Prospective evaluation of pneumonia severity index in hospitalised patients with community-acquired pneumonia

Respir Med. 2004 Sep;98(9):872-8. doi: 10.1016/j.rmed.2004.02.022.


The aim of the present study was to investigate whether the pneumonia severity index (PSI) could adequately predict the severity of community-acquired pneumonia (CAP) and could be used as a severity of illness classification system. Furthermore, reasons that may influence the decision to admit low risk patients were analysed. In a prospective study 260 patients with CAP were included. Stratification in five risk classes according to the PSI was compared with parameters that are closely related to severity of CAR A significant difference in severity parameters, such as length of stay (P < 0.001) and simplified acute physiologic score and acute physiologic and chronic health evaluation II score (P < 0.001) was found between the five risk classes. Furthermore, a positive British Thoracic Society (BTS) rule and modified BTS rule score was significantly more prevalent in the higher risk classes (P < 0.001). The patient population had an average 30-day mortality of 10% and a mean Intensive Care Unit (ICU) admission rate of 8%. The mortality rate and ICU admission rate significantly differed between the five risk classes (P < 0.001), in which the highest ICU admission rate (40.9%) and the highest mortality percentage (40.9%) were both found in risk class V. Several clinical factors (n = 64), such as an exacerbation of chronic obstructive pulmonary disease in 17 patients and clinical appearance of being ill in 16 patients, lack of improvement on outpatient antibiotic therapy (n = 15) and social circumstances (n = 3) were reasons that influenced the decision to hospitalise low risk patients (n = 82). The results show that the PSI adequately predicted the severity of CAP and can be used as a severity of illness classification in CAP. Clinical and social factors other than those mentioned in the PSI have to be considered when making the decision to hospitalise patients with CAP.

MeSH terms

  • Age Distribution
  • Community-Acquired Infections / classification
  • Community-Acquired Infections / mortality
  • Critical Care
  • Female
  • Hospitalization
  • Humans
  • Male
  • Middle Aged
  • Pneumonia / classification*
  • Pneumonia / mortality
  • Prognosis
  • Prospective Studies
  • Risk Assessment / methods
  • Risk Factors
  • Severity of Illness Index*
  • Treatment Outcome