Thrombotic Events during Oral Anticoagulant Treatment: Results of the Inception-cohort, Prospective, Collaborative ISCOAT Study

Abstract

SummaryThe paper reports on rate and type of thrombotic events occurring during the observational, prospective, inception-cohort, multicenter ISCOAT study. 2,745 unselected, daily practice patients, consecutively referring to 34 Italian anticoagulation clinics to monitor the oral anticoagulant treatment, were included in the study from beginning of their first anticoagulant course. During a total follow-up of 2,011 patient-years of treatment 70 thrombotic events (3.5 per 100 patient years) were recorded in 67 patients: 20 fatal (1%), 39 major (1.9%) and 11 minor (0.6%). 34/70 events occurred within the first 90 days of treatment (relative risk - at multivariate analysis - of <90 days vs. >90 = 20.6, C.I. 12.7-33.5; p <0.0001). The risk was higher in patients aged >70 y (1.62, C.I. 1.0-2.61; p <0.05), and when indication for anticoagulant treatment was peripheral/cerebral arterial disease (1.84, C.I. 1.01-3.36; p <0.05). The frequency of thrombotic events was 17.5% when international normalised ratio (INR) levels were <1.5, decreasing to 2.3% for INRs within the 2-2.99 category (relative risk of INRs <2.0 vs. >2 = 1.88, C.1.1.16-3.07; p <0.05).The recorded rate of thrombotic events was lower than that reported in the few available studies. A greater risk should be expected during the first 90 days of treatment, when anticoagulation levels are <2.0 INR, in patients > 70 years and in those with cerebrovascular/peripheral arterial disease.

Anticoagulation intensity and outcomes among patients prescribed oral anticoagulant therapy: a systematic review and meta-analysis

“…[24][25][26][27][28][29] For our base analysis, we grouped the person-years of observation and events from these studies in the ratio category of 3-5. We repeated our analysis after imputing the person-years of observation and the number of events that occurred when the ratio exceeded 5.…”

“…We included 19 studies published between 1992 and 2007 in our analysis 6,[21][22][23][24][25][26][27][28][29][32][33][34][35][36][37][38][39][40] (Table 1). Of these, 14 reported both hemorrhagic and thromboembolic events, 6,21,23,25,[27][28][29][32][33][34][35][36][37]39 3 reported only hemorrhagic events, 22,38,40 and 2 reported only thromboembolic events.…”

“…Of these, 14 reported both hemorrhagic and thromboembolic events, 6,21,23,25,[27][28][29][32][33][34][35][36][37]39 3 reported only hemorrhagic events, 22,38,40 and 2 reported only thromboembolic events. 24,26 Half were retrospective cohort studies and two-thirds (68%) were community-based studies. Warfarin was the only anticoagulant used in 9 of the studies.…”

Diagnosis and Treatment of Lower Extremity Deep Vein Thrombosis: Korean Practice Guidelines

“…In the PROLONG study, patients with an abnormal D-dimer level 1 month after discontinuation of anticoagulant for treatment of unprovoked VTE were randomized to resume warfarin or not. When the primary end-points of recurrent VTE and major bleeding were assessed, there were three events among the 103 [133,134]. Poor-quality INR control, as assessed by the percentage of time with INR <1.5, is associated with a long-term higher risk of recurrent VTE after eventual anticoagulant cessation (RR, 2.7; 95% CI, 1.39-5.25; P=0.003) [135].…”

Telemedicine For Managing Patients on Oral Anticoagulant Therapy

“…In the ISCOAT study, the most large, prospective Italian investigation study, including a cohort from 34 ACs, the incidence of major bleeding complications was 1.25 for 100 patient-years, whereas the incidence of thromboembolic events was 3.5 for 100 patient-years (Palareti el al., 1997). Literature analysis showed that patients on RMC had a 2-fold increase (2.5 vs 1.25% patient-years) and 3-fold increase (10.5 vs 3.5% patient-years) of bleeding and thromboembolic risks, respectively, compared to patients followed by AC (Palareti et al, 1996;Palareti et al, 1997) (Tab. 1).…”