title: Determinants of pre-hospital pharmacological intervention and its association with outcome in acute myocardial infarction.
abstract: BACKGROUND
  The aim of this study was a) To identify predictors of the use of aspirin in the pre-hospital setting in acute myocardial infarction (AMI) and b) To analyze whether the use of any of the recommended medications was associated with outcome.
  
  
  METHODS
  All patients with a final diagnosis of AMI, transported by the Emergency Medical Services (EMS) and admitted to the coronary care unit at Sahlgrenska University Hospital in Gothenburg, Sweden, in 2009-2011, were included.
  
  
  RESULTS
  1,726 patients were included. 58 % received aspirin by the EMS. Ischemic heart disease (IHD) was suspected in 84 %. Among patients who did not receive aspirin IHD was still suspected in 67 %. Among patients in whom IHD was suspected, and who were not on chronic treatment with aspirin the following predicted its pre-hospital use: a) age (odds ratio 0.98; 95 % confidence interval (CI) 0.96-0.99); b) a history of myocardial infarction (2.21; 1.21-4.04); c) priority given by EMS (8.07; 5.42-12.02); d) ST-elevation on ECG on admission to hospital (2.22; 1.50-3.29); e) oxygen saturation > 90 % (3.37; 1.81-6.27). After adjusting for confounders among patients who were not on chronic aspirin, only nitroglycerin of the recommended medications was associated with a reduced risk of death within 1 year (hazard ratio 0.40; 95 % CI 0.23-0.70).
  
  
  CONCLUSIONS
  Less than six out of ten patients with AMI received pre-hospital aspirin. Five clinical factors were independently associated with the pre-hospital administration of aspirin. This suggests that the decision to treat is multifactorial, and it highlights the lack of accurate diagnostic tools in the pre-hospital environment. Nitroglycerin was independently associated with a reduced risk of death, suggesting that we select the use for a low-risk cohort.
authors.affiliation: Department of Metabolism and Cardiovascular Research, Institute of Internal Medicine, Sahlgrenska University Hospital, Johan Herlitz office, Registercentrum i Västra Götaland, 413 45, Gothenburg, Sweden. rasmus.strandmark@gmail.com.
authors.forename: Rasmus
authors.initials: R
authors.lastname: Strandmark
authors.affiliation: Department of Metabolism and Cardiovascular Research, Institute of Internal Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden. johan.herlitz@hb.se.|The Prehospital Research Centre Western Sweden, University of Borås, Borås, Sweden. johan.herlitz@hb.se.
authors.forename: Johan
authors.initials: J
authors.lastname: Herlitz
authors.affiliation: The Prehospital Research Centre Western Sweden, University of Borås, Borås, Sweden. christer.axelsson@hb.se.
authors.forename: Christer
authors.initials: C
authors.lastname: Axelsson
authors.affiliation: Department of Medicine, Center for Resuscitation Science, Karolinska Institute, Stockholm, Sweden. andreas.claesson@telia.com.
authors.forename: Andreas
authors.initials: A
authors.lastname: Claesson
authors.affiliation: The Prehospital Research Centre Western Sweden, University of Borås, Borås, Sweden. anders.bremer@hb.se.
authors.forename: Anders
authors.initials: A
authors.lastname: Bremer
authors.affiliation: Centre for Applied Biostatistics, Occupational and Environmental Medicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden. thomas.karlsson@gu.se.
authors.forename: Thomas
authors.initials: T
authors.lastname: Karlsson
authors.affiliation: Department of Nursing, Universitat Rovira i Virgili, Tarragona, Spain. Mjimenezherrera@gmail.com.
authors.forename: Maria
authors.initials: M
authors.lastname: Jimenez-Herrera
authors.affiliation: Department of Cardiology, Sahlgrenska University Hospital, Gothenburg, Sweden. annica.ravn-fischer@vgregion.se.
authors.forename: Annica
authors.initials: A
authors.lastname: Ravn-Fischer
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000368:Aged; D000701:Analgesics, Opioid / Q000627:therapeutic use; D000925:Anticoagulants / Q000627:therapeutic use*; D001241:Aspirin / Q000627:therapeutic use*; D000077144:Clopidogrel; D004562:Electrocardiography; D004632:Emergency Medical Services; D005260:Female; D006801:Humans; D008297:Male; D009020:Morphine / Q000627:therapeutic use; D009203:Myocardial Infarction / Q000188:drug therapy*; D005996:Nitroglycerin / Q000627:therapeutic use; D010100:Oxygen / Q000008:administration & dosage; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use; D013548:Sweden; D013988:Ticlopidine / Q000031:analogs & derivatives / Q000627:therapeutic use; D016896:Treatment Outcome; D014665:Vasodilator Agents / Q000627:therapeutic use
chemical_list: D000319:Adrenergic beta-Antagonists; D000701:Analgesics, Opioid; D000925:Anticoagulants; D010975:Platelet Aggregation Inhibitors; D014665:Vasodilator Agents; D009020:Morphine; D000077144:Clopidogrel; D005996:Nitroglycerin; D013988:Ticlopidine; D001241:Aspirin; D010100:Oxygen