Despite strong recommendations from guidelines and regulatory agencies, national rates of intravenous thrombolysis for ischemic stroke continue to be quite low overall. However, tPA administration appears to have increased from previous years and particularly increased in years after the Joint Commission began to accredit institutions as “Primary Stroke Centers”.11
The oldest patients and African Americans were less likely to receive thrombolytics, while patients with atrial fibrillation were more likely to receive thrombolysis, potentially related to atrial fibrillation causing more severe strokes.15
A total of 5.4% of patients who received tPA were diagnosed with intracranial hemorrhage, and the inpatient mortality rate of patients with tPA was 9.0%.
The exact optimal rate of thrombolysis administration for the patients in our study is unknown, as the NHDS database lacked detailed information on factors that would preclude tPA administration such as late timing of presentation and mild stroke symptoms.3
Studies conducted in stroke registries and regional settings have found that only approximately 15% to 32% of patients presenting with ischemic stroke arrive within 3 hours of symptom onset, and of these, only about 40% to 50% are eligible for tPA clinically.9,10,16–19
However, even among presumed eligible patients, tPA administration rates only range between 25% and 43%,17,19,20
and the ideal rate is likely to be higher than the very low rates we observed in our study. Newer evidence that extending the time window where tPA may be given safely may increase the number of eligible patients.21
Patients who received thrombolysis had higher mortality rates than patients who did not. Although we were unable to determine a causal association, prior observational studies of tPA administration for acute stroke have found that patients with more severe neurologic deficits were more likely to receive thrombolysis.17,18
The 9.0% inpatient case-fatality rate observed in our study compares favorably to the 13.4% mortality rate after tPA reported in a post-approval meta-analysis of safety outcomes22
and the rate of intracranial hemorrhage in our analysis was similar to those observed in other settings.9,22–25
We were unable to determine whether intracranial hemorrhages in our study were as a result of tPA administration or whether patients who received tPA were more likely to have intracranial hemorrhages detected, such as may be due to increased frequency of head imaging.
Larger hospitals were more likely to administer tPA. This may reflect regionalization of stroke care, particularly in those designated as stroke “centers of excellence.” As well, there is some evidence that there is a “learning curve” with thrombolysis administration, where guideline-recommended practice and use of tPA increases with additional experience with the drug.9,26
Promoting systems that allow for rapid triage and diagnosis of acute stroke should be encouraged and hospital leaders should develop strategies that allow for early recognition of potential tPA candidates.
There are several limitations to our analysis. The NHDS does not collect detailed data on clinical or presenting features of stroke, and so we lacked information on stroke severity and eligibility for administration of thrombolysis. Our study may have underestimated the overall rates of thrombolysis, as it was dependent on diagnostic codes. A previous study of 34 patients who received tPA found that although the 99.10 code was 100% specific, the code identified only 17 patients who actually received tPA (sensitivity of 50%).20
Another study comparing Medicare administrative claims data to actual pharmacy billing charges for tPA found that administrative data underestimated the rate of tPA administration by approximately 25% to 30%.12
If a diagnostic code sensitivity of 50% was assumed, rates of tPA administration in our study may have been as high as 4.8% (95% CI, 4.1–5.5%) by year 2006.