Performance Measurement Network

Question: Last Known Well Version 5.2

This is follow up to a prior question: "Time Last Known Well";.

I am seeking further clarification regarding this bullet in notes for abstraction for the element "Last Known Well"

Select “No” if there is ANY physician/APN/PA documentation that Last Known Well is “UNKNOWN.” Documentation must explicitly state that the Last Known Well is unknown/uncertain/unclear. Documentation that time of symptom onset is unknown/uncertain/unclear is also acceptable when Time Last Known Well is not documented. If Last Known Well is not explicitly documented as unknown, do not make inferences (e.g. do not assume that patient woke with stroke so Last Known Well unknown unless explicitly documented.

If no one mentions a LKW at all (either Last Know Well, Time last known well, or date last known well E.g., stroke was not suspected on admission but was found later in the admission or stroke was suspected but physicians completely neglected to address the LKW in their documentation. may we enter "No" for LAST KNOWN WELL as the Time Last Known well is not documented as described in the above notes for abstraction. In this scenario the patient would fall out of the STK 4 measure rather than fail it.


The word "unknown"(uncertain/unclear) must be documented by the MD/APN/PA to exclude the case at the "Last Known Well" decision point in the algorithm (explicitly documented). There should be no inferences made about when last known well is unknown. The intent of this data element is to allow for exclusion when the physician/stroke team evaluates the patient for thrombolytic therapy and in their best medical judgement does not think that it should be given because they are unable to determine the time when the patient was last known to be well or at baseline state of health. This is the only purpose for including the data element "Last Known Well" in the measure logic. Without the data element "Last Known Well", "Time Last Known Well" would be "UTD" (case fails) when last known well is documented as "unknown" because there is no documented time.

The most common reason for exclusion from STK-4 is that the patient arrives too late to ED for t-PA. When > 2 hours, the case is automatically excluded based on the Arrival Date and Arrival Time MINUS the Date LKW and Time LKW (Timing I calculation in the algorithm). If the case makes it through (< 2 hours), there is still another opportunity to exclude it, if there is a documented "Reason for Not Initiating IV Thrombolytic". Additionally, there is a pass for delay in administration (3 to 4.5 hours) when there is a documented "Reason for Extending the Initiation of IV Thrombolytic". There is no need to overuse "Last Known Well" for purposes other than that explained above. Some cases should fail this measure. That's an opportunity for improvement.

Thank you for your inquiry.


Question Details
Focus area(s): Chart Abstracted Measure Specifications – Clinical
Related documents: STK-4,

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