Does functional outcome in acute ischaemic stroke patients correlate with the amount of free-radical scavenger treatment? A retrospective study of edaravone therapy.

BACKGROUND: Edaravone is a free-radical scavenger that has been widely used for acute ischaemic stroke in Japan. However, the optimal total dosage of edaravone has not been established.

OBJECTIVE: To clarify the relationship between the gain in functional recovery (rehabilitation gain) and the total amount of edaravone used for acute-phase therapy for cerebral infarction at a convalescent rehabilitation hospital. We also sought to determine if there were differences in outcome between stroke subtypes.

METHODS: Medical records were retrospectively surveyed to identify patients who had received edaravone treatment for acute-phase cerebral infarction at Kawakita General Hospital, Tokyo, Japan, followed by recovery rehabilitation at Kawakita Rehabilitation Hospital, Tokyo, Japan, for > or = 30 days. Edaravone was initiated within 24 hours of stroke onset, and was administered as a 30 mg (1 ampoule) continuous intravenous infusion twice daily for up to 14 days. Patients were stratified into tertiles based on the total amount of edaravone used (measured in ampoules) during the acute phase (i.e. administration duration). Rehabilitation gain was defined as the change (increase) from convalescent rehabilitation hospital admission to discharge in the Functional Independence Measure-Motor (DeltaFIM-M) or Barthel Index (DeltaBI) score.

RESULTS: Of the 72 enrolled patients, 21 belonged to the lower (short-term) tertile (0-14 ampoules), 27 to the middle (medium-term) tertile (15-23 ampoules) and 24 to the upper (long-term) tertile (24-33 ampoules) groups. There was no correlation between the total amount of edaravone used and the length of stay at an acute-phase hospital. However, a significant correlation was seen between the total amount of edaravone used and DeltaFIM-M (adjusted regression coefficient 0.81; p = 0.003) and DeltaBI (0.88; p = 0.005) score in patients with cardioembolic stroke; no significant correlation was seen in other stroke subtypes. Cardioembolic stroke patients also showed improvements in both FIM-M and BI score as the total amount of edaravone used increased. The difference between the short- and long-term group was 10.1 (95% CI 2.3, 17.8) for DeltaFIM-M score, and 12.0 (95% CI 2.8, 21.2) for DeltaBI score. Patients with atherothrombotic stroke showed a similar tendency with respect to DeltaBI score.

CONCLUSION: Edaravone dose-dependently increases rehabilitation gain according to DeltaFIM-M and DeltaBI scores in patients with cardioembolic stroke, and a similar trend was also observed with respect to DeltaBI score in patients with atherothrombotic stroke. This suggests that the total amount of edaravone used is associated with its efficacy for rehabilitation gain.