Cortical superficial siderosis and bleeding risk in cerebral amyloid angiopathy: A meta-analysis.

Objective: To assess the association of cortical superficial siderosis (cSS) presence and extent with future bleeding risk in cerebral amyloid angiopathy (CAA).

Methods: This was a meta-analysis of clinical cohorts of symptomatic patients with CAA who had T2*-MRI at baseline and clinical follow-up for future intracerebral hemorrhage (ICH). We pooled data in a 2-stage meta-analysis using random effects models. Covariate-adjusted hazard ratios (adjHR) from multivariable Cox proportional hazard models were used.

Results: We included data from 6 eligible studies (n = 1,239). cSS pooled prevalence was 34% (95% confidence interval [CI] 26%-41%; 87.94%; < 0.001): focal cSS prevalence was 14% (95% CI 12%-16%; 6.75%; = 0.37), and disseminated cSS prevalence was 20% (95% CI 13%-26%; 90.39%; < 0.001). During a mean follow-up of 3.1 years (range 1-4 years), 162/1,239 patients experienced a symptomatic ICH-pooled incidence rate 6.9% per year (95% CI 3.9%-9.8% per year; 83%; < 0.001). ICH incidence rates per year according to cSS status were 3.9% (95% CI 1.7%-6.1%; 70%; = 0.018) for patients without cSS, 11.1% (95% CI 7%-15.2%; 56.8%; = 0.074) for cSS presence, 9.1% (95% CI 5.5%-12.8%; 0%; = 0.994) for focal cSS, and 12.5% (95% CI 5.3%-19.7%; 73.2%; = 0.011) for disseminated cSS. In adjusted pooled analysis, any cSS presence was independently associated with increased future ICH risk (adjHR 2.14; 95% CI 1.19-3.85; < 0.0001). Focal cSS was linked with ICH risk (adjHR 2.11; 95% CI 1.31-2.41; = 0.002), while disseminated cSS conferred the strongest bleeding risk (adjHR 4.28; 95% CI 2.91-6.30; < 0.0001).

Conclusion: In patients with CAA, cSS presence and extent are the most important MRI prognostic risk factors for future ICH, likely useful in treatment planning.

Classification Of Evidence: This study provides Class III evidence that in symptomatic CAA survivors with baseline T2*-MRI, cSS (particularly if disseminated, i.e., affecting >3 sulci) increases the risk of future ICH.