Epidemiology and Treatment Patterns of Venous Thromboembolism: an Observational Study of Nationwide Time-Series Trends in Japan

INTRODUCTION: Previous studies on anticoagulation treatment trends have mostly focused on hospitalized patients. This study aimed to clarify the treatment status of patients with venous thromboembolism (VTE) in Japan from 2011 to 2018, including outpatients, and to assess adherence with current guidelines. METHODS: Data of inpatients and outpatients who were treated for VTE were extracted from a nationwide claims database (Medical Data Vision Co., Ltd., Tokyo, Japan) and analyzed. RESULTS: The study included 79,330 patients with VTE; half were diagnosed during hospitalization for diseases other than VTE. The proportion of outpatient treatment increased significantly from 2015 to 2018 (Cochran–Armitage trend test, P < 0.0001), while 80% were anticoagulated in hospital after pulmonary embolism (PE) diagnosis. The proportion of patients with VTE treated as outpatients was no lower than the proportion of inpatients, even in the presence of active cancer, and there were no clear differences in anticoagulant choices. Treatment with direct oral anticoagulants (DOACs) did not always include the recommended initial intensification therapy. There was wide variation in the duration of DOAC treatment and the median duration of use was shorter than that recommended in VTE treatment guidelines. CONCLUSION: While the gradual increase in VTE outpatient treatment appears to be in line with guideline recommendations, PE outpatient treatment could be further facilitated. The large proportion of patients diagnosed with VTE during hospitalization for other conditions suggests the importance of further utilizing in-hospital manuals for thrombosis prevention. The presence or absence of cancer did not appear to affect the basic treatment strategy of anticoagulation for VTE. Future studies are expected to better define the characteristics of patients who can be safely and effectively treated in an outpatient setting, and to examine whether anticoagulation for a shorter treatment period than recommended by the guidelines or DOAC therapy without initial intensification would improve patient outcomes. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40119-022-00284-4.