Background: We aimed to identify relative SBP reduction thresholds associated with the most favorable functional outcome after ICH.
Methods: We performed an individual participant data meta-analysis of 5 randomized trials (INTERACT1-4 and ATACH-II). The relative reduction measurements in SBP were defined as the percentage decrease (a) from baseline SBP to the lowest SBP in 1-hour (primary) and (b) from baseline SBP to the achieved mean of SBP between 1-24 hours. Associations with functional outcome, assessed as an unfavorable shift in scores on the 90-day mRS were examined in multivariable logistic regression models and tested for non-linearly using restricted cubic splines. Heterogeneity of associations between the 1-hour relative SBP reduction and functional outcome by age, sex, history of hypertension and diabetes and baseline SBP were further explored.
Results: Among 11,283 participants (mean age, 62.6 years; 36.0% female; mean baseline SBP, 176.9 mmHg), the association between 1-hour relative SBP reduction and unfavorable functional outcome was U-shaped with an inflection nadir at around 20%. Associations differed by sex, baseline SBP, and history of diabetes (all p for interaction <0.05). Similar U-shaped associationwas also observed in relation to the achieved level in 1-24 hours, with greatest apparent benefit at approximately 30%.
Conclusions: In acute ICH, a first‑hour relative SBP reduction of around 20% and a 24‑hour reduction target of 30%, individualized to the presenting SBP, were associated with the most favorable functional outcome. Larger reductions may attenuate the benefit and should be applied cautiously, particularly in patients with very high baseline SBP.