title: A self-controlled case series to assess the effectiveness of beta blockers for heart failure in reducing hospitalisations in the elderly.
abstract: BACKGROUND
  To determine the suitability of using the self-controlled case series design to assess improvements in health outcomes using the effectiveness of beta blockers for heart failure in reducing hospitalisations as the example.
  
  
  METHODS
  The Australian Government Department of Veterans' Affairs administrative claims database was used to undertake a self-controlled case-series in elderly patients aged 65 years or over to compare the risk of a heart failure hospitalisation during periods of being exposed and unexposed to a beta blocker. Two studies, the first using a one year period and the second using a four year period were undertaken to determine if the estimates varied due to changes in severity of heart failure over time.
  
  
  RESULTS
  In the one year period, 3,450 patients and in the four year period, 12, 682 patients had at least one hospitalisation for heart failure. The one year period showed a non-significant decrease in hospitalisations for heart failure 4-8 months after starting beta-blockers, (RR, 0.76; 95% CI (0.57-1.02)) and a significant decrease in the 8-12 months post-initiation of a beta blocker for heart failure (RR, 0.62; 95% CI (0.39, 0.99)). For the four year study there was an increased risk of hospitalisation less than eight months post-initiation and significant but smaller decrease in the 8-12 month window (RR, 0.90; 95% CI (0.82, 0.98)).
  
  
  CONCLUSIONS
  The results of the one year observation period are similar to those observed in randomised clinical trials indicating that the self-controlled case-series method can be successfully applied to assess health outcomes. However, the result appears sensitive to the study periods used and further research to understand the appropriate applications of this method in pharmacoepidemiology is still required. The results also illustrate the benefits of extending beta blocker utilisation to the older age group of heart failure patients in which their use is common but the evidence is sparse.
authors.affiliation: Data Management and Analysis Centre, Discipline of Public Health, University of Adelaide, South Australia, 5000, Australia. emmae.ramsay@adelaide.edu.au
authors.forename: Emmae N
authors.initials: EN
authors.lastname: Ramsay
authors.forename: Elizabeth E
authors.initials: EE
authors.lastname: Roughead
authors.forename: Ben
authors.initials: B
authors.lastname: Ewald
authors.forename: Nicole L
authors.initials: NL
authors.lastname: Pratt
authors.forename: Philip
authors.initials: P
authors.lastname: Ryan
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000368:Aged; D000369:Aged, 80 and over; D002986:Clinical Trials as Topic; D005500:Follow-Up Studies; D006333:Heart Failure / Q000188:drug therapy*; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D012107:Research Design; D016896:Treatment Outcome
chemical_list: D000319:Adrenergic beta-Antagonists