Introduction: Laboratory turnaround times have historically delayed the management of acute stroke (i.e, last known normal </=24 hours) in time-sensitive situations. Although a coagulation profile is not routinely required before administering thrombolysis, it is necessary if there is a suspicion of coagulopathy or if the available patient information is inadequate. Point-of-care devices such as i-STAT provide an alternative, rapid means of obtaining INR in stroke patients. It could be instrumental at a free-standing emergency department or other sites lacking a core laboratory. Centers for Medicare and Medicaid Services and the College of American Pathologists established the total allowable error for acceptable performance to be ± 15%. Objective: This study aims to determine the agreement between i-STAT and the standard laboratory-based system, Stago, for measuring INR in stroke patients. Methods: We collected INR from fifty acute stroke patients presenting to the Emergency Department of Houston Methodist Hospital from 14 April 2025 to 17 June 2025, using both i-STAT and laboratory testing, along with the mean and median turnaround times. R V4.5.0 was used to run the Bland-Altman analysis to identify the mean difference between the two methods, and the upper and lower limits of agreement (LoA). Pearson correlation analysis was also performed to identify the linear association. Results: The mean and median turnaround times of i-STAT were 28 and 26 minutes, respectively, compared to 50 minutes and 48 minutes for the lab results. Bland-Altman analysis revealed a mean difference in INR values of 0.03, indicating minimal systematic bias. The upper LoA was 0.29, while the lower LoA was -0.24. Hence, the two methods show an acceptable level of agreement between them. Pearson’s coefficient of 0.63 (p-value <0.001) demonstrated a strong positive correlation between the two methods. Conclusion: i-STAT INR values are comparable to the laboratory values. Given the consensus regarding INR before thrombolytic administration applies to a relatively smaller population of patients presenting within 4.5 hours, including those on warfarin or unsure about anti-coagulation usage, i-STAT is a reasonable alternative. It will aid timely decision-making and reduce healthcare disparities at sites lacking a core lab facility, while maintaining the quality of care provided. Further projects are required to determine an i-STAT cut-off value for clinical application in the stroke population.
Asmar et al. (Thu,) studied this question.