Bridging Continents, Closing Gaps: A Multicenter Cohort Study on Subarachnoid Hemorrhage Outcomes and Health Care Disparities.

[BACKGROUND] Low sociodemographic index (SDI) countries bear a disproportionate burden of aneurysmal subarachnoid hemorrhage (SAH) yet remain underrepresented in medical research.

[METHODS] A retrospective multicenter cohort of 1145 patients from tertiary centers in Brazil and the USA (2012-2024). Demographics, clinical severity (WFNS, modified Fisher scale, mFs), treatment modality, and outcomes were compared. Primary outcomes were in-hospital mortality and poor functional outcome (mRS > 2); secondary outcome was hospital length of stay (LOS). Multiple imputation was used for missing at random (MAR)-type missingness; adjusted models incorporated Bonferroni correction.

[RESULTS] Mean age was 54.5 ± 14.4 years; 73.9% female. Racial/ethnic distribution was 49.6% White, 23.5% Black, 19.5% multiracial, 1.7% Asian, 5.6% other, and 0.2% Native American. Hypertension and smoking were more prevalent among American patients, Black and White individuals, respectively. Brazilian patients underwent microsurgery more often (61.9% vs. 92% endovascular in the USA) and had markedly longer time to treatment (77.7 vs. 4.3 h; p < 0.0001). In-hospital mortality was higher in Brazil (23.4% vs. 13.4%; OR 1.98; p < 0.0001) and remained significant after adjustment. LOS was shorter in the USA (-5.4 days; p = 0.0021). Black Brazilians had worse outcomes (OR 2.3; p = 0.0028), while White patients trended toward lower mortality overall (OR 0.7; p = 0.0350). Rehabilitation access differed sharply (39.8% vs. 0.8%). Poor long-term outcome was more common in Brazil (53.2% vs. 38.8%; p < 0.0001).

[CONCLUSIONS] Although USA patients had more vascular comorbidities, Brazilian hospitals experienced substantially higher mortality and long-term disability. These differences were consistent with disparities in care delivery and resource availability-reflected by longer treatment delays, differing treatment modalities, and limited access to post-acute rehabilitation-beyond measured patient-level risk, while also underscoring the importance of primary care-based prevention in high-income settings.