title: Risk stratification for cardiac complications in patients hospitalized for community-acquired pneumonia.
abstract: OBJECTIVE
  To derive and validate a clinical rule that stratifies the risk of cardiac complications in patients hospitalized for community-acquired pneumonia (CAP) and compare its performance to the pneumonia severity index (PSI) score.
  
  
  METHODS
  Two cohorts of patients hospitalized for CAP were selected for the study. We used regression techniques in the derivation cohort (1343 patients enrolled in the Pneumonia Patient Outcomes Research Team study between October 1991 and March 1994) to generate a prediction rule that we validated in the validation cohort (608 patients enrolled in the Dissemination of Guidelines for Length of Stay study between February 1998 and March 1999). Discrimination and reclassification analyses compared its performance against the PSI score.
  
  
  RESULTS
  A prediction model for cardiac complications in the derivation cohort included age, 3 preexisting conditions, 2 vital signs, and 7 common laboratory or radiographic parameters. Discrimination (C statistic, 0.81; 95% CI, 0.78-0.84) and calibration (Hosmer-Lemeshow goodness-of-fit test, χ(2)=13.0; P=.11) were good. We derived a point score system from this model that when applied to the validation cohort also had good discrimination (C statistic, 0.78; 95% CI, 0.74-0.83) and calibration (Hosmer-Lemeshow, χ(2)=9.0; P=.34). On the basis of this score, we defined 4 categories of incremental risk of cardiac complications. The incidence of cardiac complications across risk categories increased linearly (from lowest to highest) in both the derivation (3.0%, 17.8%, 35.2%, and 72.2%) and validation (5.0%, 8.2%, 28.3%, and 48.9%) cohorts (Cochran-Armitage linear trend test, P<.01). The new score outperformed the PSI score in predicting cardiac complications in the validation cohort (C statistic, 0.78 vs 0.74; P=.03; proportion of patients correctly reclassified by the new score, 44%).
  
  
  CONCLUSIONS
  We derived and validated a clinical rule that accurately stratifies the risk of cardiac complications in patients hospitalized for CAP.
authors.affiliation: Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada; Ottawa Hospital Research Institute, Ottawa, Ontario, Canada. Electronic address: vcorrales@toh.on.ca.
authors.forename: Vicente F
authors.initials: VF
authors.lastname: Corrales-Medina
authors.affiliation: Department of Epidemiology and Community Medicine, University of Ottawa, Ottawa, Ontario, Canada; Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.
authors.forename: Monica
authors.initials: M
authors.lastname: Taljaard
authors.affiliation: Division of General Internal Medicine, Department of Medicine, University of Pittsburgh, and Center for Health Equity Research and Promotion, VA Pittsburgh Healthcare System, Pittsburgh, PA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Fine
authors.affiliation: Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada; University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
authors.forename: Girish
authors.initials: G
authors.lastname: Dwivedi
authors.affiliation: Department of Emergency Medicine, University of Ottawa, Ottawa, Ontario, Canada; Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Perry
authors.affiliation: Department of Medicine and Department of Molecular Virology and Microbiology, Baylor College of Medicine, and Medical Care Line (Infectious Disease Section), Michael E. DeBakey VA Medical Center, Houston, TX.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Musher
authors.affiliation: Division of Cardiology, University of Pennsylvania, and Philadelphia VA Medical Center, Philadelphia, PA.
authors.forename: Julio A
authors.initials: JA
authors.lastname: Chirinos
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002170:Canada; D015331:Cohort Studies; D017714:Community-Acquired Infections / Q000453:epidemiology*; D015897:Comorbidity; D003627:Data Interpretation, Statistical; D005260:Female; D005544:Forecasting; D006331:Heart Diseases / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D011014:Pneumonia / Q000453:epidemiology*; D011446:Prospective Studies; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012720:Severity of Illness Index; D014481:United States
keywords: CAP; IDI; NRI; PSI; Pneumonia Severity Index; community-acquired pneumonia; integrated discrimination improvement; net reclassification improvement