Pneumonia Severity Index Calculator

Q: How is the PSI different from CURB-65?

The Pneumonia Severity Index uses 20 variables to sort patients into five mortality classes and is especially good at identifying low-risk patients who can be treated as outpatients. CURB-65 uses only five items (confusion, urea, respiratory rate, blood pressure, and age 65 or older), so it is faster at the bedside but less granular. The PSI was derived and validated on a larger cohort and gives finer risk stratification, at the cost of needing labs and a chest x-ray.

Q: What are the PSI risk class cutoffs?

Class I is assigned by a screening step (age under 50 with no listed comorbidities or exam abnormalities), not by points. For everyone else the point total sets the class: Class II is 70 points or fewer, Class III is 71 to 90, Class IV is 91 to 130, and Class V is more than 130 points.

Q: How does the score adjust for age and sex?

Age is the largest single contributor. For men, the demographic points equal the age in years. For women, the points equal the age minus 10. That 10-point reduction reflects the lower age-adjusted pneumonia mortality observed in women in the original derivation cohort.

Q: Why does nursing-home residence add points?

Nursing-home residents had higher pneumonia mortality in the derivation study, so residence adds a fixed 10 points to the demographic base. Note that nursing-home residence does not count toward the Class I screening step — only age, the five comorbidities, and the five exam findings do.

Q: What is the 30-day mortality for Class V?

Class V, the highest-risk group (more than 130 points), had about 27% 30-day mortality in the original derivation cohort. These patients generally warrant inpatient admission and often ICU-level care, guided by the full clinical picture.

Q: When should I use CURB-65 instead of the PSI?

CURB-65 trades granularity for speed and needs no imaging, so it is convenient at the bedside before labs return. The PSI's 20 variables give finer stratification and are strongest at confirming who is safe for outpatient care, but require labs and a chest x-ray. Many clinicians screen with CURB-65 first and use the PSI once the full data set is available to support the admission decision.

Risk Class	Point Total	30-Day Mortality	Typical Disposition
Class I	Screen (age < 50, no comorbidity/exam finding)	0.1%	Outpatient
Class II	≤ 70	0.6%	Outpatient
Class III	71–90	0.9%	Outpatient or brief observation
Class IV	91–130	9.3%	Inpatient admission
Class V	> 130	27.0%	Inpatient (consider ICU)

Group	Item	Points
Demographics	Age (men)	= age in years
Demographics	Age (women)	= age − 10
Demographics	Nursing-home resident	+10
Comorbidity	Neoplastic disease	+30
Comorbidity	Liver disease	+20
Comorbidity	Congestive heart failure	+10
Comorbidity	Cerebrovascular disease	+10
Comorbidity	Renal disease	+10
Exam	Altered mental status	+20
Exam	Respiratory rate ≥ 30/min	+20
Exam	Systolic BP < 90 mmHg	+20
Exam	Temperature < 35°C or ≥ 40°C	+15
Exam	Pulse ≥ 125/min	+10
Lab / imaging	Arterial pH < 7.35	+30
Lab / imaging	BUN ≥ 30 mg/dL	+20
Lab / imaging	Sodium < 130 mmol/L	+20
Lab / imaging	Glucose ≥ 250 mg/dL	+10
Lab / imaging	Hematocrit < 30%	+10
Lab / imaging	PaO₂ < 60 mmHg / SaO₂ < 90%	+10
Lab / imaging	Pleural effusion on x-ray	+10

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Walk-through

How to Use This Calculator

3 steps

1

Enter age and sex

Type the patient's age in years and choose sex. Age is the largest single contributor: for men the demographic points equal the age, and for women they equal the age minus 10. The class recalculates on every change.

2

Check every finding that applies

Work down the Demographics, Comorbidities, Exam findings, and Labs & imaging groups and tick each item that is present — nursing-home residence, the five comorbidities, the five exam abnormalities, and the seven lab or radiographic findings. Each carries the fixed Fine 1997 point weight shown on its chip.

3

Read the class and mortality, then check the tables

The result card shows the total PSI points, the assigned Risk Class (I–V), and the matching 30-day mortality. Open the Risk Class tab for the full class-to-mortality table and the Item Checklist tab for every scored item. Remember Class I is a screening shortcut, not a point total.

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Reference

Formula & Methodology

5 formulas

Total PSI point score

Points = Demographic base + Σ(Comorbidity pts) + Σ(Exam pts) + Σ(Lab / imaging pts)

The PSI/PORT rule (Fine MJ et al., 1997) sums integer points across 20 items. The demographic base plus any checked comorbidity, exam, and lab findings give a total that maps to Risk Class II–V. The two heaviest single items are neoplastic disease and arterial pH < 7.35, each worth 30 points.

Demographic base

Age pts = age (men) or age − 10 (women); + 10 if nursing-home resident

Age contributes its value directly for men and its value minus 10 for women, reflecting women's lower age-adjusted pneumonia mortality in the derivation cohort. Living in a nursing home adds a fixed 10 points.

Comorbidity, exam, and lab points

Neoplastic 30 · Liver 20 · CHF 10 · Cerebrovascular 10 · Renal 10 | Altered mental 20 · RR≥30 20 · SBP<90 20 · Temp<35 or ≥40 15 · Pulse≥125 10 | pH<7.35 30 · BUN≥30 20 · Na<130 20 · Glucose≥250 10 · Hct<30% 10 · PaO₂<60/SaO₂<90 10 · Effusion 10

Each finding, when present, adds its fixed weight to the running total. Thresholds are the published boundaries — for example, respiratory rate is scored at 30/min or more, and arterial pH at below 7.35.

Class I screening step (runs first)

Class I ⇔ age < 50 AND no comorbidity AND no exam abnormality

Before any points are summed, a patient younger than 50 with none of the five comorbidities and none of the five exam abnormalities is assigned Risk Class I. Nursing-home residence and every lab / imaging finding are excluded from this screen. If any screen item is present, the patient is scored and placed in Class II–V by the point total.

Points to class and 30-day mortality

II ≤ 70 (0.6%) · III 71–90 (0.9%) · IV 91–130 (9.3%) · V > 130 (27.0%) · I = screen (0.1%)

The point total sets Class II–V and the associated 30-day mortality from the Fine 1997 derivation cohort. Class I carries the lowest mortality (0.1%) and is assigned only through the screening step above, never by a low point total.

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High YMYL

Trust, Methodology & Sources

Reviewed by Calculover Editorial Review · Updated 2026-07-22 · 2 sources

Editorial accountability

Author: Quinn Sumner - Editor

Owner: Quinn Sumner - Editorial owner

Reviewer: Calculover Editorial Review - Clinical-source review

Last reviewed: 2026-07-22

Last verified: 2026-07-22

Data effective: 2026-07-22

Methodology

The calculator implements the PSI/PORT prediction rule (Fine MJ, Auble TE, Yealy DM, et al., N Engl J Med 1997;336:243-50). It sums the published integer point weights across 20 items — a demographic base (age, sex, nursing-home residence), five comorbidities, five exam findings, and seven lab / radiographic findings — and maps the total to Risk Class II–V with the derivation-cohort 30-day mortality (Class II ≤70, III 71–90, IV 91–130, V >130). Risk Class I is applied as a screening step before scoring: age under 50 with no comorbidity and no exam abnormality. All point values and class cutoffs were cross-verified across MDCalc, Omnicalculator, MDApp, and QxMD reproductions of the original rule.

Assumption: Every finding is entered as already thresholded against the published cutoffs (e.g. respiratory rate ≥ 30/min, arterial pH < 7.35, BUN ≥ 30 mg/dL, glucose ≥ 250 mg/dL).

Assumption: The Class I screening step uses an age boundary of under 50 years and excludes nursing-home residence and all lab / imaging findings, consistent with the cross-checked sources.

Assumption: 30-day mortality figures are the single derivation-cohort values from Fine 1997 (0.1% / 0.6% / 0.9% / 9.3% / 27% for Classes I–V).

Limitations & guidance

The PSI predicts 30-day mortality for community-acquired pneumonia and is validated in adults; it should not be applied to children or to hospital-acquired pneumonia.

The score does not capture oxygenation trends, social support, drug interactions, or the trajectory of illness, and must not be the sole basis for an admission or discharge decision.

Class boundaries and mortality reflect the original derivation cohort; local case mix, pathogens, and care patterns can shift observed outcomes.

Professional guidance: This calculator is for education only and is not medical advice, diagnosis, or treatment. The PSI/PORT score supports, but does not replace, the judgment of a licensed clinician and local pneumonia protocols; disposition decisions require full clinical assessment.

Primary sources

A prediction rule to identify low-risk patients with community-acquired pneumonia - Fine MJ, Auble TE, Yealy DM, et al., New England Journal of Medicine, 1997

PSI/PORT Score: Pneumonia Severity Index for CAP - MDCalc

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Glossary

Key Terms Explained

8 terms

Pneumonia Severity Index (PSI) A 20-item prediction rule (Fine 1997) that sums points from demographics, comorbidities, exam findings, and labs to sort community-acquired pneumonia patients into five 30-day mortality risk classes.

PORT Score An alternative name for the PSI, after the Pneumonia Patient Outcomes Research Team (PORT) that derived and validated the rule.

Risk class One of five strata (I–V) that group patients by predicted 30-day mortality; higher classes carry higher mortality and generally support inpatient rather than outpatient care.

Comorbidity A coexisting chronic condition. The PSI scores five: neoplastic disease, liver disease, congestive heart failure, cerebrovascular disease, and renal disease.

Nursing-home resident A patient residing in a long-term care facility at presentation; it adds 10 points to the demographic base but is not part of the Class I screening step.

Mortality risk The probability of death within 30 days for the patient's risk class, taken from the original PSI derivation cohort (0.1% for Class I up to 27% for Class V).

Community-acquired pneumonia Pneumonia contracted outside a hospital or care setting; the PSI was derived and validated in adults presenting with community-acquired pneumonia.

Altered mental status New disorientation, confusion, or reduced level of consciousness at presentation; one of the five exam findings, worth 20 points in the PSI.

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Scenarios

Real-World Examples

3 worked examples

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Class I — low risk

45-year-old man, previously healthy

Age 45 yr Sex Male Comorbidities / exam none Pleural effusion yes

Points sum to 45 + 10 (effusion) = 55, yet the patient is Risk Class I with 0.1% 30-day mortality. Because he is under 50 with no comorbidities and no exam abnormalities, the screening step assigns Class I before any points matter — and lab / imaging findings such as a pleural effusion do not count toward that screen. Class I patients are typically managed as outpatients.

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Class III — borderline

68-year-old woman with heart failure

Age 68 yr Sex Female Congestive heart failure yes BUN ≥ 30 mg/dL yes

Points sum to (68 − 10) + 10 (CHF) + 20 (BUN) = 88, which falls in the 71–90 range → Risk Class III, with 0.9% 30-day mortality. Class III patients sit on the outpatient / brief-observation boundary; the decision typically weighs oxygenation, comorbidity, and social support alongside the score.

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Class V — high risk

82-year-old man from a nursing home

Age 82 yr Sex Male Nursing-home resident yes Neoplastic disease yes Altered mental status + RR ≥ 30 yes Arterial pH < 7.35 yes

Points sum to 82 + 10 (nursing home) + 30 (neoplastic) + 20 (altered mental status) + 20 (RR ≥ 30) + 30 (pH < 7.35) = 192, well above 130 → Risk Class V, with about 27% 30-day mortality — the highest-risk group. This profile generally prompts inpatient admission and consideration of ICU-level care.

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Deep Dive

Understanding the Pneumonia Severity Index (PORT Score)

3 chapters · 4 min read

The Pneumonia Severity Index turns 20 routine findings — age and sex, nursing-home residence, five comorbidities, five exam abnormalities, and seven lab or radiographic results — into a 30-day mortality risk class for adults with community-acquired pneumonia. It is one of the most extensively validated pneumonia risk tools and is used mainly to identify low-risk patients who can safely be treated as outpatients.

How the PSI is scored

The rule was derived from more than 14,000 patients and validated on over 40,000 (Fine MJ et al., N Engl J Med 1997). Each of the 20 items carries a fixed integer weight; the weights are summed to a total that maps to Risk Class II–V. Age dominates the score because it contributes its full value (men) or its value minus 10 (women). The two heaviest single items are neoplastic disease and an arterial pH below 7.35, each worth 30 points.

This calculator implements the transparent point table and reports the derivation-cohort 30-day mortality for each class.

Risk Class I is a screening shortcut, not a low score

The single most common mistake in implementing the PSI is assigning Class I to any patient with a low point total. Class I is instead a screening step that runs before scoring: a patient younger than 50 with none of the five comorbidities and none of the five exam abnormalities is Class I. Crucially, nursing-home residence and every lab or imaging finding are excluded from this screen — so a healthy 45-year-old with an abnormal lab is still Class I, while a 55-year-old with zero risk factors is Class II, not Class I. This calculator applies the screen first and shows the point total for reference.

How it guides disposition and its limits

The PSI is strongest at confirming who is safe for outpatient care: Classes I–III carry low 30-day mortality and often support outpatient or brief-observation management, while Classes IV–V generally warrant admission, and Class V often ICU-level care. The score is a decision aid, not a decision — it does not capture oxygenation trends, stable social support, drug interactions, or the trajectory of illness, and it should never be the sole basis for an admission or discharge. Many clinicians pair it with a fast bedside tool such as CURB-65.

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Questions

Frequently Asked Questions

6 questions

How is the PSI different from CURB-65?+

The Pneumonia Severity Index uses 20 variables to sort patients into five mortality classes and is especially good at identifying low-risk patients who can be treated as outpatients. CURB-65 uses only five items (confusion, urea, respiratory rate, blood pressure, and age 65 or older), so it is faster at the bedside but less granular. The PSI was derived and validated on a larger cohort and gives finer risk stratification, at the cost of needing labs and a chest x-ray.

What are the PSI risk class cutoffs?+

Class I is assigned by a screening step (age under 50 with no listed comorbidities or exam abnormalities), not by points. For everyone else the point total sets the class: Class II is 70 points or fewer, Class III is 71 to 90, Class IV is 91 to 130, and Class V is more than 130 points.

How does the score adjust for age and sex?+

Age is the largest single contributor. For men, the demographic points equal the age in years. For women, the points equal the age minus 10. That 10-point reduction reflects the lower age-adjusted pneumonia mortality observed in women in the original derivation cohort.

Why does nursing-home residence add points?+

Nursing-home residents had higher pneumonia mortality in the derivation study, so residence adds a fixed 10 points to the demographic base. Note that nursing-home residence does not count toward the Class I screening step — only age, the five comorbidities, and the five exam findings do.

What is the 30-day mortality for Class V?+

Class V, the highest-risk group (more than 130 points), had about 27% 30-day mortality in the original derivation cohort. These patients generally warrant inpatient admission and often ICU-level care, guided by the full clinical picture.

When should I use CURB-65 instead of the PSI?+

CURB-65 trades granularity for speed and needs no imaging, so it is convenient at the bedside before labs return. The PSI's 20 variables give finer stratification and are strongest at confirming who is safe for outpatient care, but require labs and a chest x-ray. Many clinicians screen with CURB-65 first and use the PSI once the full data set is available to support the admission decision.

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Patient Findings

Demographics

Comorbidities

Exam findings

Labs & imaging

PSI Points & Risk Class

Your Point Breakdown

Risk Class, Points & 30-Day Mortality

All Scored Items & Point Values

How to Use This Calculator

Enter age and sex

Check every finding that applies

Read the class and mortality, then check the tables

Formula & Methodology

Trust, Methodology & Sources

Key Terms Explained

Real-World Examples

Class I — low risk

Class III — borderline

Class V — high risk

Understanding the Pneumonia Severity Index (PORT Score)

How the PSI is scored

Risk Class I is a screening shortcut, not a low score

How it guides disposition and its limits

Frequently Asked Questions

Get a branded PDF of your results

Pneumonia Severity Index Calculator

Patient Findings

Demographics

Comorbidities

Exam findings

Labs & imaging

PSI Points & Risk Class

Your Point Breakdown

Risk Class, Points & 30-Day Mortality

All Scored Items & Point Values

How to Use This Calculator

Enter age and sex

Check every finding that applies

Read the class and mortality, then check the tables

Formula & Methodology

Trust, Methodology & Sources

Key Terms Explained

Real-World Examples

Understanding the Pneumonia Severity Index (PORT Score)

How the PSI is scored

Risk Class I is a screening shortcut, not a low score

How it guides disposition and its limits

Frequently Asked Questions

Get a branded PDF of your results

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