title: The anticoagulation of calf thrombosis (ACT) project: results from the randomized controlled external pilot trial.
abstract: BACKGROUND
  There is currently little evidence defining the clinical importance of detecting and treating isolated distal DVT (IDDVT). International guidelines vary regarding diagnostic and therapeutic advice. The potential benefits of anticoagulation are unquantified. We sought to evaluate the feasibility of a randomized controlled study within a modern framework and provide a primary outcome point estimate.
  
  
  METHODS
  In this open-label, external pilot randomized controlled trial, consecutive, symptomatic, ambulatory patients with IDDVT were approached for inclusion. Participants were allocated to receive either therapeutic anticoagulation or conservative management. Patients underwent blinded color-duplex imaging at 7 and 21 days and follow-up at 3 months. Principal feasibility outcomes included recruitment rate and attrition. The principal clinical outcome was a composite including proximal propagation, pulmonary embolism, death attributable to VTE disease, or major bleeding. Analysis was by intention to treat.
  
  
  RESULTS
  In total, 93 patients with IDDVT were screened, and 70 of those eligible (88.6%) were recruited. All patients but one were followed-up by direct contact after 90 days. Allocation crossover occurred in 15 patients (21.4%). The principal clinical outcome occurred in four of 35 of those conservatively treated (11.4%) and zero of 35 in the anticoagulated group (absolute risk reduction, 11.4%; 95% CI, -1.5 to 26.7, P = .11, number needed to treat of nine). There were no major bleeding episodes.
  
  
  CONCLUSIONS
  We have established the feasibility of definitive study regarding the value of therapeutic anticoagulation in IDDVT and provide an approximate point estimate for serious complications with a contemporary conservative strategy.
  
  
  BACKGROUND
  Current Controlled Trials; No.: ISRCTN75175695; URL: www.controlled-trials.com.
authors.affiliation: Emergency Department, The University of Manchester, Manchester, England. Electronic address: danielhorner@nhs.net.
authors.forename: Daniel
authors.initials: D
authors.lastname: Horner
authors.affiliation: Thrombosis Group, The Ottawa Hospital, Ottawa, ON, Canada.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Hogg
authors.affiliation: Emergency Department, The University of Manchester, Manchester, England.
authors.forename: Richard
authors.initials: R
authors.lastname: Body
authors.affiliation: Manchester Royal Infirmary, and Department of Haematology, Central Manchester University Hospitals, NHS Foundation Trust, Manchester, England.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Nash
authors.affiliation: Department of Haematology, Cambridge University Hospitals, NHS Foundation Trust, Cambridge, England.
authors.forename: Trevor
authors.initials: T
authors.lastname: Baglin
authors.affiliation: Emergency Department, The University of Manchester, Manchester, England.
authors.forename: Kevin
authors.initials: K
authors.lastname: Mackway-Jones
mesh_terms: D000328:Adult; D000368:Aged; D000925:Anticoagulants / Q000627:therapeutic use*; D016001:Confidence Intervals; D005260:Female; D005500:Follow-Up Studies; D006784:Hospitals, Teaching; D006801:Humans; D007866:Leg / Q000098:blood supply; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D010865:Pilot Projects; D012008:Recurrence; D012016:Reference Values; D018570:Risk Assessment; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D013997:Time Factors; D016896:Treatment Outcome; D018617:Ultrasonography, Doppler, Pulsed / Q000379:methods*; D020246:Venous Thrombosis / Q000000981:diagnostic imaging* / Q000188:drug therapy*
chemical_list: D000925:Anticoagulants