Key Metric # 2

Performance Tracking (selecting and reporting metrics)

Key metric # 2: incidence of hospital-acquired VTE

Ultimately what the team cares most about is how well the steps of care delivery come together to prevent hospital-acquired VTE, the main clinical endpoint, or outcome. Clearly, the incidence of hospital-acquired VTE must be one of the team’s key metrics.

A common definition for “hospital-acquired DVT or PE” would be a clot first discovered during the course of hospitalization, or discovered within 30 days of a prior hospitalization. There are various methods for trying to capture this metric in a useful way, each with its own advantages in terms of accuracy and efficiency.

Methods for Defining Hospital-Acquired VTE

*Then divide by 2 to estimate the fraction that is hospital-acquired. The literature suggests that approximately half of all cases of DVT and PE diagnosed in the hospital are hospital-acquired. Alternately, use all VTE codes listed as a secondary diagnosis as a surrogate for hospital-acquired VTE.

The first method is very simple and can be done with no effort. View the diagnosis codes for DVT and PE.

The “Better yet” option introduces the concept that the team can actually get more from a chart review than just a classification of “hospital-acquired” versus “community- acquired.” The VTE can now also be classified as “hospital-acquired while on appropriate prophylaxis” versus “hospital-acquired while not on appropriate prophylaxis.” With this method the team can plot the incidence of “preventable HA-VTE,” a subset of all HA-VTE events that communicates the most about the entire VTE prevention effort. This option would also allow surveillance for other factors that led to the formation of a hospital-acquired clot. For example, was the patient sedated or restrained? Did the patient have a central line associated clot, and if so, was the line really needed at the time the clot formed? Given the time and resources, the team could do a mini-root cause analysis to generate other potential strategies to prevent hospital-acquired VTE.

The “Best” option has all of the advantages listed above, but with the additional advantages that chart review is much easier when the patient is still in the hospital. The chart review can also be more efficient with the capability to query a digital imaging system to screen all pertinent imaging studies on a regular basis. In the 350 bed facility at UCSD a nurse or nurse practitioner screens all pertinent studies from the prior day, identifies all new hospital-acquired clots, and completes a thorough chart review on all new hospital-acquired VTE. The whole process takes less than an hour on each weekday. It can be done very efficiently by using automated search criteria if the radiology department uses a suitable digital imaging system. The team should try to create a flow of data that pulls up all pertinent diagnostic studies, complete with their reports, at the click of a button.

Depending on the limitations of the radiology information system, the team may come up with another method that is more useful and expedient.

Once the team has defined “hospital-acquired VTE” and figured out how to find the cases, it has another decision. Simply track the raw number of hospital-acquired VTE, or control for the number of patients or patient-days? Controlling for patient days at risk for VTE does add a little more work, but would reduce some of the “noise” in the data by controlling for the probability that more hospital-acquired VTE occur with higher hospital occupancy. At UCSD, for example, each month we calculate the total number of patient days for adult inpatients in the hospital > 48 hours and use that as the denominator. We use the total number of hospital-acquired VTE events as the numerator. This helped us generate a specific aim, outlined in the next section. 
Another option to consider if the team has the capacity to look at all newly diagnosed events of DVT and PE in the medical center: tracking the number of days between hospital-acquired VTE events or potentially preventable hospital-acquired VTE events, allows the team to plot “days between events.” Each event becomes a point on the x-axis, while the number between events appears on the y-axis. 

Now it is time for the team to decide, given the resources at the hospital, how to measure the incidence of hospital-acquired VTE.