title: Marked reduction in 30-day mortality among elderly patients with community-acquired pneumonia.
abstract: BACKGROUND
  Community-acquired pneumonia is the most common infectious cause of death in the US. Over the last 2 decades, patient characteristics and clinical care have changed. To understand the impact of these changes, we quantified incidence and mortality trends among elderly adults.
  
  
  METHODS
  We used Medicare claims to identify episodes of pneumonia, based on a validated combination of diagnosis codes. Comorbidities were ascertained using the diagnosis codes located on a 1-year look back. Trends in patient characteristics and site of care were compared. The association between year of pneumonia episode and 30-day mortality was then evaluated by logistic regression, with adjustment for age, sex, and comorbidities.
  
  
  RESULTS
  We identified 2,654,955 cases of pneumonia from 1987-2005. During this period, the proportion treated as inpatients decreased, the proportion aged ≥80 years increased, and the frequency of many comorbidities rose. Adjusted incidence increased to 3096 episodes per 100,000 population in 1999, with some decrease thereafter. Age/sex-adjusted mortality decreased from 13.5% to 9.7%, a relative reduction of 28.1%. Compared with 1987, the risk of mortality decreased through 2005 (adjusted odds ratio, 0.46; 95% confidence interval, 0.44-0.47). This result was robust to a restriction on comorbid diagnoses assessing for the results' sensitivity to increased coding.
  
  
  CONCLUSIONS
  These findings show a marked mortality reduction over time in community-acquired pneumonia patients. We hypothesize that increased pneumococcal and influenza vaccination rates as well as wider use of guideline-concordant antibiotics explain a large portion of this trend.
authors.affiliation: Section of Hospital Medicine, University of Chicago, IL 60637, USA. gruhnke@medicine.bsd.uchicago.edu
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Ruhnke
authors.forename: Marcelo
authors.initials: M
authors.lastname: Coca-Perraillon
authors.forename: Barrett T
authors.initials: BT
authors.lastname: Kitch
authors.forename: David M
authors.initials: DM
authors.lastname: Cutler
mesh_terms: D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000890:Anti-Infective Agents / Q000627:therapeutic use; D017714:Community-Acquired Infections / Q000175:diagnosis / Q000401:mortality; D015897:Comorbidity; D048909:Diabetes Complications / Q000401:mortality; D005260:Female; D006333:Heart Failure / Q000401:mortality; D006801:Humans; D015994:Incidence; D007297:Inpatients / Q000706:statistics & numerical data; D007345:Insurance Claim Review; D016015:Logistic Models; D008297:Male; D006278:Medicare; D009026:Mortality / Q000639:trends; D016017:Odds Ratio; D010045:Outpatients / Q000706:statistics & numerical data; D022242:Pneumococcal Vaccines / Q000008:administration & dosage; D011014:Pneumonia / Q000175:diagnosis* / Q000188:drug therapy / Q000453:epidemiology / Q000401:mortality*; D012307:Risk Factors; D017678:Sex Distribution; D013296:Streptococcus pneumoniae / Q000302:isolation & purification; D014481:United States / Q000453:epidemiology
chemical_list: D000890:Anti-Infective Agents; D022242:Pneumococcal Vaccines