A validation and potential modification of the pneumonia severity index in elderly patients with community-acquired pneumonia

J Am Geriatr Soc. 2006 Aug;54(8):1212-9. doi: 10.1111/j.1532-5415.2006.00825.x.


Objectives: To evaluate the discriminatory power of the Pneumonia Severity Index (PSI) in elderly patients with community-acquired pneumonia (CAP) and to improve its performance.

Design: Retrospective review of 193 patients from 1999 to 2001 to derive prognostic rules. The rules were prospectively validated in 144 patients from 2002 to 2003.

Setting: Iwata City Hospital, a 400-bed general hospital.

Participants: Patients aged 80 and older who had CAP and were admitted to the hospital.

Measurements: Predictors of 30-day mortality were identified using logistic regression analysis, and several rules were constructed by combining the PSI and the independent predictors.

Results: The original PSI, which defines PSI Class IV and V as a high-risk group, did not perform well in discriminating survivors from nonsurvivors (sensitivity 100%, specificity 15%), whereas a modified PSI, which defines only PSI Class V as a high-risk group, performed better (sensitivity 86%, specificity 63%). Three predictors for mortality were identified independent from the modified PSI: performance status (PS) Grade 3 or higher, anorexia, and partial pressure of carbon dioxide of 50 mmHg or greater. By combining the modified PSI and PS, the performance could be further improved (sensitivity 79%, specificity 80%).

Conclusion: The modified PSI could identify low-risk patients more accurately than the original PSI. In addition, by combining the modified PSI with PS, higher performance was obtained. Such information would aid physicians in clinical decision-making without overestimating the risk for elderly patients with CAP.

Publication types

  • Comparative Study
  • Validation Study

MeSH terms

  • Aged, 80 and over
  • Community-Acquired Infections / diagnosis
  • Community-Acquired Infections / mortality*
  • Female
  • Follow-Up Studies
  • Humans
  • Japan / epidemiology
  • Male
  • Pneumonia, Bacterial / diagnosis
  • Pneumonia, Bacterial / mortality*
  • Prognosis
  • Retrospective Studies
  • Severity of Illness Index
  • Survival Rate / trends