title: Time dependent effect on mortality of drug-eluting stents versus bare metal stents.
abstract: OBJECTIVE
  The comparison of all-cause long-term mortality between the use of drug-eluting stents versus bare metal stents in patients treated with percutaneous coronary interventions.
  
  
  METHODS
  Observational data from patients treated at Feiring Heart Clinic from 1999 until 2010 with a follow-up of survival at March 8, 2011. The survival was compared using Cox regression with ordinary covariates, propensity score used as covariate and 1:1 propensity score matching.
  
  
  RESULTS
  The analyses included 5690 patients treated solely with bare metal stents and 2916 with drug-eluting stents. During the study period (October 2002 to March 2011), 996 deaths were observed. Due to nonproportional hazard effect on mortality of drug-eluting stents compared to bare metal stents, a landmark analysis splitting time at 9 months was employed. All analyses indicated a significantly reduced mortality by drug-eluting stents in the first 9 months with hazard ratios ranging from 0.42 to 0.51 with no difference in mortality from 9 months to 8 years of follow-up.
  
  
  CONCLUSIONS
  Short-term mortality was significantly reduced in the drug-eluting stent group compared to the bare metal stent group. A selection bias could not be ruled out as an explanation for this effect. No difference was observed in mortality after 9 months.
authors.affiliation: Feiring Heart Clinic, Norway. moelsta@online.no
authors.forename: Per
authors.initials: P
authors.lastname: Mølstad
mesh_terms: D000368:Aged; D015906:Angioplasty, Balloon, Coronary; D016001:Confidence Intervals; D003324:Coronary Artery Disease / Q000188:drug therapy / Q000401:mortality* / Q000628:therapy; D054855:Drug-Eluting Stents; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009026:Mortality / Q000639:trends*; D015999:Multivariate Analysis; D009664:Norway; D057216:Propensity Score; D016016:Proportional Hazards Models; D012042:Registries; D018709:Statistics, Nonparametric; D016019:Survival Analysis; D013997:Time Factors