title: A validation and potential modification of the pneumonia severity index in elderly patients with community-acquired pneumonia.
abstract: OBJECTIVE
  To evaluate the discriminatory power of the Pneumonia Severity Index (PSI) in elderly patients with community-acquired pneumonia (CAP) and to improve its performance.
  
  
  METHODS
  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.
  
  
  METHODS
  Iwata City Hospital, a 400-bed general hospital.
  
  
  METHODS
  Patients aged 80 and older who had CAP and were admitted to the hospital.
  
  
  METHODS
  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%).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Internal Medicine, Second Division, Hamamatsu University School of Medicine, Hamamatsu, Japan.
authors.forename: Tateaki
authors.initials: T
authors.lastname: Naito
authors.forename: Takafumi
authors.initials: T
authors.lastname: Suda
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Yasuda
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamada
authors.forename: Akihito
authors.initials: A
authors.lastname: Todate
authors.forename: Tomoyoshi
authors.initials: T
authors.lastname: Tsuchiya
authors.forename: Jun
authors.initials: J
authors.lastname: Sato
authors.forename: Kingo
authors.initials: K
authors.lastname: Chida
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Nakamura
mesh_terms: D000369:Aged, 80 and over; D017714:Community-Acquired Infections / Q000175:diagnosis / Q000401:mortality*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D018410:Pneumonia, Bacterial / Q000175:diagnosis / Q000401:mortality*; D011379:Prognosis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D015996:Survival Rate / Q000639:trends