title: The clinical course of pulmonary embolism patients anticoagulated for 1 year: results of a prospective, observational, cohort study.
abstract: BACKGROUND
  Few studies have examined the clinical course of pulmonary embolism (PE) in patients anticoagulated continuously for 1 year.
  
  
  OBJECTIVE
  We sought to determine the incidence of death, recurrent PE and bleeding during anticoagulation in the first year after acute PE, and to assess associated risk factors.
  
  
  METHODS
  All consecutive PE patients who were referred to our center in Pisa, Italy between 2001 and 2005 received a conventional initial treatment, followed by vitamin K antagonists [international normalized ratio (INR), 2.0-3.0] for 1 year. They were followed-up at scheduled times at the study center. The development of recurrent PE was objectively documented and recorded.
  
  
  RESULTS
  Out of 497 patients, 48 (9.6%) developed recurrent PE, which was fatal in 36. Of these 48 events, 39 occurred within 10 days of diagnosis and only two patients had a non-fatal recurrent PE between 6 and 12 months. Risk factors associated with the risk for overall recurrent PE were persistent severe dyspnoea (P = 0.007), a high perfusion defect score index (PDI) (P = 0.003) and cardiopulmonary co-morbidities (P = 0.005). Unprovoked presentation (P = 0.030), persistent severe dyspnoea (P = 0.011) and a high PDI (P = 0.001) predicted the risk for fatal PE. Overall bleeding incidence was 3.4%, no cases of bleeding occurred between 180 and 360 days post-diagnosis.
  
  
  CONCLUSIONS
  In spite of conventional anticoagulation, a proportion of patients with PE experience both a fatal and non-fatal recurrent embolism within the first year. The large majority of these occur within the days proceeding diagnosis, with only a small minority occurring in the last 6 months. No bleeding was observed after 6 months. Therefore, prolonging anticoagulation for 1 year represents both a safe and effective treatment.
authors.affiliation: Section of Respiratory Disease, Cardio Thoracic and Vascular Department, University of Pisa, Pisa, Italy. a.palla@med.unipi.it
authors.forename: A
authors.initials: A
authors.lastname: Palla
authors.forename: C
authors.initials: C
authors.lastname: Ribas
authors.forename: G
authors.initials: G
authors.lastname: Rossi
authors.forename: P
authors.initials: P
authors.lastname: Pepe
authors.forename: L
authors.initials: L
authors.lastname: Marconi
authors.forename: P
authors.initials: P
authors.lastname: Prandoni
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage* / Q000009:adverse effects; D004334:Drug Administration Schedule; D005260:Female; D005500:Follow-Up Studies; D006470:Hemorrhage / Q000139:chemically induced; D006801:Humans; D019934:International Normalized Ratio; D007558:Italy / Q000453:epidemiology; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000097:blood / Q000188:drug therapy* / Q000401:mortality; D012008:Recurrence; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014812:Vitamin K / Q000037:antagonists & inhibitors
chemical_list: D000925:Anticoagulants; D014812:Vitamin K