Pneumonia Severity Index: a validation and assessment study for its use as a triage tool in the emergency department

Introduction

Our rural 10-bed ICU serves a 167-bed hospital situated in a small town at the centre of the Australian Continent. The hospital is utilised mainly by Indigenous patients. We were interested to estimate the Pneumonia Severity Index (PSI) among all patients presenting to our emergency department (ED) with community-acquired pneumonia (CAP) during 2006 to ascertain whether this scoring system could be validated among our unique patient population and to ascertain whether the score could have been helpful to support a clinical decision to transfer patients to the medical ward or ICU.

Methods

All patients presenting to the ED during 2006 were identified and their demographic and parameters details noted to calculate their PSI scores, which were performed retrospectively. Triage was performed clinically by the ED doctors. The following complications were noted: requirement for artificial ventilation, septic shock, acute renal failure, requirement for percutaneous tracheostomy and mortality. All patients transferred to tertiary centres because of staff or bed shortages were also noted. Microbiological data were collected on all ICU patients and most of the ward patients.

Results

Four hundred and seventy-six CAP patients presented to the ED in 2006, of which 91% (436/476) were Indigenous and 12% (57/476) were transferred to the ICU. Admission characteristics of ICU patients revealed high incidences of alcoholism (76%) and chronic illness (70%). Artificial ventilation rates of these 57 patients were defined according to PSI severity: no patient with a score <91 required artificial ventilation, whereas 64% of patients with a score of 91–130 and 75% of patients with a score >130 required artificial ventilation. Using PSI < 91 for predicting absence of the need for artificial ventilation, specificity of 100% and sensitivity of 91% were demonstrated.

Conclusion

The CAP rate among the central Australian Indigenous population is unacceptably high. This high rate is associated with high incidences of alcoholism, chronic ill health and poor social conditions. The PSI has been validated in this study, accurately predicting mortality and the need for artificial ventilation. The PSI could be a useful tool to support a clinical decision to transfer patients from the ED to the general medical wards (PSI < 91) or to the ICU (PSI ≥ 91).