Natural History of Isolated Deep Vein Thrombosis of the Calf (CALTHRO)
Whether isolated distal DVT (IDDVT), DVT confined to the calf, should be looked for and diagnosed to allow them to be treated with anticoagulants remains one of the still unsolved issues in vascular medicine, especially because of the insufficient data on clinical risks of untreated distal DVT. Management studies have shown that it is safe to withhold anticoagulation in outpatients with suspected DVT if compression ultrasonography (CUS) limited to the proximal deep veins yields normal results on presentation and on repeated examination after 5 to 7 days. This strategy is based on the premise that IDDVT do not need to be diagnosed and treated, what is necessary when they extend involving the proximal veins. There is no general agreement, however, on the assumption that the non-extending IDDVT do not need to be diagnosed and treated, and many authors recommend to perform a single CUS examination extended to the distal deep veins. All the available studies have treated with anticoagulants the diagnosed IDDVT and no adequate information is available on the risk of IDDVT left untreated.
The present study, performed in outpatients with suspected leg DVT, aims at assessing the clinical consequences of IDDVT diagnosed (by a complete US investigation) but not treated because the results of this investigation remain blind to both the patient and the treating doctor, whereas the diagnostic-therapeutic procedure remains the usual one, based on CUS investigation limited to diagnose proximal DVT, to be repeated after 5-7 days (or earlier) to exclude an extension to proximal veins of an IDDVT potentially present.
Isolated Distal DVT
Other: Ultrasound examination of leg veins
|Study Design:||Observational Model: Cohort
Time Perspective: Prospective
|Official Title:||Diagnosis and Evolution of Isolated Deep Vein Thrombosis of the Calf in Symptomatic Outpatients. The Blind, Prospective "CALTHRO" Study.|
- Thrombotic complications (deep vein thrombosis and/or pulmonary embolism within three months from first examination [ Time Frame: three months from first examination ] [ Designated as safety issue: No ]
- other vascular complications; how many isolated distal DVT will be diagnosed [ Time Frame: three months from first examination ] [ Designated as safety issue: No ]
|Study Start Date:||September 2005|
|Study Completion Date:||September 2009|
|Primary Completion Date:||September 2009 (Final data collection date for primary outcome measure)|
Outpatients with suspected leg DVT after exclusion of proximal DVT
Other: Ultrasound examination of leg veins
Outpatients symptomatic for leg DVT follow the standard diagnostic procedure (ultrasound examination of proximal deep veins, pre-test clinical probability and D-dimer, and a second US after 5-7 days) to exclude proximal DVT; they also receive by another doctor a complete US examination of the deep leg veins to assess the presence of isolated calf DVT, the results of the latter examination are kept blind to the patient and to the treating doctor, and disclosed after three months
Outpatients symptomatic for suspected DVT of a leg are examined by a vascular doctor according to standard procedure based on pre-test clinical probability (PTCP) assessment, D-dimer assay and a CUS limited to the proximal deep veins. Those in whom a proximal DVT is excluded and have intermediate/high PTCP or altered D-dimer level are eligible for the study. The included patients are immediately submitted to an extensive echo-color-Doppler examination of calf deep veins by a different vascular doctor and results are closed in an envelope that will be open after three months (or before if necessary). In the meantime, patients will follow the standard diagnostic procedure: they receive an appointment to come back in 5-7 days for a further CUS examination, or even before in case of worsening of symptoms/signs. All the included patients receive a telephone call after three months to exclude possible complications.
|Angiology & Blood Coagulation, Policlinico S. Orsola-Malpighi|
|Bologna, Italy, 40138|
|Servizio di Fisiopatologia Vascoalre, Casa di Cura Villa Serena|
|Pescara, Italy, 65100|
|Principal Investigator:||Gualtiero Palareti, MD||Azienda Ospedaliero-Universitaria di Bologna, Policlinico S. Orsola-Malpighi|