P1255Comparative safety and effectiveness of standard doses of apixaban versus dabigatran, rivaroxaban, and VKAs in non-valvular atrial fibrillation patients in France: the NAXOS study

Background

Real-world data comparing all available oral anticoagulants (OAC) on a nationwide scale (i.e. in France: apixaban, rivaroxaban, dabigatran and vitamin K antagonists – VKAs) are lacking. In everyday practice, oral anticoagulants are often underdosed, which may render comparisons between agents difficult.

Purpose and methods

NAXOS is a French real-world study comparing the safety (major bleeding), effectiveness (stroke, systemic thromboembolic events (STE)) and all-cause mortality for apixaban, dabigatran, rivaroxaban, and VKAs, in adult patients with non-valvular atrial fibrillation (NVAF) initiating a given OAC between 2014 and 2016. The French national health insurance data (SNIIRAM) were used. Analyses were performed with adjustment on propensity scores. To avoid bias potentially related to underdosing, the present analysis included only patients receiving standard doses of apixaban (5mg bid), rivaroxaban (20mg od), and dabigatran (150 mg bid), or VKAs. Only OAC naïve patients were included.

Results

In the OAC-naive cohorts treated with apixaban, rivaroxaban, and dabigatran, 54,575 (62.3%), 65,208 (65.2%), and 9,000 (42.4%), respectively, had the standard dose at the index dispensation, and 112,628 patients received VKAs. After adjustment on propensity scores, apixaban 5 mg was associated with a lower risk of major bleeding, compared to VKAs (Hazard Ratio: 0.47; 95% CI: 0.43–0.51) and rivaroxaban 20mg (HR: 0.64; 0.59–0.71), but not to dabigatran 150 mg (HR: 0.97; 0.79–1.18). Apixaban was associated with a lower risk of stroke and STE, compared to VKAs (HR: 0.62; 0.56–0.69) but not to rivaroxaban (HR: 1.03; 0.92–1.16), and dabigatran (HR: 0.96; 0.76–1.21). Apixaban showed a lower risk of all-cause mortality compared to VKAs (HR: 0.44; 0.41–0.47) and rivaroxaban (HR: 0.87; 0.81–0.94) but not to dabigatran (HR: 1.10; 0.92–1.32).

Figure 1. Forest plot presenting the results of the standard dose analysis (PS adjusted).

Conclusions

The NAXOS population-based country-wide observational study shows that 42% to 65% of patients were treated with standard doses of OACs. Analyses of standard doses confirmed the superiority of apixaban compared with VKAs for the three studied outcomes and suggests better safety profile of apixaban compared to rivaroxaban but similar to dabigatran.

Acknowledgement/Funding

The Alliance Bristol-Myers Squibb/Pfizer

P1-10-02: Burden of Brain Metastases in HER2−Positive Breast Cancer: Healthcare Use and Costs from a French Observational Retrospective Multicenter Study

Background HER2+ status is associated with poor prognosis and a high incidence of brain metastases (BM) in breast cancer (BC). Addition of HER2−targeted therapies to conventional chemotherapy has significantly improved survival in HER2+ patients (pts). Management of BM implies a multidisciplinary therapeutic approach involving medical oncology, radiation oncology and neurosurgery teams. Nevertheless available data evaluating health resources use and associated costs are limited. Our objective was to describe treatment patterns and healthcare costs associated with HER2+ BMBC patients.

Patients and methods An observational retrospective study was conducted on 207 HER2+ BC pts, newly diagnosed with BM as first site of relapse or as secondary metastases between January 2006 and December 2008. Pts were recruited in 10 hospitals, all funded by a prospective payment system based on Diagnosis Related Groups (DRG). Individual data concerning initial diagnosis, distant and BM relapses, treatments, complications and hospitalization stays were collected during a 2 year — follow-up. DRGs 2007 official tariffs (per-case payment basis) and 2007 expensive innovative drugs tariffs (drugs paid to hospitals by Health Insurance in addition to per-case payments) were used to estimate direct medical costs from the Health Insurance perspective. Survival was estimated using Kaplan Meier method. In the presence of cost-censored data, a partitioned estimator was used to adjust censoring costs (Bang and Tsiatis, Biometrics, 2002).

Results 91.8% (190/207) of BMBC pts received radiation therapy, 84.5% (175/207) received chemotherapy including HER2 targeted treatments and 12.6% (26/207) were treated by neurosurgery. 72.5% (150/207) of pts were hospitalized at least once during the follow-up period. Pts had on average 2.90 hospital stays (range 1–8). The median duration of stay was 9 days (1-221). Complications leading to re-hospitalization were recorded in 45.9% (95/207) of pts. The median overall survival from the diagnosis of BM was 13 m. Hospital healthcare costs were concentrated on the 6 first months following BM diagnosis. Mean cost of BMBC management was 18,480€/patient within the 6 first months and decreased to 16,306€ from 7–12 months, 15,844€ from 13–18 months, and 15,225€ from 19–24 months. The proportion of costs attributed to inpatient hospitalizations stay (treatments and complications) was similar to the one attributed to drugs whatever the period of follow-up. Pts with BM as first site of relapse consumed more healthcare resources compared to pts with secondary BM (38,813€/pt vs 32,253€/pt after one year of follow-up, respectively).

Conclusions Healthcare resources spending is mainly concentrated at the beginning of metastatic disease management, especially for patients with BM as first site of relapse. These results illustrate the use of expensive treatments in the first months following BM diagnosis. Individual data derived from this observational study allowed us to gather more specifically treatment patterns for HER2+ BMBC in order to estimate the costs more accurately.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-10-02.