Thank you for your question. The intent of the Baseline State/Last Known Well data element (2.16.840.1.113883.3.117.1.7.1.417) is to identify patients' baseline state of health, i.e. when the patient was last known to be without the signs and symptoms of the current stroke. The Time of Symptom Onset data element (2.16.840.1.113762.1.4.1045.14) is used to identify the onset of stroke symptoms. In the denominator, the measure looks to identify the relationship between the Baseline State or Symptom onset and the encounter. In the numerator, the data elements are used to identify the relationship between the administration of t-PA and the time of either Baseline State or Symptom Onset. In both cases, the eCQM uses “Baseline State” and “Time of Symptom Onset” interchangeably. We are considering the “baseline state” the same as “last known well.” Please let us know if this response does not answer your question.

Based on the updated eCQM specification and logic for measure NQF number 0437 for Thrombolytic Therapy, the denominator and numerator definition for "Baseline State/Last Known well" and "Time of Symptom Onset" seem to be the same. The two can be very different. For example, please consider the following: Patient is completely well and goes to bed on 1/1/15, three days later patient has symptoms of stroke on 1/4/15. The “Last Known well”/“Baseline State” would be 1/1/15 and the “Time of Symptom Onset” would be 1/4/15. Please clarify the difference between "Baseline State/Last Known Well" and "Time of Symptom Onset" for denominator and numerator with consideration to the updated eCQM specs for the STK-4 measure NQF-0437? Also are you considering the "baseline state" as the same as "last known well" for this measure? Thank you