Outpatient treatment of pulmonary embolism is feasible and safe in a substantial proportion of patients

Dear Sir, Asymptomatic pulmonary embolism (PE) is frequent in proximal deep vein thrombosis (DVT) and DVT patients are now largely treated as outpatients [1-4]. It was therefore tempting to treat at least some patients with symptomatic PE in an outpatient setting. The aim of the present study was to evaluate the proportion of symptomatic PE patients with a low predicted risk (according to Wicki et al. [3] who could effectively be treated in an outpatient setting). Patients (n = 255; median age 69 years, range 18–96) were diagnosed during the period from May 1999 to December 2001 with symptomatic, objectively confirmed PE in the two participating centers. 150 patients had predefined exclusion criteria, including contraindication for anticoagulants, history or presence of drug addiction, high probability of noncompliance, body weight >110 kg, psychiatric conditions, clinically relevant impairment of renal function (creatinine clearance <30 mL min−1), thrombocytopenia (<120 G L−1), any contraindications for low molecular weight heparins (LMWHs) or standard heparin, concomitant fibrinolytic therapy, treatment with oral anticoagulants during the 24 h prior to entering the study. Recruitment was not possible on weekends, which excluded 57 additional patients. Thus, 105 patients could be included in the study, and 43 (41%) could in fact be treated entirely as outpatients (Fig. 1). Treatment consisted of a single daily subcutaneous (s.c.) injection of a weight-adjusted dose of nadroparin calcium [Fraxiforte®, 171 UI anti-factor Xa (FXa) kg−1, Sanofi-Synthelabo, France], and phenprocoumon until the international normalized ration was in the therapeutic range of 2–3 for two consecutive days (LMWH for a minimum of 5 up to 10 days). Oral anticoagulation was continued for 6–12 months. Among the 62 patients treated in hospital, only 11 had a high risk score [3], while the main reasons for the inpatient treatment was either the patient's choice or the presence of comorbidity (Fig. 1). All patients were followed up for 3 months for clinical manifestation of thromboembolism or bleedings. During the 3-month follow-up, clinically suspected recurrent DVT or PE was objectively confirmed in three patients (two in the inpatient and one in the outpatient group). No patients died, and there were no major bleeding incidents, although two minor bleedings occurred in the inpatient group. In conclusion, a substantial proportion of patients with symptomatic PE at low predicted risk of adverse outcome could be treated in an outpatient setting by means of a once daily s.c. injection of LMWH nadroparin. These data, along with an earlier report from Canada [5], call for a large-scale randomized study, with particular emphasis on safety and cost-effectiveness in PE patients with a predicted low risk of adverse outcome. Study flow chart. The project was supported by an unrestricted grant from Sanofi Synthelabo, Geneva, and in part by the Swiss National Foundation of Science (grant no. 32–059 449) and the Swiss Heart Foundation.