SEATTLE—Stroke patients who arrive at the hospital earlier wait longer to receive IV t-PA, according to findings presented by Aaron Izenberg, MD, at the 61st Annual Meeting of the American Academy of Neurology. “On average, patients were treated 14 minutes later for every 30 minutes earlier they arrived at the hospital,” he reported.
Reexamining the Association Between Time of Arrival and Time of Treatment
“We thought it was important, especially as the treatment window is extending to 4.5 hours, to reexamine the relationship between time of arrival and time of treatment in a large cohort of consecutive stroke patients,” explained Dr. Izenberg, a neurology resident in the Department of Medicine at the University of Toronto. Data on t-PA–treated patients presenting to 13 centers in Ontario and Halifax between 2003 and 2008 were extracted from the Registry of the Canadian Stroke Network.
Two analyses were conducted—a linear regression model to examine the relationship between onset-to-arrival and door-to-needle times and a multiple regression model to assess for other potential contributing variables, such as stroke severity and gender.
A total of 5,972 patients arrived at the emergency department within four hours of stroke onset—1,564 were treated with IV t-PA, and of these, 1,411 met study criteria. The mean age of subjects was 72.3, 51.3% were male, and the average NIH Stroke Scale score was 13. The median onset-to-arrival time was one hour, and the median door-to-needle time was 1.3 hours.
Findings From Linear and Multiple Regression Analyses
In the linear regression model, door-to-needle time was inversely related to onset-to-arrival time, reported Dr. Izenberg. People who arrived at the hospital earlier waited longer to be treated, and people who arrived later tended to be treated faster. Median door-to-needle times were 1.3 hours for patients arriving within one hour of stroke onset, 1.2 hours for patients arriving within one to two hours, and 0.9 hours for those arriving within two to three hours.
In the multiple regression model, which factored in a number of variables, such as age, gender, stroke severity, and premorbid conditions, later arrival to the hospital was associated with shorter door-to-needle times, whereas lower stroke severity and onset upon awakening were associated with longer treatment times.
Why Does This Treatment Delay Exist?
“Despite our awareness that thrombolysis must be delivered as quickly as possible, on some level, physicians may still ultimately be focused on the overall treatment window of three hours (now 4.5 hours), rather than on a 60-minute door-to-needle target,” said Dr. Izenberg. He attributed this paradox to Parkinson’s Law, which asserts that work expands to fill the time available.
Another reason for delayed t-PA therapy could be that physicians might be waiting for patients to improve. “So patients who are arriving earlier might be, in some sense, given an opportunity to improve spontaneously,” Dr. Izenberg stated.
“Despite the known benefits of t-PA, physicians may hesitate to treat patients for fear of an adverse outcome, such as intracranial hemorrhage,” he added.
“Treating physicians must resist this tendency to delay thrombolysis for early arriving patients, especially as the treatment window extends beyond three hours,” concluded Dr. Izenberg and colleagues. The study was funded by the Canadian Stroke Network and conducted at the Institute for Clinical Evaluative Sciences.
—Karen L. Spittler