We define a VTE prevention protocol to be a standardized VTE risk assessment, linked to a menu of appropriate VTE prophylaxis options for each level of risk [23–25]. Guidance for management of patients with contraindications to pharmacologic prophylaxis should also be included. The best protocols provide decision support at the point of care, and yet are user friendly and efficient to use, and preserve the ability to customize care for special patient situations or circumstances [23–26].
Who administers the protocol?
Conceivably, anyone in the medical center (e.g. a nurse or pharmacist) could administer the risk assessment model and present the results to the physician for action. However, our collective experience suggests that the VTE prevention protocol is most effective when embedded in commonly used admission, transfer, and perioperative order sets. Across VTE collaboratives, the physician consistently appears to be in the best position to understand all components of VTE risk, along with the possible contraindications to pharmacologic prophylaxis. Furthermore, an immediate connection in time and space of the VTE risk assessment to the ordering process makes for a more reliable and direct route for ordering adequate prophylaxis.
How should I design the risk assessment into the order set?
We recommend integrating a simple text based model with no more than three levels of VTE risk. An illustrative paper order set is depicted in the Appendix. While this example depicts enoxaparin as the low molecular weight heparin of choice, local formulary issues and medical staff opinion will dictate these choices, and with this illustration we are not implying one is superior to the other.
At one extreme of VTE risk are patients that would benefit from both a low molecular weight heparin or fondaparinux and mechanical prophylaxis (while not depicted in this example, some institutions also offer warfarin as an option for these high risk patients). Major orthopedic surgery, multiple major trauma, spinal cord injury with paresis, and abdominal/pelvic cancer patients undergoing surgery are common choices for patients in this very high risk category. Choices for renal insufficiency and end stage renal disease are offered with simple caveats in parentheses. In our medical center, 15–20% of our inpatients fall into this highest risk category.
At the other extreme are patients at such low risk for VTE they do not require any prophylaxis other than education and ambulation. This model accepts a paradigm in which almost all inpatients are at risk for VTE and need pharmacologic prophylaxis, with the exception of the few who are expected to be in the medical center for less than 48 h, or who have a paucity of risk factors and are fully and independently ambulating. This low risk subset represents less than 5% of inpatients at our medical center.
The majority of inpatients occupy the middle category of VTE risk. While there is some evidence favoring low molecular weight heparin (LMWH) versus unfractionated heparin (UFH) in subsets of this population [27, 28], evidence is fairly weak at this risk level, and either choice is usually seen as acceptable. Note that UFH 5000 units dosed every 12 h has been relegated a secondary role, suitable only for underweight or geriatric patients. This choice is admittedly somewhat arbitrary, but the trials comparing LMWH to UFH regimens used 5000 units q 8 h dosing schedules in the comparison arm [27–30]. On the whole, there is more evidence for using UFH 5000 q 8 h schedules compared to UFH 5000 q 12 h regimens. Attempts to tease out populations in which UFH 5000 q 8 h is acceptable but UFH 5000 q 12 h regimens are not are generally not worth the effort, and lead to unnecessary clutter and complexity to order sets.
Contraindications and a full listing of VTE risk factors should not occupy precious “real estate” on the front page of an order set, but should be readily accessible by instructions embedded there. Sequential compression devices are specifically listed as the default choice for mechanical prophylaxis. Mechanical prophylaxis is relegated to an adjunctive role, or as a first line choice when pharmacologic prophylaxis is not feasible. Aspirin is not listed as an acceptable choice for DVT prophylaxis, which is consistent with prominent guidelines . Improvement teams need not feel restricted in the design details of the order set or the choices they offer for each level of risk, providing they retain the most important design concepts and avoid the most common errors outlined below.
Common errors in constructing/implementing a VTE prevention order set
Not providing enough guidance: a prompt is not a protocol
Many centers have order sets that list options for VTE prophylaxis without providing any guidance for which choice is most appropriate or desirable. Mechanical prophylaxis, varying pharmacologic agents with different doses, and no prophylaxis are inappropriately offered as equal options, even though most inpatients have significant VTE risk factors [7, 11], and in spite of strong evidence based recommendations  relegating mechanical prophylaxis to an adjunctive role for pharmacologic prophylaxis (unless there are contraindications to pharmacologic prophylaxis).
Providing too much guidance: order sets can become too complicated
It is tempting to create an order set that provides comprehensive guidance and outlines the best prophylaxis for the entire spectrum of conditions. Improvement teams must strike a fine balance between providing a good risk assessment for the great majority of the inpatient population, yet keeping things simple and efficient in everyday use. We have encountered three page stand-alone order VTE prophylaxis order sets that would provide excellent guidance if used, but they simply collect dust and are adapted by only a minority of providers. Some order sets offer 4-6 levels of VTE risk, but the evidence to distinguish the levels of risk, and the differences in attendant prophylaxis choices, is often weak. We have found that 2–3 levels of VTE risk are enough.
Many centers have tried to adapt point based models inspired by the pioneering work of Caprini and colleagues [18, 21]. In theory, this model is attractive. Risk factors depicting the clinical setting and the patient are assigned points, and the cumulative point total is entered into the order set, with guidance for prophylaxis hinging on this cumulative point total. In practice, this risk assessment method is often fraught with problems. Hurried clinicians do not reliably add up the points for each risk, and inter-observer agreement suffers as a result. The point scoring system is somewhat arbitrary, and has not yet been validated in the literature. Most importantly, the point based systems are too long and bulky to integrate into a variety of existing order sets, and as a result, reliability of use and wide adaption is problematic.
Offering non-pharmacologic prophylaxis as a first line option
Pharmacologic prophylaxis is recommended as the first line choice for inpatients at risk for VTE. Mechanical prophylaxis can (and often should) be offered as an adjunct to pharmacologic prophylaxis, but it should not be offered as a first line choice for prophylaxis in the absence of contraindications to VTE prophylaxis.
Link between risk level and prophylaxis choices are separated in time or space
Ideally, the VTE risk assessment is performed quickly, and the choices for appropriate prophylaxis are directly and inescapably linked to each level of risk. If the act of ordering VTE prophylaxis is separated in any way from the risk assessment, the reliability of ordering adequate prophylaxis deteriorates.
Failure to revise pre-existing and conflicting order sets
Most institutions have a variety of admission, transfer, and order sets in place. These order sets often already “touch” the majority of adult inpatients, and they often have a highly variable approach to VTE prophylaxis embedded within them. We strongly urge improvement teams to examine all existing admission, transfer, and perioperative order sets with reference to VTE prophylaxis. The designers and users of these order sets should be approached to build consensus on using the redesigned, standardized, protocol-driven VTE prophylaxis orders, with the intent to strip out all non-standardized VTE prevention orders, and replace them with the new, standardized version.
Modular versus stand alone orders
If the order set is constructed properly, it can often be designed as a VTE prevention “module,” making it easier to integrate into the pre-existing order sets referenced above. This is preferable to order sets designed to stand alone, but even stand alone orders can be integrated into the flow of admissions and transfers with a little ingenuity. Clipping the VTE order set on to “History and Physical” forms or onto pre-existing order sets may increase adaption to an acceptable level, though we prefer modular order set design whenever possible.
Enhancing the power of the protocol
Skillful introduction of a good order set that reaches most patients has often yielded observed VTE prophylaxis rates of 70–85% (from baseline performance of 35–55%) in our local experience and in collaborative VTE prevention efforts. This performance boost is a great accomplishment, but such an approach alone is not sufficient. No matter how clear and concise the order set is, it will not always be used correctly. Moreover, acutely ill patients often have transient changes in the risk/benefit ratio of using anticoagulation, leading to lapses in VTE prophylaxis that persist beyond transient bleeding risk. To reach higher levels of performance under these constraints, a multifaceted approach using a variety of techniques has been effective in the literature [16, 22–25, 31–36] and in the collaborative. Educational programs alone [32, 37, 38] are not generally sufficient to bring about reliable VTE prophylaxis, but are needed to foster appropriate use of order sets and protocols. Periodic audit and feedback and computerized decision support can also be very effective [31, 39–43], particularly when there is an institutional protocol to hold up as the defining standard for adequate prophylaxis, but some of the more sophisticated tools are beyond the reach of many improvement teams.
Situational awareness and measure-vention
One method to enhance the power of the VTE prevention protocol has distinguished itself from all the others. This method, which we call “measure-vention,” involves identifying and measuring patients on potentially inadequate prophylaxis and intervening on them in real time. This strategy has proven successful in a variety of environments [22, 33]. The measure-vention technique for VTE prophylaxis most commonly follows a series of steps as described below.
The medication administration record (MAR) or an automated report (often generated by pharmacy) is presented to front line staff, identifying the VTE prophylaxis status of each patient on the ward. Advanced versions of this approach have actually classified each patient on the ward as being “green” (an order in place for therapeutic or prophylactic anticoagulation), the “yellow” (mechanical prophylaxis without pharmacologic prophylaxis), or “red” (no VTE prophylaxis orderd), see Fig. 1. Extracting this information from the MAR into a report creates a situational awareness, calling for explicit action on the part of the front line staff member.
The staff member (usually a staff nurse or charge nurse, but sometimes a pharmacist) is then called upon to intervene on patients that seem to be non-adherent to the protocol. For example, if a patient is classified as red, nursing can be authorized to place sequential compression devices on the patient—and if there are no obvious bleeding problems and any VTE risk factor is present—can place a simple templated note on the chart and text page the physician, asking them to either place the patient on pharmacologic prophylaxis or state the reason they choose not to do this. This method can quickly bolster VTE prophylaxis rates to 95% , and fatigue from alerts can be minimized if the intervention part of the strategy is deployed after the order set is launched. The medical staff leadership and administration need to make sure the front line staff are comfortable carrying out this strategy, and make it clear that “shooting the messenger” is unacceptable.
Measure-vention as described above provides the means to establish reliable, easy to understand metrics for VTE prophylaxis. The percent of patients on anticoagulation based prophylaxis, and the percent of patients on any prophylaxis, while not perfect metrics, are easy to assess and relatively easy to automate. These measures are actionable on the front line, yet are suitable for tracking, trending, and creating roll-up reports that could be reported to key medical staff committees and governing boards.