The objective of this proposal is to develop and validate diagnostic and prognostic (including short-term and long-term prognoses) prediction models for patients with venous thromboembolism (VTE) in China.

Venous thromboembolism (VTE), which clinically manifests as deep vein thrombosis (DVT) and pulmonary embolism (PE), is one of the leading causes of mortality that need to be accurately diagnosed and effectively managed. Although a number of clinical decision rules in the domain of VTE have been presented in the literature, such as the well-known prediction models developed by Wells and colleagues, the prognostic models to assess VTE recurrence risk in patients who suffered from a VTE or the Pulmonary Embolism Severity Index (PESI) for short-term mortality risk in PE patients, and various other diagnostic models for both DVT and PE. They are few designed for Chinese patients. The primary objective of this proposal is to develop and validate diagnostic and prognostic (including short-term and long-term prognoses) prediction models for patients with VTE in China.

Inclusion Criteria:

1. > 18 years old
2. First episode of PE and/or DVT (diagnosed by pulmonary angiogram, chest computed tomography pulmonary angiography(CTPA), Ventilation/Perfusion (V/Q) lung scan read as high probability by the radiologist, and/or (+) bilateral lower limb venous compression ultrasonography (CCUS))

Exclusion Criteria:

1. Patients with prior VTE
2. Cannot provide written informed consent
3. Unable to read questionnaire in Chinese or English
4. a record of pregnancy in the preceding 12 months

Development and validation of diagnostic prediction model:

Participants will undergo recruitment from the emergency department of five general urban hospitals in China, including Shanghai Tenth People's Hospital; Nanfang Hospital of Southern Medical University; First Affiliated Hospital, Sun Yat-Sen University; Zhongshan Hospital Xuhui Branch, Fudan University; Shanghai Baoshan Luo Dian Hospital; from March 1, 2019.

Development and validation of prognostic prediction model:

The investigators will identify patients with VTE from 5 thrombosis centers in China, including Shanghai Tenth People's Hospital; Nanfang Hospital of Southern Medical University; First Affiliated Hospital, Sun Yat-Sen University; Zhongshan Hospital Xuhui Branch, Fudan University; Shanghai Baoshan Luo Dian Hospital; between January 2014 and December 2018 using the Hospital Information Manage System(HIMS) database.