Pneumonia Severity Assessment

Overview

Calculate pneumonia severity scores from FHIR Patient, Observation, and Condition resources using CURB-65, PSI/PORT Score (Pneumonia Severity Index), and A-DROP criteria. Differentiate community-acquired pneumonia (CAP) from hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP). Generate disposition recommendations (outpatient, observation, inpatient, ICU) and empiric antibiotic guidance based on severity level and guidelines. Create a ClinicalImpression resource documenting findings.

FHIR Resources Used

Resource	Purpose	Key Fields
Patient	Age, gender, nursing home residence	birthDate, gender, address
Condition	Comorbidities, pneumonia type, pleural effusion	code, clinicalStatus, onsetDateTime
Observation	Vitals (BP, HR, RR, temp, SpO2), labs (BUN, glucose, Na, Hct, PaO2, pH)	code, valueQuantity, effectiveDateTime
Encounter	Admission source, current encounter type	class, period, hospitalization
MedicationRequest	Current antibiotics, immunosuppressants	medicationCodeableConcept, status
ClinicalImpression	Output: severity assessment	status, description, finding

Instructions

Step 1: Retrieve Patient Demographics

code

Tool: fhir_read
resourceType: "Patient"
id: "[patient-id]"

Extract age (exact years), gender (male = additional PSI points). Check address for nursing home/long-term care facility (affects CAP vs HCAP classification).

Step 2: Determine CAP vs HAP/VAP

code

Tool: fhir_search
resourceType: "Encounter"
queryParams: "patient=[patient-id]&status=in-progress"

Classification logic:

•CAP: Pneumonia onset before or within 48 hours of hospital admission. Includes nursing home patients (previously "HCAP" -- per 2019 ATS/IDSA guidelines, HCAP category eliminated; treat as CAP unless HAP/VAP risk factors present).
•HAP: Pneumonia onset >=48 hours after hospital admission, not intubated at time of onset.
•VAP: Pneumonia onset >=48 hours after endotracheal intubation.

Check Encounter.period.start against pneumonia Condition.onsetDateTime. Check for active Procedure with SNOMED 40617009 (mechanical ventilation).

Step 3: Retrieve Active Conditions and Comorbidities

code

Tool: fhir_search
resourceType: "Condition"
queryParams: "patient=[patient-id]&clinical-status=active,recurrence,remission"

PSI-relevant conditions (SNOMED codes):

•363346000: Neoplastic disease (malignancy)
•235856003: Hepatic disease (liver disease)
•42343007: Congestive heart failure
•230690007: Cerebrovascular disease
•709044004: Chronic kidney disease / renal disease
•233604007: Pneumonia (the current diagnosis)
•60046008: Pleural effusion

Also search for pleural effusion specifically:

code

Tool: fhir_search
resourceType: "Condition"
queryParams: "patient=[patient-id]&code=60046008"

Step 4: Retrieve Vital Signs

Respiratory Rate:

code

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=9279-1&_sort=-date&_count=3"

LOINC 9279-1. CURB-65: >=30. PSI: >=30. A-DROP: >=30.

Systolic Blood Pressure:

code

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=8480-6&_sort=-date&_count=3"

LOINC 8480-6. CURB-65: SBP <90 or DBP <=60. PSI: SBP <90.

Diastolic Blood Pressure:

code

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=8462-4&_sort=-date&_count=3"

LOINC 8462-4. CURB-65: DBP <=60.

Heart Rate:

code

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=8867-4&_sort=-date&_count=3"

LOINC 8867-4. PSI: >=125. A-DROP does not use HR directly.

Temperature:

code

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=8310-5&_sort=-date&_count=3"

LOINC 8310-5. PSI: <35C or >=40C.

SpO2:

code

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=2708-6&_sort=-date&_count=3"

LOINC 2708-6. A-DROP: SpO2 <=90% or PaO2 <=60 mmHg. ATS/IDSA severe CAP criterion.

Step 5: Retrieve Laboratory Values

BUN (Blood Urea Nitrogen):

code

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=3094-0&_sort=-date&_count=1"

LOINC 3094-0. CURB-65: BUN >20 mg/dL (>7 mmol/L). PSI: BUN >=30 mg/dL. A-DROP: BUN >=21 mg/dL.

Serum Sodium:

code

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=2951-2&_sort=-date&_count=1"

LOINC 2951-2. PSI: Na <130 mEq/L.

Serum Glucose:

code

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=2345-7&_sort=-date&_count=1"

LOINC 2345-7. PSI: glucose >=250 mg/dL.

Hematocrit:

code

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=4544-3&_sort=-date&_count=1"

LOINC 4544-3. PSI: Hct <30%.

Arterial pH:

code

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=2744-1&_sort=-date&_count=1"

LOINC 2744-1. PSI: pH <7.35.

PaO2:

code

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=2703-7&_sort=-date&_count=1"

LOINC 2703-7. PSI: PaO2 <60 mmHg. A-DROP: PaO2 <=60 mmHg.

Step 6: Assess Mental Status

Search for documented confusion or altered mental status:

code

Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=9269-2&_sort=-date&_count=1"

LOINC 9269-2 = GCS total. Also check for documented Condition of confusion (SNOMED 130987000) or altered mental status (SNOMED 419284004).

CURB-65: new mental confusion (defined as AMT <=8 or new disorientation to person, place, or time). PSI: altered mental status (disorientation, stupor, coma). A-DROP: confusion (new onset).

Step 7: Calculate Scores

Refer to references/pneumonia-scoring.md for complete criteria.

CURB-65 (Score 0-5):

•C: Confusion (new onset)
•U: Urea (BUN) >20 mg/dL (>7 mmol/L)
•R: Respiratory rate >=30
•B: Blood pressure SBP <90 or DBP <=60
•65: Age >=65

PSI/PORT Score: Demographics + comorbidities + exam findings + labs = point total mapped to Risk Class I-V.

A-DROP (Score 0-5):

•A: Age (male >=70, female >=75)
•D: Dehydration (BUN >=21 mg/dL)
•R: Respiration (SpO2 <=90% or PaO2 <=60 mmHg)
•O: Orientation (confusion)
•P: Pressure (SBP <=90 mmHg)

Step 8: Evaluate ATS/IDSA Severe CAP Criteria

Check for major criteria (either = ICU admission):

•Septic shock requiring vasopressors
•Respiratory failure requiring mechanical ventilation

Check for minor criteria (>=3 = ICU admission):

•RR >= 30
•PaO2/FiO2 <= 250
•Multilobar infiltrates
•Confusion/disorientation
•BUN >= 20 mg/dL
•WBC < 4,000
•Platelets < 100,000
•Temperature < 36C
•Hypotension requiring aggressive fluid resuscitation

Step 9: Create ClinicalImpression Resource

code

Tool: fhir_create
resourceType: "ClinicalImpression"
resource: {
  "resourceType": "ClinicalImpression",
  "status": "completed",
  "subject": {"reference": "Patient/[patient-id]"},
  "effectiveDateTime": "[current-datetime]",
  "description": "Pneumonia severity: CURB-65 [X]/5, PSI Class [I-V] ([X] pts), A-DROP [X]/5. Type: [CAP/HAP/VAP].",
  "finding": [
    {
      "itemCodeableConcept": {
        "coding": [{"system": "http://snomed.info/sct", "code": "233604007", "display": "Pneumonia"}],
        "text": "Pneumonia type: [CAP/HAP/VAP]. Severity: [MILD/MODERATE/SEVERE]. Disposition: [outpatient/observation/inpatient/ICU]."
      }
    }
  ],
  "note": [{"text": "Recommended empiric therapy: [antibiotic regimen]. ATS/IDSA severe criteria: [X] minor criteria met."}]
}

Step 10: Format Output

code

PNEUMONIA SEVERITY ASSESSMENT
==============================
Patient: [name] | Age: [age] | Sex: [sex]
Assessment Date: [datetime]
Pneumonia Type: [CAP / HAP / VAP]

SCORES
------
CURB-65:  [X]/5  - [disposition recommendation]
  C (Confusion): [Y/N]
  U (BUN >20): [Y/N] ([value])
  R (RR >=30): [Y/N] ([value])
  B (BP low): [Y/N] (SBP [value], DBP [value])
  65 (Age >=65): [Y/N]

PSI/PORT: Class [I-V] ([X] points) - [mortality risk]
  Demographics: [points breakdown]
  Comorbidities: [points breakdown]
  Exam: [points breakdown]
  Labs: [points breakdown]

A-DROP:   [X]/5  - [severity level]

ATS/IDSA SEVERE CAP CRITERIA
-----------------------------
Major criteria: [X]/2  Minor criteria: [X]/9
ICU recommended: [YES/NO]

DISPOSITION RECOMMENDATION
--------------------------
[Outpatient / Observation / General ward / ICU]
Rationale: [based on scoring concordance]

EMPIRIC ANTIBIOTIC RECOMMENDATION
----------------------------------
[Regimen based on severity, setting, and risk factors]

Examples

Example 1: Moderate Severity CAP

User says: "Score pneumonia severity for patient 22334"

Actions:

•fhir_read Patient/22334 -- 72M
•fhir_search Encounter -- admitted 6 hours ago via ED
•fhir_search Condition -- CAP, COPD, diabetes. No liver/renal/heart failure/cancer.
•fhir_search Observation vitals -- RR 24, SBP 105, DBP 62, HR 98, Temp 38.9C, SpO2 93%
•fhir_search Observation labs -- BUN 28, Na 136, Glucose 210, Hct 38%, pH 7.38, PaO2 65
•Mental status: oriented, no confusion
•Calculate: CURB-65 = 2 (BUN >20 = 1, Age >=65 = 1), PSI = 102 (age 72 + male 0 adjustment... age 72, COPD +10, DM +10, BUN >=30 not met at 28, actually BUN <30 = 0 for PSI... recalculate: age 72, COPD +10, DM +10 = 92 base + exam/lab points), A-DROP = 2 (Age M>=70, BUN >=21)
•ATS/IDSA: 0 major, 1 minor (BUN >=20)

Result:

code

PNEUMONIA SEVERITY ASSESSMENT
==============================
Patient: Harold Kim | Age: 72 | Sex: Male
Pneumonia Type: CAP (admitted via ED, onset pre-admission)

SCORES
------
CURB-65:  2/5  - Consider hospital admission (short stay or observation)
PSI/PORT: Class IV (92 points) - Mortality 8.2%
A-DROP:   2/5  - Moderate severity

ATS/IDSA SEVERE CAP CRITERIA
-----------------------------
Major criteria: 0/2  Minor criteria: 1/9
ICU recommended: NO

DISPOSITION RECOMMENDATION
--------------------------
General ward admission (medical floor with telemetry)
Rationale: CURB-65 2 supports admission. PSI Class IV supports inpatient. No ICU criteria met. SpO2 93% requires supplemental O2.

EMPIRIC ANTIBIOTIC RECOMMENDATION
----------------------------------
Non-severe inpatient CAP (no Pseudomonas risk):
- Ceftriaxone 2g IV daily + Azithromycin 500mg IV daily
- OR Respiratory fluoroquinolone: Levofloxacin 750mg IV daily (if beta-lactam allergy)
- Reassess at 48-72 hours for clinical improvement and step-down to oral.

Example 2: Severe CAP Requiring ICU

User says: "CURB-65 and PORT score for patient 88776, she's in the ED with bad pneumonia"

Actions:

•fhir_read Patient/88776 -- 68F
•fhir_search Condition -- CAP (multilobar), CHF, CKD stage 3
•fhir_search Observation vitals -- RR 34, SBP 78, DBP 45, HR 122, Temp 35.2C, SpO2 84%
•fhir_search Observation labs -- BUN 42, Na 128, Glucose 180, Hct 28%, pH 7.28, PaO2 52
•Mental status: confused, disoriented
•Calculate: CURB-65 = 5/5, PSI Class V (>130 pts), A-DROP = 5/5
•ATS/IDSA: 0 major (not yet intubated/on vasopressors), 7 minor (RR >=30, PaO2/FiO2 <250, multilobar, confusion, BUN >=20, Plt check, Temp <36)

Result:

code

SCORES
------
CURB-65:  5/5  - HIGH RISK (mortality ~57%, ICU admission)
PSI/PORT: Class V (168 points) - Mortality 27-31%
A-DROP:   5/5  - EXTREMELY SEVERE

ATS/IDSA SEVERE CAP CRITERIA
-----------------------------
Major criteria: 0/2  Minor criteria: 7/9
ICU recommended: YES (>=3 minor criteria met)

DISPOSITION RECOMMENDATION
--------------------------
ICU ADMISSION
Rationale: All scores at maximum severity. 7 ATS/IDSA minor criteria met. Impending respiratory failure (SpO2 84%, PaO2 52). Hemodynamically unstable (SBP 78). Prepare for possible intubation and vasopressors.

EMPIRIC ANTIBIOTIC RECOMMENDATION
----------------------------------
Severe CAP, ICU admission:
- Ceftriaxone 2g IV daily + Azithromycin 500mg IV daily + Vancomycin 25mg/kg IV (MRSA coverage given severity)
- If Pseudomonas risk: Piperacillin-tazobactam 4.5g IV q6h + Levofloxacin 750mg IV daily
- Obtain sputum culture, blood cultures x2, Legionella/Pneumococcal urinary antigens before antibiotics if possible.

Troubleshooting

BUN Available Only as Urea (Non-US Systems)

•
Some FHIR servers report urea in mmol/L (LOINC 3091-6) instead of BUN in mg/dL (LOINC 3094-0). Conversion: BUN (mg/dL) = Urea (mmol/L) x 2.8. CURB-65 threshold: BUN >20 mg/dL = Urea >7 mmol/L. Search both:
code
```
Tool: fhir_search
resourceType: "Observation"
queryParams: "patient=[patient-id]&code=3094-0,3091-6&_sort=-date&_count=1"
```

Arterial Blood Gas Not Available

•If PaO2 and pH are unavailable (no ABG drawn), use SpO2 as surrogate for oxygenation assessment. SpO2 <=90% on room air approximates PaO2 <=60 mmHg. Note "ABG not available -- oxygenation assessed by SpO2 only" in output. pH component of PSI cannot be scored without ABG -- note as "pH unavailable, PSI score may underestimate severity."

Nursing Home Status Not in Patient Resource

•Check Patient.address for long-term care facility indicators. Also check Encounter.hospitalization.origin for transfer from skilled nursing facility. If unclear, flag "Nursing home/LTCF status unknown -- assumed community-dwelling for scoring purposes."

Related Skills

•sepsis-screening -- pneumonia is a leading cause of sepsis; run sepsis screening if CURB-65 >=3 or hemodynamic instability
•clinical-summary-generator -- for full patient context
•medication-reconciliation -- to verify current antibiotic therapy and potential interactions