Common DVT Prevention Devices Could Be Ineffective
(VultusNews) – Devices that are commonly used in hospital and other inpatient settings to prevent blood clots in legs, and their complications, have not been conclusively proven to be effective.
Sequential Compression Devices (SCDs) are commonly used in hospital settings to prevent Deep Vein Thrombosis (DVTs), which are blood clots that form in deep veins that can travel to the lungs and be fatal, in patients that cannot move around easily and often; especially for patients that cannot take anti-coagulants (drugs that reduce clotting).
SCDs are sleeve like devices that fit on the legs that inflate and deflate with air in a cycle to replicate walking to improve blood flow; supposedly lowering the chance of developing a DVT.
SCDs are widely promoted to be effective in preventing DVTs, but scientific studies that directly study SCD effectiveness on preventing DVTs have mixed results and have flaws in methodology. Many studies on SCDs did not study the outcome directly, but how effective they were at moving blood in the deep veins of the legs.
Of the studies that did directly looked at the rate of DVTs in hospitalized patients (the list of the reviewed studies is at the end of this article):
Many only compared SCDs to other anti-coagulant measures, like Heparin
Most had small samples sizes
Few included DVTs that developed after the patient was discharged
Some only studied specific patient populations, like patients in Inventive Care Units, patient undergoing orthopedic operation, or those at high risk for DVTs
Those that did study patients that used SCDs vs those that did not use any anti-coagulant measures had mixed results
Many did not take into account of all known risk factors for DVTs
Many studies did not screen for asymptomatic DVTs
How are SCDs in use if they were never proven to be effective? Because SCDs were introduced before May 28, 1976, which means that they were never subject to FDA review. Any device that was commercially available before that date was grandfathered in, and did not need to go through a review process to prove safety and efficacy.
If a device is “substantially equivalent” (the device has not changed in ways that could change its safety or efficacy) to a device that was grandfathered, that device does not have to go through a full FDA review that new devices do. 337 devices under the SCD category have applied for, and gotten approved as substantially equivalent since May 28, 1976.
This does not mean that SCDs are ineffective all together, they may be generally effective or effective just for certain groups, like those at high risk for DVTs due to genetics, or underlying condition. SCDs may decrease risk when used with anti-coagulants.
The effectiveness of SCDs have not been proven or disproven.
Attached is the list of studies review by VultusNews with pertinent information. The studies that were included had to compare SCDs to no SCDs or other preventable measures.
