Treatment of distal deep vein thrombosis

Background The treatment of distal (below the knee) deep vein thrombosis (DVT) is not clearly established. Distal DVT can either be treated with anticoagulation, or monitored with close follow‐up to detect progression to the proximal veins (above the knee), which requires anticoagulation. Proponents of this monitoring strategy base their decision to withhold anticoagulation on the fact that progression is rare and most people can be spared from potential bleeding and other adverse effects of anticoagulation. Objectives To assess the effects of different treatment interventions for people with distal (below the knee) deep vein thrombosis (DVT). Search methods The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase and CINAHL databases and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 12 February 2019. We also undertook reference checking to identify additional studies. Selection criteria Randomised controlled trials (RCTs) for the treatment of distal DVT. Data collection and analysis Two review authors independently selected trials and extracted data. We resolved disagreements by discussion. Primary outcomes of interest were recurrence of venous thromboembolism (VTE), DVT and major bleeding and follow up ranged from three months to two years. We performed fixed‐effect model meta‐analyses with risk ratio (RRs) and 95% confidence intervals (CIs). We assessed the certainty of the evidence using GRADE. Main results We identified eight RCTs reporting on 1239 participants. Five trials randomised participants to anticoagulation for up to three months versus no anticoagulation. Three trials compared anticoagulation treatment for different time periods. Anticoagulant compared to no intervention or placebo for distal DVT treatment Anticoagulation with a vitamin K antagonist (VKA) reduced the risk of recurrent VTE during follow‐up compared with participants receiving no anticoagulation (RR 0.34, 95% CI 0.15 to 0.77; 5 studies, 496 participants; I2 = 3%; high‐certainty evidence), and reduced the risk of recurrence of DVT (RR 0.25, 95% CI 0.10 to 0.67; 5 studies, 496 participants; I2 = 0%; high‐certainty evidence). There was no clear effect on risk of pulmonary embolism (PE) (RR 0.81, 95% CI 0.18 to 3.59; 4 studies, 480 participants; I2 = 0%; low‐certainty evidence). There was little to no difference in major bleeding with anticoagula