Acute Severity of Illness • PBS (Chow & Yu 1999)
Clinical Evaluation
Mortality Risk Score
0
Non-Critically Ill
Lower short-term mortality risk. Focus on appropriate antimicrobial therapy and source control.
qPitt Equivalent: Negative
Guidelines & Evidence
Verified
Last Review: 2026-07-17
When to Use
Clinical Utility
Bedside mortality risk stratification for patients with bloodstream infections (BSIs).
Validating clinical severity in carbapenem-resistant Enterobacteriaceae (CRE) infections (Henderson et al. 2020).
Immediate triage without laboratory results (unlike APACHE or SOFA).
Classification of patients as "Critically Ill" (PBS ≥4) vs "Non-Critically Ill" (PBS <4).
Expanding Use Cases
While originally designed for bacteremia, recent evidence confirms PBS is just as predictive in non-bacteremic infections (Pneumonia, cUTI) caused by multidrug-resistant organisms.
How it Works
The 5 Clinical Variables
| Mental Status | Normal (0), Disoriented (1), Stupor (2), Coma (4) |
| Temperature | 35.1-36°C or 39-39.9°C (+1) | ≤35°C or ≥40°C (+2) |
| Hypotension | Drop in SBP >30mmHg, DBP >20mmHg, or Vasopressors (+2) |
| Mech. Ventilation | Acute requirement for respiratory support (+2) |
| Cardiac Arrest | Occurring within 48 hours of initial culture (+4) |
The qPitt (Quick Pitt)
A binary version (Score 0–5). A qPitt ≥2 provides similar discrimination to a PBS ≥4. It removes the complex temperature weighting and focuses on the high-yield indicators: Hypotension, Mech Vent, Cardiac Arrest, Altered Mental Status, and Hypothermia (<36°C).
Clinical Pearls
Resilience vs. Laboratory Scores
The Fever Paradox
While high fever (≥40°C) is included in the classical PBS, hypothermia (<36°C) is actually a stronger independent predictor of early mortality in septic populations.
The Evidence
Key Literature
The Pitt Bacteremia Score Predicts Mortality in Nonbacteremic Infections.
Henderson H et al. • Clin Infect Dis.. 2020;n=475. Validated that a PBS ≥4 predicts mortality with high discrimination (c-statistic 0.85) regardless of culture source.
Resilience of the Pitt Bacteremia Score: 3 Decades and Counting.
Al-Hasan MN et al. • Clin Infect Dis.. 2020;Clinical commentary on the PBS as a unmatched matching and stratification tool in ID research.
Combination antibiotic therapy versus monotherapy for Gram-negative bacteraemia.
Chow JW et al. • Int J Antimicrob Agents.. 1999;The established version of the score weighting used in modern practice.
Resources
Direct Study Access
Last Comprehensive Review: 2026-07-17