Xalia, a Non-Interventional Study Comparing Rivaroxaban with Standard Anticoagulation for Initial and Long-Term Therapy in Deep Vein Thrombosis

Background

Rivaroxaban is approved for the treatment and secondary prevention of acute deep vein thrombosis (DVT) and pulmonary embolism (PE). The aim of the XALIA study was to provide information on the safety and effectiveness of rivaroxaban in routine patient care in a heterogeneous non-selected venous thromboembolism (VTE) population.

Methods

XALIA is a multicenter, prospective, non-interventional study and included patients aged ≥18 years with objectively confirmed, acute DVT treated with oral rivaroxaban (the initial approved VTE treatment indication) or standard anticoagulation therapy for ≥3 months. After approval of rivaroxaban for the PE indication, patients with DVT and concomitant PE were also included. Type, dose, and duration of drug therapy were at the physician's discretion. Patients were followed up until 30 days after the end of treatment or study conclusion. The primary statistical analysis includes a descriptive analysis of the primary outcomes of major bleeding and recurrent VTE, which were centrally adjudicated under assessor-blinded conditions; hazard ratios (HRs) with 95% confidence intervals (CIs) from a Cox regression model adjusted for active cancer only are shown.

Results

This study enrolled 5142 patients across 21 countries, in Europe, Israel, and Canada, between June 2012 and March 2015. Six patients did not receive anticoagulant therapy and 368 patients were treated for >2–14 days with heparin/fondaparinux or 1–14 days with a vitamin K antagonist (VKA) before starting rivaroxaban (as described in the XALIA protocol paper, the latter were defined as ‘early switchers' and included in a separate sensitivity analysis [Ageno et al. Thromb J 2014;12:16]).

Thus, the primary analysis comprised 2619 patients in the rivaroxaban group (rivaroxaban only or </= 2 days of parenteral treatment) and 2149 in the standard-therapy group (of whom most received low molecular weight heparin plus a VKA). The mean patient ages were 57.3 and 63.0 years, 55% and 52% were male, 5.6% and 19.1% had active cancer at baseline, 3.9% and 10.1% had creatinine clearance (CrCl) <50 mL/min, and 8.4% and 11.9% also had PE in the rivaroxaban and standard-therapy groups, respectively. Patient demographics and baseline clinical characteristics are shown (Table 1).

The major bleeding rate was 1.23%/year (n=19) for patients in the rivaroxaban group and 3.32%/year (n=47) for patients in the standard-therapy group. After adjustment for active cancer at baseline, the HR was 0.41 (95% CI 0.24–0.71). The recurrent VTE rate was 2.21%/year (n=34) for patients in the rivaroxaban group and 3.64%/year (n=51) for patients in the standard-therapy group. The HR adjusted for active cancer at baseline was 0.64 (95% CI 0.41–1.00).

In the early switcher group, the mean patient age was 59.3 years, 57% were male, 8.2% had active cancer at baseline, 6.5% had CrCl <50 mL/min, and 20.9% had DVT plus PE (Table 1). The event rate in the early switcher group for major bleeding was 1.97%/year and the event rate for recurrent VTE was 2.76%/year.

Conclusions

XALIA is the first large non-interventional study comparing the safety and effectiveness of a direct oral anticoagulant, specifically rivaroxaban, in VTE treatment with conventional anticoagulation therapy. The outcomes are consistent with the findings of the EINSTEIN phase III studies, with low rates of major bleeding and symptomatic recurrent VTE (EINSTEIN Investigators. N Engl J Med 2010;363:2499). However, the unadjusted data show that treatment allocation may have been influenced by patient characteristics such as age and co-morbidities, which could affect outcomes. Owing to the differences in patient baseline characteristics, ongoing propensity-score analyses will be presented.

Table 1: Patient Demographics and Baseline Clinical Characteristics

Characteristic	Rivaroxaban (n=2619)	Standard therapy (n=2149)	Early switchers (n=368)
Mean age, years	57.3	63.0	59.3
Male (%)	55	52	57
Active cancer (%)	5.6	19.1	8.2
CrCl <50 mL/min (%)	3.9	10.1	6.5
Concomitant PE (%)	8.4	11.9	20.9