PSI - Pneumonia Severity of Illness Scoring System
| Patient Characteristic | Points assigned | |
| Demographic factors | Age: Males | age (in yrs) |
| Females | age (in yrs) -10 | |
| Nursing home resident | +10 | |
| Comorbid illnesses | Neoplastic disease (active) | +30 |
| Chronic liver disease | +20 | |
| Congestive heart failure | +10 | |
| Cerebrovascular disease | +10 | |
| Chronic renal disease | +10 | |
| Physical examination findings | Altered mental status | +20 |
| Respiratory rate (RR) ≥30/minute | +20 | |
| Systolic blood pressure (BP) <90 mmHg | +20 | |
| Temperature (T) <35°C or ≥40°C | +15 | |
| Pulse (P) ≥125/minute | +10 | |
| Laboratory and radiographic findings | pH <7.35 | +30 |
| Urea ≥11mmol/L or creatinine ≥120umol/L | +20 | |
| Sodium <130mmol/L | +20 | |
| Glucose ≥14mmol/L | +10 | |
| Hematocrit <30% | +10 | |
| PO2 <60mmHg or 02 sat <90% | +10 | |
| Pleural effusion on chest xray | +10 |
| Risk Class | # of Points | Mortality (%) | Recommendations for Site of Care |
| I | ≤50 yrs old with no comorbidities or listed abnormal physical findings | 0.1 | Outpatient |
| II | 0-70 points | 0.6 | Outpatient |
| III | 71-90 points | 0.9 | Generally outpatient |
| IV | 91-130 points | 9.3 | Inpatient |
| V | >130 points | 27.0 | Inpatient |
Reprinted from Fine MJ, Auble TE, Yealy DM, et al. A prediction rule to identify low-risk patients with community-acquired pneumonia. N Engl J Med 1997; 336: 243-50
| CAP severity | PSI |
| Mild | I or II |
| Moderate | III |
| Severe | IV or V |