Stroke Severity Improvement in Acute Period of Interfacility Transfer

In a group of individuals transferred to stroke referral centers, an early improvement of more than 4 points on the NIH Stroke Scale (NIHSS) score, despite the administration of thrombolytics, and improvements sufficient to pass the eligibility threshold for thrombectomy were found. This according to a study recently published in Neurology: Clinical Practice.

The primary outcome of this study was stroke severity, measured with the NIHSS score. Investigators performed a retrospective analysis of prospective data from individuals with acute ischemic stroke transferred to a comprehensive stroke center (CSC) from 2010 to 2016 (n=515), of whom changes in NIHSS scores were calculated. The same team of neurologists calculated the NIHSS score at the referring center and the CSC. Individuals without computed tomography (CT) images from the referring hospitals and CT angiography from the CSC (n=9) and individuals without an NHSS score at the referring hospital and receiving CSC (n=1) were excluded. Early rapid improvement (ERI) was defined as a change in the NIHSS score ≥4 points during the interfacility transfer. Logistic regression was used to identify factors associated with ERI and to control for patient characteristics available on arrival.

From the sample of 505 individuals, the median age was 71 years, 42% were women, and 90.7% could ambulate independently. At the initial transfer, the median NIHSS score was 11 (interquartile range [IQR] 5-18), and when arriving at the CSC, it was 9 (IQR 3-17), with a median change of 0 (-3 to 0). Four point changes were seen in 74.5% scores (7% increased ≥4 points, and 19% decreased to ≥4). In 85% of cases, change in NIHSS score did not cross the threshold for thrombectomy. In multivariable modeling, ERI was associated with individuals able to ambulate before the index stroke (odds ratio [OR] 5.79, P =.02) and higher initial NIHSS (OR 1.06 per point, P =.001). In this sample, based on the NIHSS score, 40% of individuals transferred to the CSC were ineligible for thrombectomy.

Among the study limitations, the investigators acknowledge that some biases could have been introduced when excluding individuals without CT angiography and NIHSS scores. Lack of information regarding the timing of the symptomatic intracranial hemorrhage relative to the time of NIHSS measurement, lack of information regarding the number of individuals that developed seizure between measurements, and bias introduced by the same neurology team could have served as limitations. Lastly, the population in this study comes from an academic medical center, which could limit the generalizability of findings.

The researchers of the study concluded that with improvements in NIHSS score, some individuals could demonstrate symptoms resolution that would forgo the need of thrombectomy under current guidelines, as seen by the lack of interaction between the team in charge of thrombolysis administration in the CSC. This data may be useful for resource planning, triage, and intervention planning, including preparing a thrombectomy team at receiving hospitals.

Reference

Zachrison KS, Leslie-Mazwi TM, Boulouis G, et al. Frequency of early rapid improvement in stroke severity during interfacility transfer [published online May 8, 2019]. Neurol Clin Pract. doi: 10.1212/CPJ.0000000000000667