An updated systematic review and meta-analysis investigating perihematomal edema and clinical outcome after intracerebral hemorrhage

The relationship between perihematomal edema (PHE) and intracerebral hemorrhage (ICH) outcomes is uncertain. Given newly published studies, we updated a previous systematic review and meta-analysis assessing the prognostic impact of PHE on ICH outcomes.Databases were searched through September 2022 using pre-defined keywords. Included studies used regression to examine the association between PHE and functional outcome (assessed by modified Rankin Scale [mRS]) and mortality. The study quality was assessed using the Newcastle-Ottawa Scale. The overall pooled effect, and secondary analyses exploring different subgroups were obtained by entering the log transformed odds ratios and their confidence intervals into a DerSimonian-Laird random effects meta-analysis.Twenty-eight studies (n=8655) were included. The pooled effect size for overall outcome (mRS and mortality) was 1.05 (95% CI 1.03, 1.07; p<0.00). In secondary analyses, PHE volume and growth effect sizes were 1.03 (CI 1.01, 1.05) and 1.12 (CI 1.06, 1.19), respectively. Results of subgroup analyses assessing absolute PHE volume and growth at different time points were: baseline volume 1.02 (CI 0.98, 1.06), 72-hour volume 1.07 (CI 0.99, 1.16), growth at 24 hours 1.30 (CI 0.96, 1.74) and growth at 72 hours 1.10 (CI 1.04, 1.17). Heterogeneity across studies was substantial.This meta-analysis indicates that PHE growth, especially within the first 24 hours after ictus, has a stronger impact on functional outcome and mortality than PHE volume. Definitive conclusions are limited by the large variability of PHE measures, heterogeneity, and different evaluation time points between studies.