title: Comparing invasive and noninvasive management strategies for acute myocardial infarction using administrative databases.
abstract: OBJECTIVE
  The aim of this study was to compare outcomes after acute myocardial infarction between regions with low and high catheterization access.
  
  
  METHODS
  Observational study using administrative databases of patients with acute myocardial infarction in provinces with low (Ontario) and high (Quebec and British Colombia) access to invasive cardiac procedures (ICP, n = 141718). Using instrumental variables to control for confounding, effectiveness of treatment was measured on 1-year mortality among marginal patients (patients for whom treatment is discretionary and highly dependent on access to ICP).
  
  
  RESULTS
  The ICP approach was associated with overall decreased mortality (-11%, 95% CI -13% to -8%) with statistically significant reductions in low-access regions (-16%, 95% CI -21% to -10%). High-access regions (QC -8%, 95% CI -19% to 4%) (BC -2%, 95% CI -12% to 7%) exhibited smaller marginal benefits.
  
  
  CONCLUSIONS
  The invasive approach benefits all marginal patients, with greater benefits in regions of lower access, indicating a threshold of availability above which further mortality benefits are negligible.
authors: Division of Clinical Epidemiology, McGill University Health Centre, Montreal, Quebec, Canada. louise.pilote@mcgill.ca
authors: Louise
authors: L
authors: Pilote
authors: Christine A
authors: CA
authors: Beck
authors: Mark J
authors: MJ
authors: Eisenberg
authors: Karin
authors: K
authors: Humphries
authors: Lawrence
authors: L
authors: Joseph
authors: John R
authors: JR
authors: Penrod
authors: Jack V
authors: JV
authors: Tu
mesh_terms: D015906:Angioplasty, Balloon, Coronary / Q000706:statistics & numerical data*; D001955:British Columbia; D006328:Cardiac Catheterization / Q000706:statistics & numerical data*; D003628:Database Management Systems; D005260:Female; D005500:Follow-Up Studies; D006302:Health Services Research; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D009203:Myocardial Infarction / Q000175:diagnosis / Q000401:mortality* / Q000628:therapy*; D009864:Ontario; D011792:Quebec; D012042:Registries; D012044:Regression Analysis; D018570:Risk Assessment; D016019:Survival Analysis; D015912:Thrombolytic Therapy / Q000706:statistics & numerical data*; D013997:Time Factors; D016896:Treatment Outcome