At each participating site, patients are screened by the site investigators and checked for eligibility (Table 1). All patients with objectively confirmed acute symptomatic or asymptomatic VTE (i.e. DVT, PE, or both). More recently, in an attempt to similarly understand the presentation, treatment pattern, and outcomes of other thrombotic conditions, RIETE has also started to enroll patients with superficial vein thrombosis, splanchnic vein thrombosis (i.e. thrombosis involves the mesenteric, splenic, or portal veins), retinal vein thrombosis, and cerebral vein thrombosis. At each participating center, every attempt is made to enroll consecutive patients and RIETE investigators are committed, by contract agreement, to enroll consecutive patients. Periodic audits of the sites have confirmed consecutiveness. Further, comparison against the Spanish Ministry of Health database has shown that patients in RIETE have similar characteristics to the data from all-comers with VTE in that database.(28 (link)) No duplicate entries are permitted and patients who are enrolled in blinded treatment trials are ineligible.
Methods of DVT diagnosis include contrast venography, ultrasonography, magnetic resonance, or rarely in the past, plethysmography (only 172 patients in the entire cohort). PE is diagnosed on the basis of pulmonary angiography, contrast-enhanced computed tomography (CT) of the chest (specifically CT pulmonary angiography), lung scintigraphy, or rarely on the basis of confirmed DVT in patients with signs and symptoms of PE.
RIETE, by design, does not currently enroll patients with intracardiac thrombi in the absence of VTE. As of June 30, 2017, a total of 72,107 valid patients with acute VTE have been enrolled in RIETE. Currently, RIETE has 179 participating sites from 24 countries and across 3 continents. There has been a growth, over time, in the number of involved sites and countries (Figure 2, Panels A and B).