | Yes/No
| | Renal disease | Yes/No
| | Liver disease | Yes/No
| | |
| | If any "Yes", then proceed to Step 2 |
| | If all "No" then assign to Risk Class I |
| | |
Step 2: Stratify to Risk Class II vs III vs IV vs V
	Demographics		Points Assigned
| | If Male | +Age (yr)
| | If Female | +Age (yr) - 10
| | Nursing home resident | +10
	Comorbidity
| | Neoplastic disease | +30
| | Liver disease | +20
| | Congestive heart failure | +10
| | Cerebrovascular disease | +10
| | Renal disease | +10
	Physical Exam Findings
| | Altered mental status | +20
| | Pulse ≥125/minute | +20
| | Respiratory rate >30/minute | +20
| | Systolic blood pressure <90 mm Hg | +15
| | Temperature <35°C or ≥40°C | +10
	Lab and Radiographic Findings
| | Arterial pH <7.35 | +30
| | Blood urea nitrogen ≥30 mg/dl (9 mmol/liter) | +20
| | Sodium <130 mmol/liter | +20
| | Glucose ≥250 mg/dl (14 mmol/liter) | +10
| | Hematocrit <30% | +10
| | Partial pressure of arterial O2 <60mmHg | +10
| | Pleural effusion | +10
| | |
| | ∑ <70 = Risk Class II |
| | ∑ 71-90 = Risk Class III |
| | ∑ 91-130 = Risk Class IV |
| | ∑ >130 = Risk Class V |

PSI Derivation and Validation Data

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	Medisgroup Study (1989)				PORT Validation Study (1991) Cohort
	Derivation Cohort		Validation Cohort		Inpatients		Outpatients		All Patients
Risk Class | no. of pts	% died | no. of pts	% died | no. of pts	% died | no. of pts	% died | no. of pts	% died
I | 1,372	0.4 | 3,034	0.1 | 185	0.5 | 587	0.0 | 772	0.1
II (<70) | 2,412	0.7 | 5,778	0.6 | 233	0.9 | 244	0.4 | 477	0.6
III (71–90) | 2,632	2.8 | 6,790	2.8 | 254	1.2 | 72	0.0 | 326	0.9
IV (91–130) | 4,697	8.5 | 13,104	8.2 | 446	9.0 | 40	12.5 | 486	9.3
V (>130) | 3,086	31.1 | 9,333	29.2 | 225	27.1 | 1	0.0 | 226	27.0
Total | 14,199 | 10.2 | 38,039 | 10.6 | 1343 | 8.0 | 944 | 0.6 | 2287 | 5.2

Note: % Died refers to 30-day mortality.

External links

• Pneumonia: New Prediction Model Proves Promising
• Pneumonia Severity Index Calculator
• Community-Acquired Pneumonia Mortality Risk for Adults (Pneumonia Patient Outcomes Research Team - PORT) Score Calculator
• Pneumonia Severity Index Calculator for Google Desktop
• Figure 1, Halm E, Teirstein A. Management of Community-Acquired Pneumonia. NEJM 2002 347 (25): 2039