Patients with a first symptomatic unprovoked deep vein thrombosis are at higher risk of recurrent venous thromboembolism than patients with a first unprovoked pulmonary embolism.
BACKGROUND
Previous studies are mixed as to whether patients with unprovoked pulmonary embolism (PE) have a higher rate of venous thromboembolism (VTE) recurrence after anticoagulation is discontinued than patients with unprovoked deep vein thrombosis (DVT).


OBJECTIVE
To determine whether patients with unprovoked PE have a higher rate of VTE recurrence than patients with unprovoked DVT in a prospective multicenter cohort study.


METHODS
Six hundred and forty-six patients with a first episode of symptomatic unprovoked VTE were treated with heparin and subsequent oral anticoagulation for 5-7 months, and were followed every 6 months for recurrent VTE after their anticoagulant therapy was discontinued.


RESULTS
Of 646 patients, 194 had isolated PE, 339 had isolated DVT, and 113 had both DVT and PE. After a mean of 18 months of follow-up, there were 91 recurrent VTE events (9.5% annualized risk of recurrent VTE in the total population). The crude recurrent VTE rate for the isolated PE, isolated DVT and DVT and PE groups were 7.7%, 16.5% and 17.7%, respectively. The relative risk of recurrent VTE for isolated DVT vs. isolated PE was 2.1 (95% confidence interval 1.2-3.7).


CONCLUSIONS
This study has demonstrated that patients with a first episode of unprovoked isolated DVT are 2.1 times more likely to have a recurrent VTE episode than patients with a first episode of unprovoked isolated PE. These findings need to be considered when determining the optimal duration of anticoagulant therapy for patients with unprovoked VTE.
Kovacs
M J
MJ
Department of Hematology, London Health Sciences Centre, Victoria Hospital, London, Ontario, Canada. Michael.Kovacs@lhsc.on.ca
Kahn
S R
SR
Wells
P S
PS
Anderson
D A
DA
Chagnon
I
I
LE Gal
G
G
Solymoss
S
S
Crowther
M
M
Perrier
A
A
Ramsay
T
T
Betancourt
M T
MT
White
R H
RH
Vickars
L
L
Rodger
M A
MA
D000284:Administration, Oral; D000368:Aged; D000925:Anticoagulants / Q000627:therapeutic use; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000150:complications / Q000175:diagnosis*; D012008:Recurrence; D012306:Risk; D016896:Treatment Outcome; D054556:Venous Thromboembolism / Q000150:complications / Q000175:diagnosis*; D020246:Venous Thrombosis / Q000150:complications* / Q000628:therapy*
D000925:Anticoagulants