This study will utilize a retrospective cohort design. Using the Clinical Practice Research Datalink (CPRD) linked with Hospital Episode Statistics (HES) datasets, all patients with a record of VTE diagnosis between 1 April, 2008 and 31 March, 2013 will be identified and followed from the occurrence of VTE (index date) to the first of 24 months after the index date, end of the study period, leaving the database, or death.

Inclusion Criteria:

VTE events will be included if:

• they are identified by at least one Read code diagnosis of acute VTE in the CPRD, or one ICD-10 code of VTE in the HES database, during the study period; and
• they occurred in patients ≥ 18 years old at time of VTE occurrence; and
• CPRD acceptability quality criteria are present

Exclusion Criteria:

VTE events will be excluded if:

• Patients have fewer than 12 months of computerized data available prior to VTE occurrence. The date of start of computerized records will be the latter of the patient's date of current registration with the practice or the practice's Up-to-Standard (UTS) date (date from which practice data is of research quality)

Primary care clinic, community sample and residents of a community